Crusader 270 electronic ignition conversion issues

[junior4597]

I was wondering if I could get some advice on an issue I am having. I have twin 270 Crusaders with the old point set-up. I recently experienced some bogging down on the port engine and consistently had to adjust its points so I decided to convert them to electronic. I purchased the Pertronix Igniter II model along with a new .6 ohm coil. The installation was simple, for the most part. I did have a Ballast Resistor that I took out of the equation - per the recommended directions. Once I completed the installation and started the engines they ran a little rough so I assumed the next step was to adjust the timing. This was a challenge because the harmonic balancer didn't have any numbers on it, just the indicator. So, being a novice I adjusted the distributor until it "sounded" and idled smoothly. I then set the rpm on both idles to match up. At idle it purred so I thought it was accurate and decided to take her out and open it up a bit. I was disappointed. Typically at 3000 rpm I'm doing about 21 MPH - in this case I was doing 14 MPH and it felt sluggish as if the horsepower had been diminished. The tacks were in balance and she fired up right away but under load it was certainly not living up to normal horsepower. To make it even worse I occasionally heard a loud bang, I thought I hit something. The bang happened without reason and happened about 5-6 times so I lowered the rpm's and took her back in. I thought maybe the bang was an arc? A really loud one? I'm still puzzled by it and am worried I did something wrong. I guess, 1 - does anyone have any experience with converting to the electronic ignition? 2 - is the installation as easy as they make it sound? 3 - does timing really need to be done as part of the conversion? 4 - if it does how do I time it correctly without any degree markings on the HB? and 5 - what about that bang?? could it have been an arc? I'm concerned. Any help would be greatly appreciated. Sorry this was so long...........

 

[makomark]

timing needs to be reset after the conversion...that said, the first thing you SHOULD have done was verify the distributor was functioning correctly - specifically, its advance function.

As far as setting the base timing, you can use the flywheel marks...a better solution is to buy a pair of timing tapes and use them instead. More accurate and will also let you verify the timing advance curve - which, BTW, is were I'd guess your "lost power" is hidden.
Only trick is to reverse the installation of the tape on the RH engine.

Bang - could have been a lean pop due to inadequate timing function...if you didn't have it before the conversion, it is highly likely to be coupled to the timing.

There have been a slew of postings on ignition timing on this board - use the search function to find them.

 

[junior4597]

Thanks for the info. I did find some great info on this subject up here as you stated. I think I understand what needs to be done but seeing this is my first attempt at timing an ignition I have a few points I need clarified.

a few facts:
Engines are 1987 Crusaders model 207
There is no Vacuum Advance so I don't need to "remove" it to adjust timing
Horse power was fine before electronic ignition conversion - meaning the distributors were fine and timed before the conversion
7 inch diameter harmonic Balancer (HB)

My next steps to complete are - Just need verification this is accurate (I'm sure I'm off)

1. Warm up engine to operating temp - 150 degrees

2. Do I need to adjust cylinder 1 to top dead center? I heard to manually move the harmonic balancer by hand with your finger in the spark plug hole till it hits on the compression stroke. Is that possible with the engine at 150 degrees?? Need clarification on that one - if it in fact needs to be done at all.

3. I did buy some timing tape - the STB engine rotates clockwise when looking at the harmonic balancer, the port engine rotates counter clockwise when looking at the HB. Am I to apply the tape so that zero on the tape lines up with the groove on the HB? I believe so. And if so how is that oriented? Meaning for example on the STB engine if I apply the tape on the groove at zero and with the numbers counting up in advance to the tight of the mark and counting to 10 in "retard" to the left of the mark. As the HB rotates clockwise this will mean the high end of the advance side of the mark will hit the gauge first. Is that accurate or is that backward and the tape needs to be flopped upside down? And then of course whatever that is I do the opposite for the port engine. Not sure if that made sense in how I explained it.

4. Set the advance to 10 with the timing light at idle (adjust distributor accordingly)- both engines

5. Rev the engine to 3000 RPM and ensure the advance is between 32-38 (adjust accordingly) - I'm reading that this setting is more important than the 10 degrees at idle - true? If so and it needs to be adjusted at 3000 RPM doesn't that change the original setting at 10 when on idle. I'm confused at that one.

6. Adjust idle screw on the carb accordingly so idle is around 800 RPM.

This is what I was able to gather from all the posts I read. I guess if anyone can add/subtract my steps to follow I'd greatly appreciate it. Remember this is my first attempt but it does seem basic - just have to get the first one under my belt!

Much appreciated!

 

[makomark]

your steps are ok - #1 is optional as is #2.

The way you typed #3 it is ambiguous between the two engines. The convention with marine engines is to describe their rotation as LH or RH when looking at the flywheel. As far as applying the tape, clean the balancer first. The 0 does align with the groove. you want to apply the tape so that the numbers "go under" the pointer and "count down" as the balancer rotates, if that makes sense. Your description is ok, I jst added mine to give you another way of looking at it. As yes - apply the tape backwards for the other engine as long as it rotates the opposite way.

#4 ok

#5 - you may have to go to 3400 or even 3600 to get the full advance in the distributor...32 would be an upper bound unless you know better - I sure would NOT run it up to 38 degrees. if the timing doesn't advance, you need to check the weights and springs inside the distributor.

#6 - I set the idle rpm with the engines fully warmed up and in gear...800 is a little high but ok. Big thing is to make sure they are under 1000 when idling out of gear once warmed up.

I would ensure the advance function works before dialing in the final timing. The total advance is much more important than the inital value

 

[junior4597]

Great! I think I got it. One last question. I start off at 10 degrees BTDC at idle. I also understand that my total advance is the most important and it seems the numbers for that model engine is around 32 degress in advance - I'll stick with that number. So, if it's starting at 10 degrees at idle and i ramp up to say 3400-3600 RPM (as you state) will I see the advance number at 32 or 22? Meaing my ultimate number is 32 degress at 34k-36k RPM so am I seeing 22 on the tape and adding the initial 10 to get my 32 and locking it down there or am I looking for 32 degrees on the tape at that RMP. Just want to ensure I dont go over or under by the 10 degrees.

making sense now, almost there....

Thanks!

 

[RicardoMarine]

1 - does anyone have any experience with converting to the electronic ignition?
2 - is the installation as easy as they make it sound?
3 - does timing really need to be done as part of the conversion?
4 - if it does how do I time it correctly without any degree markings on the HB? and
5 - what about that bang?? could it have been an arc?

1 - Yes, and when I convert, it involves a completely new ignition distributor! NO Pertronix conversion kits for this kid.
The kits used Pertronix's version of Hall Effect.
They do ZERO to correct any advance malfunction, and ZERO for any wear that may have occured to our distributors, of which are generally getting old by the time these coversion kits are considered.


2 - Yes, they are fairly easy to install.
The pick up sensor is sensitive to a correct alignment with the magnetic unit, and sometimes this needs to be addressed.


3 - After the conversion is completed..... Yes, absolutely!


4 - As Mark suggested, if the balancer diameter is known, you can purchase and apply the correct decal.
For a conventional engine orientation the decal will install:
Port engine = zero from TDC mark towards Port.
Stbd engine = zero from TDC mark towards Stbd, and will be flipped around.


5 - Can't help you on that one! I was in the cabin making myself a cocktail at the time!

My next steps to complete are - Just need verification this is accurate (I'm sure I'm off)

1. Warm up engine to operating temp - 150 degrees

2. Do I need to adjust cylinder 1 to top dead center? I heard to manually move the harmonic balancer by hand with your finger in the spark plug hole till it hits on the compression stroke. Is that possible with the engine at 150 degrees?? Need clarification on that one - if it in fact needs to be done at all.

3. I did buy some timing tape - the STB engine rotates clockwise when looking at the harmonic balancer, the port engine rotates counter clockwise when looking at the HB. Am I to apply the tape so that zero on the tape lines up with the groove on the HB? I believe so. And if so how is that oriented? Meaning for example on the STB engine if I apply the tape on the groove at zero and with the numbers counting up in advance to the tight of the mark and counting to 10 in "retard" to the left of the mark. As the HB rotates clockwise this will mean the high end of the advance side of the mark will hit the gauge first. Is that accurate or is that backward and the tape needs to be flopped upside down? And then of course whatever that is I do the opposite for the port engine. Not sure if that made sense in how I explained it.

4. Set the advance to 10 with the timing light at idle (adjust distributor accordingly)- both engines

5. Rev the engine to 3000 RPM and ensure the advance is between 32-38 (adjust accordingly) - I'm reading that this setting is more important than the 10 degrees at idle - true? If so and it needs to be adjusted at 3000 RPM doesn't that change the original setting at 10 when on idle. I'm confused at that one.

6. Adjust idle screw on the carb accordingly so idle is around 800 RPM.

This is what I was able to gather from all the posts I read. I guess if anyone can add/subtract my steps to follow I'd greatly appreciate it. Remember this is my first attempt but it does seem basic - just have to get the first one under my belt!

Much appreciated!

1 I agree wtih Mark.

2. That would be a means of determining when the cylinder is coming up on the C/S. Not necessary for what you will be doing.


3. NOTE of Caution: The balancer diameter must be known at the time that you purchase the decal.

You must have a non-conventional installation... so I'll ditto Mark regarding LH or RH when looking at the flywheel.
Typically a Port engine will be STD LH Rotation...... Stbd engine will be REV RH Rotation.

That is correct..... line up the decal ZERO with the balancer TDC mark, but make darn sure that the following degrees are in favor of Engine Rotation, in that they "lead" the TDC notch in the direction of rotation.



4. If 10* is your OEM BASE advance, then yes.
You're not done yet...... so stay tuned.


5. between 32-38 * @ 3000 RPM is a huge RED Flag for me. Are you by chance consulting with automotive people???????
Please DO NOT use automotive specs or advice from strickly automotive minded mechanic types.
See your OEM ignition timing specs.

Yes.... the Progressive and Full In degrees of advance are much more important than BASE advance.
One of us probably needs to go into more detail for you regarding actually strobing your timing marks and what we're ultimately after.


6. Again, see your OEM specs. 800 RPM is a bit high for a marine engine and transmission.

This is what I was able to gather from all the posts I read. I guess if anyone can add/subtract my steps to follow I'd greatly appreciate it. Remember this is my first attempt but it does seem basic - just have to get the first one under my belt!

Even while you are on a Marine forum, and a very good forum, learn to know and trust your source.
I see automotive suggestions being posted quite often.


,

 

[RicardoMarine]

I did not see this one until after I posted.

Great! I think I got it. One last question. I start off at 10 degrees BTDC at idle. I also understand that my total advance is the most important and it seems the numbers for that model engine is around 32 degress in advance - I'll stick with that number. So, if it's starting at 10 degrees at idle and i ramp up to say 3400-3600 RPM (as you state) will I see the advance number at 32 or 22? Meaing my ultimate number is 32 degress at 34k-36k RPM so am I seeing 22 on the tape and adding the initial 10 to get my 32 and locking it down there or am I looking for 32 degrees on the tape at that RMP. Just want to ensure I dont go over or under by the 10 degrees.

Junior, once you begin strobing your new timing marks this will begin to make more sense.
Remeber..... what you see as you strobe, will always include BASE advance and then what ever progressive is occuring.

BASE is what we start out with and set initially.
BASE Does NOT include any progressive advance until the centrifugal system begins.
Once out of BASE RPM range, as you increase RPM you can't help but see the progressive advance occur.
The timing light strobe flash will cause this to appear.

When you reach an RPM where the advance discontinues, that will be your limit RPM, or Full In RPM.
The more important numbers will be at/near 3,200 RPM or so.
Again, see your OEM specs so you do not risk engine damage.

I'll suggest as an estimate only, that you're going to see approximately 26* @ 3k rpm, 28* @ 3.2k rpm, 30* @ 3.4k rpm, and perhaps maybe 32* @ 3.6k rpm if we haven't already reached Full In.
If this is a good quench built engine, the numbes may be higher.

.


.

 

[junior4597]

Thanks Rick - I think we are all in agreement on the steps and I appreciate your comments as I learn this process - it's a great help. My only issue is that I don't have and surprisingly cannot find any OEM timing specs online. I have the original Operation and Maintenance Manual for these engines but it doesn't state any base or advance settings. I have reached out to both Tiara and Crusader to see if I can obtain this info. Haven't heard back from them yet. I guess if I cant find that my next steps would be to call a Crusader certified mechanic and hope he is kind enough to shout those numbers out to me over the phone! Just so I'm exact in my calibration.

Much appreciated - this site is extremely useful/helpful and hope to "payback" when someone else is in need. Great forum!

 

[RicardoMarine]

Thanks Rick - I think we are all in agreement on the steps and I appreciate your comments as I learn this process - it's a great help.
1..... My only issue is that I don't have and surprisingly cannot find any OEM timing specs online.
2.... I have the original Operation and Maintenance Manual for these engines but it doesn't state any base or advance settings.
I have reached out to both Tiara and Crusader to see if I can obtain this info. Haven't heard back from them yet. I guess if I cant find that my next steps would be to call a Crusader certified mechanic and hope he is kind enough to shout those numbers out to me over the phone! Just so I'm exact in my calibration.

Much appreciated - this site is extremely useful/helpful and hope to "payback" when someone else is in need. Great forum!

1..... I'll post a Volvo Penta advance curve for you below, as to give you an idea of what you'll be looking for.

The engine build influences what we can use for a progressive and TA for the SBC Marine engine.
If these are original, you may want to ask Crusader about the build (piston style and combustion chamber volume).
If someone has made changes to cylinder head combustion chamber volume, and/or piston style, you'll want to know this as well.

Nut shelling this:
If a quench piston and good quench dimension was used, you can be more aggressive with both the progressive and TA.
If using the full dished pistons, you'll want to be less aggressive and more conservative (this piston cannot create a quench).

Being rather conservative will not damage an engine, but may cause less performance and a greater fuel burn.
Being more aggressive for a build that may not be suited for it....., may damage an engine.
If in doubt, always error on the side of caution.

2.... Doubt that you'll find anything useful in an Operation and Maintenance Manual for these engines.
I think that you'll need the OEM Service or Work Shop manuals in order to find this info.

******************************************

This is an example curve only since there are some unknowns.

Note that BASE advance is not shown in the vertical scale, and will need to added when doing the math.
However, BASE advance will be included when strobing your timing marks.

Also note that any change to BASE advance, is an equal change to the TA.
IOW, if TA is too great, expect a change to BASE IF the change to BASE can correct TA.

I don't know who modified this curve. I can only assume that the lighter line is original, and that the darker line represents a modified version.
Basically, this is what you'll be looking for.

 

[junior4597]

Well, even though I thought I knew what needed to be done here I still have continual issues. Per all of the recommendations I was able to determine that the OEM base timing was 10*. I used the timing stickers and applied them the only way where each HB when on rpm made an advance up the chain of numbers. I believe those were placed correctly. Set the base at 10* on each engine with the light and then increased rpm till about 3k and the advance maxed out at exactly 28* - per what people have suggested. Locked down the distribs and thought I was golden. Took her out for a spin and upon throttle at about 2k rmp she started to get sluggish and didn’t feel right. the STBD engine popped again, like a loud arc, so disgusted I turned her around and brought her home. Thought I had it as the base was 10* on each and the TA was 28*. My next step is to bring down the base to about 7* to see if that makes a difference. Otherwise I have to suck it up and call a mechanic - if I'm lucky to find one that travels! Anyone have any other thoughts? At idle she purred, it's only when under load. Maybe 10* base is too far in advance?? One thing that was difficult to figure out was that the arrow on the HB for the port engine was located on the port side of the HB when facing it. On the STBD engine it was also on the port side when facing it. That made the STBD engine difficult to time but I think I got it. You would figure the arrow would be on the STBD side of the STBD engine - maybe just easier to reach. Well, I'm at wits end so any other thoughts would be helpful. If not I'll have to break down and not accomplish this task!

Thanks

 

[makomark]

Don't throw in the towel yet....you are getting a very cheap lesson. Besides, as you describe your situation, the sooner you get all this stuff figured out, the better off you will be.

Sounds like your timing advance is in a functioning state. Assuming the rest of the secondary ignition is ok, the recurring pop could be from going lean so you need to check the fuel system. Filter(s) changed lately? Do you still have the factory canister on it, too? Easy access to a pair of outboard fuel cans or a set you can borrow?

 

[junior4597]

Yea, just a little discouraged as I thought this would have been easy. Take that with a grain of salt! So, here are a few more facts as I'm hearing similar recommendations from others, friends. None of the issues that have been presented here were occurring PRIOR to the conversion to the electronic ignition kit. All of this stuff happened after the installation. So, rotors, caps, wires, plugs, mechanical advances, coil, fuel filters, carbs, etc. etc were all in working order (noticed I left out "perfect" as who knows). I know to start small because most of the time the issue is so basic that it eludes you. That said I'm not suggesting that it couldn't be any of these things and not the timing but in all honesty I doubt it. The only thing I did was to remove the points and the coil as well as take out the ballast resistor out of the mix, that's all. I installed the Pertronix II conversion kit along with the .6 ohm 12v coil. From that point on it ran rough which meant the next step was the timing (didn't realize I actually had to re-time it as part of the conversion as a friend did the same thing and never had to time). So, I could go out and order new rotors, caps, wires etc. etc (good to have spares anyway) but I think it's all going to lead back to the timing. Based on the engine plate it says 10* for both RH and LH rotation. If I applied the stickers correctly I got them both at 10*. When they advance they max out at 28* around 3k RPM. Here is where I may be missing the curve.

If I can lay out my logic here – I set the base at 10* on idle running around 700 RPM. I accelerate the engine to 3k RPM and I see the advance max out around 28*. These are the 2 numbers I have heard over and over. Since I start at 10 and it maxes at 28 am I done?? No further adjustments? Say it maxed out at 22* (and I know it needs to be at 28*) would I advance it to get to 28*? Or when I’m at 28* on 3k RPM do I then have to retard it back 10* to get to 18* at 3k RPM (subtracting the original 10* from base). I think this is where I’m off, I don’t really understand the “curve”. I guess my main question is do I need to adjust the distrib once its 28* on 3k RPM? Or do I leave it there? If I leave it there then I really didn’t make any adjustments short of the original base at 10* - which im hearing is not the most important number. Does that make sense? I wish there was a “timing hotline”! lol.

 

[makomark]

There's a timing hotline but I doubt you want to pay the going rate.

The short answer on timing is the total advance number is the most important. the fact that your advance mechanisms work is also key. don't sweat the initial number - as long as it restarts easy when hot, it isn't too important.

I'd say you timing is done. If you don't know how old the rest of the ignition system is, you can do the tuneup, if you wanna.

did you remove any high tension wires from the cap? - verify all the wires are seated in the cap and that the boots are secure (both ends). make sure the inside of the cap is clean, too. also ensure the firing order is correct. The owner's manual has good diagrams for both engines. You could even do the plugs - just be aware that the more 'new parts' you put into each engine, the more variables you will introduce until the issue is resolved.

 

[RicardoMarine]

Are you suggesting that each harmonic balancer decal is installed in the same direction from the TDC mark???? IOW, when you strobe your timing marks, are you seeing the same advance direction at either engine????

Do you have a Std LH Rotation engine and a REV RH Rotation engine..... or do you have a reversing transmission on the Stbd side????
IOW, do you have two Standard LH Rotation engines?????

As I mentioned earlier, you really need to see your OEM ignition curve information, and if that means contacting Crusader, that's what I'd do.
28* @ 3k rpm may be OK for a quench built SBC, but may be perhaps a bit much for a non-quench build.
However, if you did detonate this under load, and for any length of time, you would have certainly sustained damage.

Detonation that has not yet caused damage, will indeed hurt performance, but we rarely escape damage if allowed to continue for any length of time. It is also rather silent compared to pre-ignition, and when in an enclosed engine bay, it can be difficult to hear audibly.

In post #12, you mention "None of the issues that have been presented here were occurring PRIOR to the conversion to the electronic ignition kit". My guess would be Pertronix kits???
The Pertronix kit, IMO, is a rather cheesy way to obtain electronic triggering. You'd need to read quite a bit on this to fully understand why I suggest this.

Good news is, your mechanical advance units appear to be working in that a BASE of 10* offered the advance of 28* that you were seeing.
Good news #2, is that both ignition distributors did the same (although that 28* needs to be further discussed, IMO).

Your friend who did not re-time his ignition after the Pertronix install, either doesn't care much, or he was very lucky.
You, on the other hand, are smart for having done so.

1.... If I applied the stickers correctly I got them both at 10*. When they advance they max out at 28* around 3k RPM. Here is where I may be missing the curve.

2.... If I can lay out my logic here – I set the base at 10* on idle running around 700 RPM. I accelerate the engine to 3k RPM and I see the advance max out around 28*. These are the 2 numbers I have heard over and over. Since I start at 10 and it maxes at 28 am I done?? No further adjustments? Say it maxed out at 22* (and I know it needs to be at 28*) would I advance it to get to 28*? Or when I’m at 28* on 3k RPM do I then have to retard it back 10* to get to 18* at 3k RPM (subtracting the original 10* from base). I think this is where I’m off, I don’t really understand the “curve”. I guess my main question is do I need to adjust the distrib once its 28* on 3k RPM? Or do I leave it there? If I leave it there then I really didn’t make any adjustments short of the original base at 10* - which im hearing is not the most important number. Does that make sense? I wish there was a “timing hotline”! lol.

We'll be your "timing hot line"! LOL


1... are you absolutely certain that the decals that you purchased are the correct decals for your balancer diameter????
If not, the degree scale will be inaccurate.

2... Your logic sounds good.
Short of actually plotting out your curve, setting your BASE of 10* that rendered a TA of 28* @ 3k rpm, sounds like you understand this.

To understand the curve, look at the advance curve that I posted earlier.
Note where the advance is at the various RPM.
Remember..... this graph is minus BASE, so when you read the scale, BASE must be added.

Let's use the dark line and assume that a BASE of 10* is correct!
NOTE: do not use this dark line curve for your engine without knowning about the build.

At idle, you'll see zero advance, however, the engine is actually seeing BASE of 10* at this point.
Now look at 1k rpm. You'll see 2* of advance. Add your BASE of 10*, and the engine is actually seeing 12*.
Now look at 2k rpm. You'll see just over 10*. Add your BASE of 10*, and the engine is actually seeing 22+*.
Now let's go to 4K rpm. You'll see that the curve has already flattened out by 3.4k rpm.
At 4k rpm, the advance is now near 22+*. Add your BASE of 10*, and the engine is actually seeing 32+*.
I've skipped some.... but you get the idea.

So, we have BASE advance (no mechanical advance yet), a progressive advance (of which in your case is mechanical), and a Full In advance (or aka TA or total advance) of which is a combined advance of both BASE and Mechanical.
(EST systems are another topic, and function somewhat differently)

Bottom line..... if the BASE advance is suitable for firing on, and idling on, and if the progressive is rather linear, and if the TA comes on no sooner than at the correct Full In RPM, you should not need to make further adjustments.
But again..... your numbers need to be verified via Crusader, IMO.

As Mark said, make sure that you do not have a lean high speed F/A mixture. That alone can cause issues.


.

 

[junior4597]

Here are some answers

Are you suggesting that each harmonic balancer decal is installed in the same direction from the TDC mark???? IOW, when you strobe your timing marks, are you seeing the same advance direction at either engine???? Port engine the sticker is upside down, STBD sticker is right side up. meaning the numbers going by the flag go from 10 (retard) to 0 to 10, 20, 30 etc. as it advances by the flag. This is correct - correct? To be honest if the tape was orientated the other way I would not be able to hit any marks as I adjust the distrib BC it's too far away.

Do you have a Std LH Rotation engine and a REV RH Rotation engine..... or do you have a reversing transmission on the Stbd side???? Standard, from looking at the flywheel the STBD engine rotates righthad and the port engine rotates left hand
IOW, do you have two Standard LH Rotation engines?????

As I mentioned earlier, you really need to see your OEM ignition curve information, and if that means contacting Crusader, that's what I'd do. I spoke to Crusader and they sent me the OEM specs and the manual - 10* BTDC and the plate on the engine also shows this. Although there are NO other numbers like curve, TA etc.

In post #12, you mention "None of the issues that have been presented here were occurring PRIOR to the conversion to the electronic ignition kit". My guess would be Pertronix kits??? I called Pertronix and they said as long as it turns over its installed correctly. Kind of a dumb answer but thats what they claim. If I installed it incorrectly it wouldnt even turn over. Take it for what it is I guess.

Good news is, your mechanical advance units appear to be working in that a BASE of 10* offered the advance of 28* that you were seeing. Then I wouldn't need to do anythign else? If so what's my issue?? grr
Good news #2, is that both ignition distributors did the same (although that 28* needs to be further discussed, IMO).

1... are you absolutely certain that the decals that you purchased are the correct decals for your balancer diameter???? Yes, I measured the diameter of the HB and it was at 7", that's the sticker I used (MDS)
If not, the degree scale will be inaccurate.

At idle, you'll see zero advance, however, the engine is actually seeing BASE of 10* at this point.
Now look at 1k rpm. You'll see 2* of advance. Add your BASE of 10*, and the engine is actually seeing 12*. You mean the tape will show 12* not 2* right? If so I do see this.
Now look at 2k rpm. You'll see just over 10*. Add your BASE of 10*, and the engine is actually seeing 22+*. I see this - if 22* is the tape you are referencing
Now let's go to 4K rpm. You'll see that the curve has already flattened out by 3.4k rpm.
At 4k rpm, the advance is now near 22+*. Add your BASE of 10*, and the engine is actually seeing 32+*.

We'll be your "timing hot line"! LOL I really appreciate this guys - you have not idea - great learning too!! I feel like a pain posting all this stuff so many times....

Don't know what to do now to be honest. I've ordered new caps, rotors and coil wires but I'm betting that's not it. I am going to lower the base from 10 to 7 to see what happens tonight. The popping sond does NOT happen when 3k RPM in neutral, only when under load. So maybe the base is too high?? I have no idea at this point. Called Crusader, called Pertronix, got you guys, ordered new parts, etc. etc. I guarrantee you it's something simple that I'm missing!

 

[RicardoMarine]

Oh, so we're using colors, now eh? That works for me!

Here are some answers

Are you suggesting that each harmonic balancer decal is installed in the same direction from the TDC mark???? IOW, when you strobe your timing marks, are you seeing the same advance direction at either engine???? Port engine the sticker is upside down, STBD sticker is right side up. meaning the numbers going by the flag go from 10 (retard) to 0 to 10, 20, 30 etc. as it advances by the flag. This is correct - correct? To be honest if the tape was orientated the other way I would not be able to hit any marks as I adjust the distrib BC it's too far away.
OK, so we do have a RH and LH engine then.
But I'm questioning why the Stbd engine decal would be the one that is upside down. Typically, Stbd engines are REV RH Rotation, meaning that this decal would provide additional degrees from the balancer TDC mark towards Stbd side.
Can you explain this for us/me?

See my ** comment below.


Do you have a Std LH Rotation engine and a REV RH Rotation engine..... or do you have a reversing transmission on the Stbd side???? Standard, from looking at the flywheel the STBD engine rotates righthad and the port engine rotates left hand
IOW, do you have two Standard LH Rotation engines?????
Confirmed!

As I mentioned earlier, you really need to see your OEM ignition curve information, and if that means contacting Crusader, that's what I'd do. I spoke to Crusader and they sent me the OEM specs and the manual - 10* BTDC and the plate on the engine also shows this. Although there are NO other numbers like curve, TA etc.
Hmmm, sounds as though they are following suit with Chrysler Marine.


In post #12, you mention "None of the issues that have been presented here were occurring PRIOR to the conversion to the electronic ignition kit". My guess would be Pertronix kits??? I called Pertronix and they said as long as it turns over its installed correctly. Kind of a dumb answer but thats what they claim. If I installed it incorrectly it wouldnt even turn over. Take it for what it is I guess.
The sensor unit must be near perfectly aligned with the magentic uniit.
Some of their kits include small shims that raise the sensor up.


Good news is, your mechanical advance units appear to be working in that a BASE of 10* offered the advance of 28* that you were seeing. Then I wouldn't need to do anythign else? If so what's my issue?? grr
Good news #2, is that both ignition distributors did the same (although that 28* needs to be further discussed, IMO).
That is correct, but only if the advance numbers are correct for your engines.

1... are you absolutely certain that the decals that you purchased are the correct decals for your balancer diameter???? Yes, I measured the diameter of the HB and it was at 7", that's the sticker I used (MDS)
If not, the degree scale will be inaccurate.
Ah... confirmed!

At idle, you'll see zero advance, however, the engine is actually seeing BASE of 10* at this point.
Now look at 1k rpm. You'll see 2* of advance. Add your BASE of 10*, and the engine is actually seeing 12*. You mean the tape will show 12* not 2* right? If so I do see this.
What you see via the strobe flash, is what the advance will be IF.... key word "IF", you are using the V notch of the timing chain cover.
Again..... See ** below.

Now look at 2k rpm. You'll see just over 10*. Add your BASE of 10*, and the engine is actually seeing 22+*. I see this - if 22* is the tape you are referencing
See above.

Now let's go to 4K rpm. You'll see that the curve has already flattened out by 3.4k rpm.
At 4k rpm, the advance is now near 22+*. Add your BASE of 10*, and the engine is actually seeing 32+*.

We'll be your "timing hot line"! LOL I really appreciate this guys - you have not idea - great learning too!! I feel like a pain posting all this stuff so many times....
I know that you do, and we're always glad to help.

Don't know what to do now to be honest. I've ordered new caps, rotors and coil wires but I'm betting that's not it. I am going to lower the base from 10 to 7 to see what happens tonight. The popping sond does NOT happen when 3k RPM in neutral, only when under load. So maybe the base is too high?? I have no idea at this point. Called Crusader, called Pertronix, got you guys, ordered new parts, etc. etc. I guarrantee you it's something simple that I'm missing!

I don't believe that you are missing anything, other than what these kits represent to me in my world. The people who has good luck with the kits, seem to love and swear by them.

If you have a budget that would allow for it, I'd replace these kits with brand new ignition distributors that use either VR or Photo Eye triggering.
There is also EST (electronic spark timing) that could be considered.
My preference would be VR triggering such as the Mallory YLM series. Mallory's YLU is photo eye.
Each are mechanical advance, and each will use the same factory curve.

EST has no mechanical advance, therefor the advance is accomplished via electronics. If you were to loose a module, you are down.

OK, here's the **.

Spark must occur before the piston reaches the top of it's travel. This is the spark advance.
TDC is top dead center of piston travel.... be it #1 or #8 or ?????.
We fire the fuel off early because the burn requires a lead time.
The ultimate burn (spelled max cylinder pressure) is to occur at 12* to 14* ATDC.... that's AFTER top dead center.
Spark advance is different for each RPM due to the delay of the fuel burn.
RPM increase..... so must the spark lead!

The reason for this, is to place the LPCP at the correct crankshaft angle (12* to 14* ATDC).
LPCP = location of peak cylinder pressure.

First.... I'm not sure that I'm following you re; this.

To be honest if the tape was orientated the other way I would not be able to hit any marks as I adjust the distrib BC it's too far away.

You should not need to look or see any further than at/near the deepest V notch in the timing chain cover "tab".
When we strobe these, the light captures the balancer marks, and the marks that we are concerned with will be right at the deepest V notch.
We will see them, but they aren't of any use when not at the deep V notch.

Perhaps think of the deepest V notch as a stationary TDC reference point, and the balancer TDC mark as a dynamic reference point that we can change by rotating the distributor housing!


Timing marks:
When the OEM balancer TDC mark is aligned with the timing chain cover deepest V notch, the #1 piston is a TDC.... and for our purposes, this will be TDC C/S (compression stroke).

Since you have now installed the decal, the full scale of the decal has now replaced the need for any of the additional degree markings on either side of the timing tab deepest V notch.

You could actually erase the smaller v notches, and it would make no difference for the way that you will now being strobing the markings.
As long as your timing light is in Standard Mode, just simply watch the degree marks that align with the deepest V notch.
Or..., when using a digitally advancing timing light, use the TDC balancer mark, and the deepest V notch.

 

[RicardoMarine]

Junior, one more thought to confuse you further! (hopefully not!)

As we strobe these marks, the entire area (tab markings, and the entire decal markings) will be lit up by the flash.
All we're concerned with will be the decal markings that align and correspond with the deepest V notch.
Anything else that you see, has no bearing on the actual timing reading.


This is a horse race photo finish.
The finish line is stationary, and the flash captures where the horse's head is relative to the finish line.
We don't care about the horse behind..... we care about the horse that finishes.

If the horse is retarded, and doesn't finish in a fast enough time, we move the track forward.
If the horse is advanced, and finishes too quickly, we move the track backwards.

The track is moved by adjusting the distributor one way or the other.

I'm going to tell you that was written by someone else, so that I don't have to take the wrath of the other members! :rolleyes:


*********************************

Side note.......
In a perfect world, ALL Marine Engines would come from the factory will fully indexed balancers.

Std LH would be like this. REV RH would be oposite.

.

 

[junior4597]

That's awesome! The horse analogy is great! I'm sure the other members will not give you crap - as you have been so helpful. So this photo, and the other you sent, would mean my Port engine will have the tape placed as the photo above - meaning that the advancing numbers will line up port side of the TDC mark on my LH rotating engine. And my STBD engine with a RH rotation will have this tape flopped - meaning the advancing numbers will line up on the (opposite) STBD side of the TDC mark. I'm pretty sure this is how I have it but I will double check when I get home. I'm picking up my new distrib caps and rotors tomorrow so I will re-look at EVERYTHING and take all this into consideration. Maybe now regretting not getting a whole new distrib setup but you live and learn. This can't be that difficult! I truley appreciate all your suggestions - as well as others!


Keep you posted!

 

[fastjeff]

..."We don't care about the horse behind"

We don't care about his behind, either! Great anaology.

Jeff

 

[RicardoMarine]

That's awesome! The horse analogy is great!

1..... meaning that the advancing numbers will line up port side of the TDC mark on my LH rotating engine.

2..... And my STBD engine with a RH rotation will have this tape flopped - meaning the advancing numbers will line up on the (opposite) STBD side of the TDC mark.

Well, the horse race thingy was a long shot, but I though, what the heck!

1..... If you are talking about aligning the ZERO on the decal with the Balancer TDC mark, then yes, that would be correct!

2..... Again, if you are talking about aligning the ZERO on the decal with the Balancer TDC mark, then yes!

See attached image

We don't care about his behind, either! Great anaology.

Jeff, I admit that was a rather silly anology of mine, but apparently it worked for him!

 

[RicardoMarine]

One more thought, and please forgive my rather crude drawings.

Not all timing tabs have a deep V notch for zero, instead, they will use a point.
Here is an example of one using a "point" for zero.

 

[RicardoMarine]

Jeff and Junior, stay tuned for my Greyhound race photo finish analogy!
(soon to be sanctioned by Mallory and Delco for GM, Chrysler and Ford Marine engines)



If that doesn't better explain it, we're moving on to Weiner Dog Races.
For this analogy, we'll be using an artist's rendition equivalent to photo finish.

 

[junior4597]

So here is the latest. I timed my engines perfectly, 10* BTDC and advance to about 28*. Took her out and under load she wouldnt kick in, get on plane or even accelerate past 2k rpm with out the carb popping. Same issues as before. This time however, I used a digital light for accuracy and even set it to 10* advance to validate it at zero. I also replaced the router, cap and coil wire - all to no avail. Been down there this morning with a friend and we tried a few more things. What I was able to do is now get her on plane and rid the popping! yay! What we did was put her in gear, accelerate to about 2k and while I accelerated he moved the distrib until it was smooth. All by ear! At this point I was able to her her on plane, advance to 3200 rpm with no popping and get what I beleive as full HP out of her!!! I still hear a little hesitation but NOTHING compared to before. The funny thing is is that we really didnt move the distrib that much - may to 12* advance at idle. I guess I'm shocked at how sensitive the adjustments can be, I mean we tweaked it very slightly. I threw the light back on it and its now around 12* BTDC. Goes to show you I could NOT use the OEM setting of 10*. Maybe these Protronix kits make that much of a difference where a few degrees makes a huge difference - I could not rely on the OEM of 10* - all done old school by ear and trial and error. Just surprised that's all. So, for now I'm much better than I was the past week, I still think there needs to be a little more adjusting with the idle and mix but for now at least it's going in the right direction.

I'm sure this issue is out there, hopefully not unique to me so I'd be curious if anyone else has had this experience before. Ricardo and Jeff - a huge thannks to you guys for all your input. I was looking at it litterally (10*) BTDC and that was ultimately my issue. Once I deviated off that make and jus tplayed with it I was able to gain momentum. I will post more once I really get her out in the open water but I wanted to shed some light on the new developments!

Again - this place is a GREAT resource!

 

[RicardoMarine]

Kirk, IMO, you need to make your progressive and TA much more important than your BASE advance.
We fire up on, and idle on BASE advance only...... beyond that, it's of little value.

I hate like heck to see you do any distributor adjustment by ear or sound. It's simply too critical to set timing this way.
Car/truck...... we can sometimes pull this off.
If you were to detonate one of your engines, and if the detonation was severe enough, you'll end up tearing your engines down.
I can't emphaize enough, the importance of this.


Kirk, is it possible that your degree decal is not correct for the balancer diameter?
We'll see the 5.7L using 6 3/4", 7" and 8" balancers.
As you can imagine, the circumference of each will vary, therefor the length between degree markings will also vary.
Much more so between the 7" and 8".

If a 7" decal was installed on a 6-3/4" diameter balancer, the degree spread (at the lessor diameter), will be too large. The end result would be that the degree increments will each be further away from the TDC mark........... of which means that a reading of 25 degrees, may actually be a true reading of 27 or so degrees.
(example only.... I've not done the math to know for sure)

Conversely, if a 6-3/4" decal was applied to a 7" balancer, the degree spread at the greater diameter, would be too close together.
Throw an 8" decall into the mix, and we have even greater concern either way.


On another note, the Pertronix sensor must be near perfectly anigned with the center of the magnetic units.
They don't go into much detail re; the alignment, but you may be able to find some "how to" information on this.

Maybe these Protronix kits make that much of a difference where a few degrees makes a huge difference

FYI: 1 degree at the distributor = 2 degrees at the crankshaft, etc, etc. The crankshaft angle is our concern.

If memory serves me, Pertronix themselves have found errors of 1 to 1-1/2 degrees within the magnetic unit (as per a post that I read here on ME.com).

I suggest:
Varify your balancer diameter again, and the degree markings.
Strobe your timing marks, and jot down the curve and full in TA numbers.
See if both engines offer the same curves.
See if these curves correlate to the OEM Crusader curves.

This can be done with NO LOAD.
The mechanical advancing systems are not sensitive to engine load or no load.

Keep us informed.

.

 

[junior4597]

I hear you Rick but one of the things you mention I am unable to verify - and that's the OEM curve. I'm almost 100% sure that these are 7" diameter HB. Now that you ask this again you are making me a little concerned as I was only able to put a tape measure on it to gauge - could be eyeballing it wrong by 1/4 of an inch, but....

So with the 7" tape applied, and when I say applied I mean I tried my darndest to make sure that zero line marked up with the HB notch. On my port engine I have the tape lined up with the numbers increasing on the port side of the TDC mark and on the STBD engine I have the numbers increasing on the STBD side of the TDC mark - per your diagrams. I have validated the OEM at 10* on idle - which by the way really needs to be around 700-750 as it stalls out any lower when in gear. One thing I cannot validate is the OEM curve from Crusader as you mention - is this a legitimate number that is available? I was under the assumption that if I am at 10* and I accelerate that the TA will just max out at a certain point. That point for me is about 28* around 3000-3200 RPM. That would mean 10* BTDC (OEM), 28* TA and the curve is 18* - if I calculated that correctly. Both engines give me these numbers. The only number I can validate is accurate is the 10* and the TA I can validate bc it doesnt advance any more. This is where I stop adjusting. When I put her under load with these settings I get engine hesitation, minor vibrations, I can hear that it's not right, at 2k rpm I get the pop coming from the flam arrestor and I'm back to sq one.

So with that I hear you about putting the light back on it and double checking the tape length and the curve but what if all that is correct? And i am assuming as I write this that it is. Then what? I can only set BASE, from there the TA I get is what I get. Are you suggesting once I'm at TA and 28* that I adjust from there, when I'm at 3k rpm? If so to what number? The latest by ear and adjusting slightly while under way was the only success I have had to get her past 2k rpm and on plane. So again, I hear you about the numbers being accurate and exact but that didn't work out so well - unless I'm doing it wrong but I'm assuming you would have caught that form me by now - based on my steps and examples. Am I missing anything? You say curve and TA is most important but how do you adjust that and to what specs do I validate that off of?? I just get the default numbers of 28* TA off my BASE setting. I can't adjust that. I don't know, I'm spinning my wheels at this point if you really dont think I should rely on my "by ear" and "manual adjustments" while under way.

 

[RicardoMarine]

........... One thing I cannot validate is the OEM curve from Crusader as you mention - is this a legitimate number that is available? I was under the assumption that if I am at 10* and I accelerate that the TA will just max out at a certain point. That point for me is about 28* around 3000-3200 RPM. That would mean 10* BTDC (OEM), 28* TA and the curve is 18*
The curve includes the 18*, but technically the 18* is your mechanical advance..... or what some call the "Progressive Advance".

- if I calculated that correctly. Both engines give me these numbers. The only number I can validate is accurate is the 10* and the TA I can validate bc it doesnt advance any more.
This is good, and means that your centrifugal system is offering Full In advance at 3000-3200 RPM.


This is where I stop adjusting. When I put her under load with these settings I get engine hesitation, minor vibrations, I can hear that it's not right, at 2k rpm I get the pop coming from the flam arrestor and I'm back to sq one.
Yeah, sump'n aint quite right here.


So with that I hear you about putting the light back on it and double checking the tape length
See below.
and the curve but what if all that is correct? And i am assuming as I write this that it is. Then what?
If it is correct, you now need to look at other possibilities.
But see below.

I can only set BASE, from there the TA I get is what I get.
Yes, unless each distributor's advancing system has been altered at one time or another.
As they are now, they are advancing via crankshaft angle to the tune of 18*.
Add your BASE of 10*, and there's your TA of 28*.
Add a BASE of 8*, and you'll have TA of 26*.
Add a BASE of 12*, and you'll have a TA of 30*
It's just math.



Are you suggesting once I'm at TA and 28* that I adjust from there, when I'm at 3k rpm?
No.... not necessarily....... unless you are unhappy with 28* @ 3k rpm.
If the TA number is correct for you engine build, then you would leave this alone.
Your BASE of 10* is should be just fine to start and idle on.


If so to what number? The latest by ear and adjusting slightly while under way was the only success I have had to get her past 2k rpm and on plane.
This suggests to me that the decal is not correct, and that what you THINK you are getting, is not so.

You say curve and TA is most important but how do you adjust that
TA can be adjusted somewhat via a change to BASE advance..... but we have limits to stay within.

I just get the default numbers of 28* TA off my BASE setting. I can't adjust that.
As said earlier, BASE advance is a result of where the distributor housing is phased with the crankshaft angle... nothing more to BASE than that.
At low idle speeds (below 1,000 rpm for example), there is NO progressive advance occurring.
At 1k rpm and above, we'll see the progressive come on.

Your TA is the sum of the complete Progressive Advance and the BASE advance.


I can't adjust that. I don't know, I'm spinning my wheels at this point if you really dont think I should rely on my "by ear" and "manual adjustments" while under way.
If money is not an object, and if you do not care about the risks of detonation, go for it!
Otherwise, I'd suggest seeing post #24 again, second paragraph.

A degree is a degree is a degree.... doesn't matter at which radius we look at a degree, it's still a degree.
What does change, is the distance from one line of degree to another line of degree at a given circumference (i.e., the result of diameter).
This is why the decal must be correct for the diameter of the circle or balancer.

All it takes is for one mistake in packaging, or one mistake from behind the parts counter, and you may end up with the wrong decal for your balancer diameter.

There is a very simple way to check this, but you must know the balancer diameter.
Draw a circle on paper of the same balancer diameter.... let's say that it's 6-3/4".
On that 6-3/4" diameter circle, divide it into 30* or 40*.... doesn't really matter.... your decal will include 40* anyway.
Take a divider and set the points one at each angle line.
Lock the divider down so it won't move on you.
Now take the divider to your balancer, place one point in the TDC mark (which is also the Zero decal mark), and see where the other point lands on the decal.
If it lands at 30* or 40*, your decal markings are good.
If not...... the decal is wrong!



Look at how many different timing degree decals this simple search result brings up.
Now look at Jeg's ad for their Precision Timing Tape.
What if they weren't packaged right?

 

[RicardoMarine]

Double post.... sorry.

BTW, maybe it's time for me to step out of the way here, and let someone else take a stab at this.
Sometimes hearing it put differently by another person can make it all "click"!

Just remember... no one has permission to use my horse race analogy.

 

[fastjeff]

Here's a tip: Seabiscuit in the forth race!

Don't know what you did to get that boat on plane, and stop the popping thru the carb, but one thing is cler: you sure as hell didn't time it right beforehand! No way will 2 degrees of timing improve torque that much UNLESS the motor was advanced way too much. (See my comment above.)

It would be interesting to have "re-timed" it (checked it with the same timing light) AFTER messing with the distributor and see where it's now at.

Finally, long as you're not running too far advanced you should be okay. If you are, holes will appear in your pistons.

Jeff

 

[junior4597]

Just wanted to give a quick update. My next steps were to verify the HB diameter, I believe I have a 7" diameter but I want to ensure I really didn't have a 6 3/4". Still waiting on that as I am out of town this week. In the mean time I contacted Crusader again about what the OEM specs would be for TA for this engine. I thought I'd post thier response here to see if anyone wanted to comment. To validate I am able to get the OEM setting for 10* at idle. What I have been struggling with is finding an OEM number for TA and maybe even the curve. Since those numbers are the most important I would have thought there would be an OEM base on it. Anyway, here is their response. More testing when I get back home and will update then.

response #1
Good afternoon sir,
I believe I spoke to you last week, and there is still not any published information. However, 28 – 32 degrees is what the full advance should be. There is not a timing curve available. I hope this information does help

response #2 (after I responded asking for more details - didn't think that was a clear answer)
Good morning sir,
The total advance does need to be close, but 1 degree off isn’t going to be seen very easily. I gave you a range due to the mechanical part of the distributor determines what the total advance should be. You just want to be sure to not exceed 32 degrees

 

[RicardoMarine]

Hi Kirk, glad to see that you posted again.

Just wanted to give a quick update. My next steps were to verify the HB diameter, I believe I have a 7" diameter but I want to ensure I really didn't have a 6 3/4". Still waiting on that as I am out of town this week. In the mean time I contacted Crusader again about what the OEM specs would be for TA for this engine. I thought I'd post thier response here to see if anyone wanted to comment. To validate I am able to get the OEM setting for 10* at idle. What I have been struggling with is finding an OEM number for TA and maybe even the curve. Since those numbers are the most important I would have thought there would be an OEM base on it. Anyway, here is their response. More testing when I get back home and will update then.

response #1
Good afternoon sir,
I believe I spoke to you last week, and there is still not any published information. However, 28 – 32 degrees is what the full advance should be. There is not a timing curve available. I hope this information does help

Dear Mr. Crusader..... thank you, but your answer is incomplete. When is this 28*-32* to occur????

response #2 (after I responded asking for more details - didn't think that was a clear answer)
Good morning sir,
The total advance does need to be close, but 1 degree off isn’t going to be seen very easily. I gave you a range due to the mechanical part of the distributor determines what the total advance should be. You just want to be sure to not exceed 32 degrees

Dear Mr. Crusader..... thank you again, but your answer is still incomplete. At what RPM should I not be exceeding 32*????

Yes, a bit of sarcasm in that to hopefully further my point!

As for the Crusader rep, and his numbers for you...... I'll say this again.
I've already explained the duration for the fuel burn, the role of progressive spark lead (for the various RPM), and the LPCP.
You know that your distributor adds a progressive advance...... or at least it's suppose to!
We can post suggested TA numbers all day long and all week long......., but until an associated RPM is given with them, they are absolutely meaningless. The Crusader rep should know this.

The curve will likely be fairly linear for this Marine engine.
This means that a TA of 28* or 30*, that becomes Full In @ 4.5K rpm (for example), may offer a progressive of only 22* @ 3k rpm.
Conversely, a TA of 28* or 30*, that becomes Full In @ 2K rpm (for example), will certainly cause detonation and engine damage.
See where this is going?????

Bottom line....... a TA number must absolutely have an associated RPM....... Period! No IF's, AND's or BUTT's about it!
Why Crusader can't provide this is beyond me!

Forgive my gruff delivery..... it's not aimed at you or anyone in particular.

*********************************

Kirk, it's tough to measure the balancer diameter while the front pulley is in our way.
I'd suggest making a make-shift tool, and use it to approximate the diameter. I say approximate, because there are only several diameters used for the SBC.
(see crude image below.... and don't laugh out loud! )

If you can make a wooden or plastic tool, similar to this below, set it for 6-3/4" tip to tip.
Lock it into position, and place it over the balancer OD.
See if it fits closely.
If not, open it up to 7", and test again.

If the balancer OD is 6-3/4", draw a 6-3/4" circle on paper. (see post #26)
Divide the circle into a 30* wedge, and mark it at the circumference (0* and 30*... or 0* and 40*).
Take a divider and set the divider to touch on zero and 30*, lock it down.
Now move the divider over to your harmonic balancer degree decal, and see if the divider dimension aligns with the zero to 30* on the decal.
Or use 40*...... 40* may be more accurate than 30*..... doesn't really matter as long as you're not doing only 5* or 10*.
(greater the reading/less chance of error)

Try this, and see what you get.