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Engine miss and new rattle developed in exhaust manifold

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I was told it was a crate engine so not sure if it was built for marine use. My neighbor passed away so I have noway to ask further.

Is there a typical advanced timing for SBC 350 that I can shoot for to optimize total timing?
Yes, and here is an example.

NOTE... this is an example ONLY. See your OEM specs for your engine.



Otherwise, all i know to do is set the initial timing for maximum engine vacuum @ 550-600 RPM per the manual.
I think that your manual is referring to a low speed fuel/air mixture adjustment.
The low speed metering is adjusted as to achieve maximum manifold pressure.
Any change to BASE advance will also affect idle RPM.

Keep in mind that any change to BASE advance creates the same change to the Progressive and Total Advance.

I get it, its the only way to be 100% sure. PIA, but I see your point since I do not know for sure.
You will gain "Peace of Mind" if you do this!

See post #18, 23 and 27 in this thread from November 2017.
http://www.marineengine.com/boat-fo...-a-new-delco-voyager-est-distributor-question
 
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Originally Posted by swc65I get it, its the only way to be 100% sure. PIA, but I see your point since I do not know for sure.
You will gain "Peace of Mind" if you do this!

See post #18, 23 and 27 in this thread from November 2017.

http://www.marineengine.com/boat-for...butor-question

Interesting you say that, because it is the peace of mind I want when on the water. Its my relief valve and I have to be worrying about the boat when I'm trying to enjoy the sunset. Definitely worth my time. I found the post very helpful and am slowly piecing it all together. There really are no mysteries are there. Just process of elimination... I've attached my OEM timing curve I normally cruise between 2500 and 3000 and get up to 3500, rarely go WOT but like to every now and then. :)mad:trying to post my engine timing specs,I find this site frustrating when trying to post pics. Sometimes works like a charm and sometimes it appears to upload and nothing happens. Not sure if it my machine or the ME site.)

So, some more first timer questions about removing belt pulleys, installing the degree wheel and replacing pulleys.

  1. Does anything else need to come off first before adding degree wheel to accommodate a 14" wheel that I'm planning to get from a speed shop or online. I measured below the deck to insure no obstruction of the wheel but I didnt think about the power steering pump or water pump.
  2. How do I keep engine from turning when removing center bolt holding the pulley to the balancer? Then same when removing wheel and reinstalling pulleys?
  3. The degree wheel will bolt to balancer, using same bolt that held pulley, correct? I assume it comes with a washed to take the space of the pulley.
  4. Once degree wheel is on balancer, do I rotate the TDC mark on balancer to 30 degrees before or after as a starting point to insert the Positive stop?
  5. Does it matter how far into the the cylinder the stop is adjusted?
  6. Any other tips or gotchas I may run into while performing this? , For example, should ?I expect the pulleys to slip off fairly easy or is a puller required? I always seem to be the guy that does not have what I need when I need it and it sucks any working efficiency right out of the job to be done. Any tips that reduce my "discovery process" are always appreciated.

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Interesting you say that, because it is the peace of mind I want when on the water. Its my relief valve and I have to be worrying about the boat when I'm trying to enjoy the sunset. Definitely worth my time. I found the post very helpful and am slowly piecing it all together. There really are no mysteries are there. Just process of elimination... I've attached my OEM timing curve I normally cruise between 2500 and 3000 and get up to 3500, rarely go WOT but like to every now and then. :)mad:trying to post my engine timing specs,I find this site frustrating when trying to post pics. Sometimes works like a charm and sometimes it appears to upload and nothing happens. Not sure if it my machine or the ME site.)

So, some more first timer questions about removing belt pulleys, installing the degree wheel and replacing pulleys.

1... Does anything else need to come off first before adding degree wheel to accommodate a 14" wheel that I'm planning to get from a speed shop or online. I measured below the deck to insure no obstruction of the wheel but I didnt think about the power steering pump or water pump.
A 14" diameter degree wheel will have a 7" radius. Do you have enough room for a radius that large?


2....How do I keep engine from turning when removing center bolt holding the pulley to the balancer? Then same when removing wheel and reinstalling pulleys?
Be creative.

3..... The degree wheel will bolt to balancer, using same bolt that held pulley, correct? I assume it comes with a washed to take the space of the pulley. The crankshaft pulley is held in place with 3 bolts and the center crankshaft bolt. The degree wheel will have one hole only.
You will be using the center crankshaft bolt for the degree wheel.





4.... Once degree wheel is on balancer, do I rotate the TDC mark on balancer to 30 degrees before or after as a starting point to insert the Positive stop?
The depth adjustment of the PPS will determine the amount of degrees that the piston is short of reaching TDC.
In other words, the more that you extend the PPS into the cylinder, the greater the degrees between your CW and CCW rotational stops.
The goal would be 25 to 30 degrees in either direction.
This equates to more accuracy.



5.... Does it matter how far into the the cylinder the stop is adjusted?
Yes... see above.


6.... Any other tips or gotchas I may run into while performing this? , For example, should ?I expect the pulleys to slip off fairly easy or is a puller required? I always seem to be the guy that does not have what I need when I need it and it sucks any working efficiency right out of the job to be done. Any tips that reduce my "discovery process" are always appreciated.




Since I believe that you are not quite understanding this (no offense), I have a suggestion for you:

Forget the use of the degree wheel and temporary pointer.
Instead, use the circumference of the harmonic balancer against the timing tab ZERO.
(see my image below)

Doing so will at least allow you to verify the accuracy (or inaccuracy) of the OEM TDC slot in the harmonic balancer.
If you see a discrepancy (due to the outer ring having slipped on the inner hub), your new paint pen TDC mark will take precedence over the OEM TDC slot.


PPS for true #1 TDC using harmonic balancer  .jpg



If you do see a discrepancy, it will mean that the inner/outer hubs have slipped on one another.
If so, take a punch and mark each hub.
If after hours of running the punch marks do not remain aligned, it will mean that the hubs are still slipping

 
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It does. I understand using the degree wheel concept. Makes sense, I was merely thinking through the steps. I researched a number of my questions. Seems there are some creative folks out there... There rope trick kinda blow my mind. I would never put anything in my cylinder. The best idea I was was a strap wrench in I hold the pulleys.

I’ll check existing mark for accuracy then go from there. Learning a lot on this task. I’m sure I’ll be back for more help.
 
It does. I understand using the degree wheel concept. Makes sense, I was merely thinking through the steps. I researched a number of my questions. Seems there are some creative folks out there... There rope trick kinda blow my mind. I would never put anything in my cylinder.
The nylon rope trick is safe.

The best idea I was was a strap wrench in I hold the pulleys.


I’ll check existing mark for accuracy then go from there. Learning a lot on this task. I’m sure I’ll be back for more help.


I just found another image that I had made several years ago that I had forgotten about.

PPS TDC without using degree wheel and pointer.jpg
 
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I looked in my OMC shop manual from 1988 which is older than yours but, for the 5.7 King Cobra they gave:
8* base timing + 21* full centrifugal advance @ 3,000 rpm, for a total of 29*. If you can set it up with the 8* at idle and then use an advance timing light to check full centrifugal advance with it in the water (I prefer not to rev that high on the water hose, but if you have very good water pressure and good muffs you probably can) you will be close enough.
 
I looked in my OMC shop manual from 1988 which is older than yours but, for the 5.7 King Cobra they gave:
8* base timing + 21* full centrifugal advance @ 3,000 rpm, for a total of 29*. If you can set it up with the 8* at idle and then use an advance timing light to check full centrifugal advance with it in the water (I prefer not to rev that high on the water hose, but if you have very good water pressure and good muffs you probably can) you will be close enough.
Thanks Lou, petty close to mine. I found this in my manual. So I take from this that he original ignition (Prestolite) would create this spark advance pictured below. If just occurred to me that, if it is the ignition system that provides the spark advance, then shouldn't I be able to get a similar table from Pertronix for a SBC? I understand that all of this is predicated on the fact that I have an accurate TDC mark on my balancer. I'll be checking on that my next time out when I install the new marine starter.

Yes, and I do have the boat on a lift so i can get it in the water. So revving the motor is not an issue.

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swc65 said:
then shouldn't I be able to get a similar table from Pertronix for a SBC?
This is actually referred to as an ignition advance "curve" or "curve graph".
Do not rely on anything other than your OMC OEM ignition advance specs for your engine.
Automotive specs are not the same.


I understand that all of this is predicated on the fact that I have an accurate TDC mark on my balancer.
Yes.... absolutely!


swc65, there is no need to use a digitally advancing timing light.
If a digitally advancing timing light is of substandard quality, the electronics and/or the algorithm of the electronics may not be 100% accurate.

The good ole strobe style timing will be your best bet since you will now have a marked off harmonic balancer.
With this type and method, you will be able to see Real Degrees in Real Time.


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Do not rely on anything other than your OMC OEM ignition advance specs for your engine.
In my case OEM ignition wasPrestolite according to manual. The current ignition is Pertronix. I assume it was replaced when the engine was replaced.

Do you still recommend timing advance in manual? Isn’t the timing advance a function of Ignition system? And if so couldn’t Pertronix provide me a timing curve that is more representative for my engine/ Ignition combination?
 
Your timing advance is not determined by the type of ignition system you are using (ie either the original points system or electronic--Petronix in this case) it is totally a function of where you set your base timing and the advance that is allowed by the centrifugal weights and springs in the original Prestolite distributor. I am assmuming what you have is a Prestolite that someone removed the points from and then installed the Petronix, correct? If that's the case then what I said above I believe to be true. The OEM set it up for a reason using the compression ratio, carb jetting, theoretical loads on the engine and fuel octane used.
 
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No, the distributor is Pertronix, not a retrofit kit. I suspect it was replaced when the crate engine installed. My OMC manual references Prestolite Electronic Ignition.

Your comments above are what cause me to think the ignition spark advance is co trolled by the module in the distributor. Am I correct. And if so then don’t I need spark advance guidance from Pertronix for a 350 SBC with Holley 650 carb.

if the correct answer is “ use my manual” the. I’m good with that but struggling to understand how anything in the manual can relate to a different engine with different ignition.

Hope to work on it this week end.
 
This image is from post #10. This is your distributor, correct?

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Those springs shown are connected to the centrifugal weights. These provide the advance as the rotation speed increases. Each of these weights needs to be able to slide outward at the end furthest from the spring. Do they slide freely and return to the position shown when released?
 
Sorry, missed this. Yes this I my distributor and I cleaned all the rust and they operate freely now.

But the real question is do I use the Advance/RPM values In my OMC manual which shows Prestolite ignition. The distributor above is Pertronix.

Can I assume all distributors with electronic ignition are same?
 
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I think I would run the engine and make note of the advance at some of the various RPM intervals in the manual. Someone here will (probably) be able to tell you if the advance is OK.

For the record, on my boat, I do use the advance set-back feature of my timing light by bringing the balancer mark to the zero notch at higher RPM.

Good luck.
 
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Sorry, missed this. Yes this I my distributor and I cleaned all the rust and they operate freely now.

But the real question is do I use the Advance/RPM values In my OMC manual which shows Prestolite ignition. The distributor above is Pertronix.
Short of any EST system......., whether Prestolite, Mallory, Pertronix, Accel, MSD or other, the triggering mechanism (contact points, VR, photo-eye or Hall Effect) has ZERO to do with the mechanical advance.
The triggering portion creates coil saturation and the collapse of the field that produces the high tension voltage.
The mechanical advancing mechanism creates the curve and will determine when the system is Full In.


Can I assume all distributors with electronic ignition are same?
NO.... you will see a slight variance between them.


Your SBC is most likely fitted with the GM Full Dished pistons.
If so, this makes that engine more prone to Ignition Induced Detonation, particularly when used in a Marine application.

In my opinion, the important aspect of this will be what the system is offering in the 3,200 + RPM range.

I would steer clear of heavy loads in the 2,000 to 3,000 RPM range.

We have two efficient speeds at which to operate:

...... hull speed.
...... planing speed.

anything in between will be rather inefficient.

Recap:

Verify true TDC. If the TDC marks are inaccurate, your ignition timing will be just as inaccurate.

If your OEM work shop or service manual gives you an advance curve and TA, use it.

Time the engine for not only BASE/Initial, but also verify your Total Advance and the RPM at which it occurs.


If you own a high-end digitally advancing timing light, and if you trust it and know how to use it, go ahead.

If you do not own one, and if your balancer is marked off correctly, then use a standard strobe style timing light and view your advance in Real Degrees in Real Time.


By the way, when you are ready to test your ignition system advance...... you can safely operate your engine on the garden hose water muffs, and bring RPM up to 3,200 + (for several seconds) without causing any damage.
When you read that this is a NO NO, it is a disclaimer by the OEM.

Just make sure that the muffs are installed correctly and are secured well, and that you have plenty of garden hose water supply.
You will be at your Full In RPM for only a second or two.


.
 
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Rick, what do you mean by this statement? "I would steer clear of heavy loads in the 2,000 to 3,000 RPM range." Do you mean load as in passengers and weight?

Can you define Hull speed? I assume Plane Speed is the speed at which the boat achieves plane.

Pertronix got back to me with an attachment, I tried to upload but unsuccessful so I pasted of couple screenshots. If you know why let me know, the file size is 1.2MB. Maybe file is too large...

With the silver springs, the distributor offers ~23 degree advance (estimating from chart) at 3200 RPM. Adding to a base of 8 degrees, that should result in total timing of 31 degrees BTDC total timing 3200 RPM.

I found another nugget in the Pertronix documentation that would seem to open another can of worms. I'd rather not explore it but for the sake of education and full disclosure, I'd like your thoughts. I did replaced my ESA module a couple years ago. The symptom at the time was the engine would start sputtering and cutting out at higher RPM, I don't recall the brand, I may have even posted on this forum. Anyway, my boat has never had the diodes or resistors per the Pertronix instructions.

Pertronix offers wiring specifically for OMC Sterndrives using diodes and resistors. I'm not going to bother with the diodes and resistors until I confirm my TDC mark and observe the total advance at 3200 to 3500 RPM. I'm unsure if the OMC wiring if for Pertronix Coils specifically or for all coils. I have a reply into Pertronix asking for clarification.


Do I adjust the distributor until I get the desired total timing at a specific RPM?


  • I follow the Pertronix chart below, the advance at 3200 RPM is maybe 23 degrees? Adding base timing of 8 degrees for a total of ~31 degree Total Advance @ 3200 RPM.


  • The OMC Manual shows advance of ~26 degrees @3130 RPM, Adding base timing 8 degrees for a 34 degree Total advance at 3130.

I am more inclined to use the Pertronix data since that is the distributor that I have.

Hypothetical:Assuming I use Pertronix values, is the action correct?
  • Observed a timing at 3200 RPM is 34 degrees BTDC.
  • Action: Retard Timing at 3200 to 31 degrees.
  • If I retard timing at 3200, I assume timing will also be retarded at idle.

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Rick, what do you mean by this statement? "I would steer clear of heavy loads in the 2,000 to 3,000 RPM range." Do you mean load as in passengers and weight?
No.... loads as in engine loading.

At between 2,000 and 3,000 RPM, most hulls are above "hull speed" and yet are below "planing speed".
It is an inefficient speed to be operating at, and is a range whereby detonation is more likely to occur.


Can you define Hull speed?
Hull speed or displacement speed is the speed at which the wavelength of a vessel's bow wave is equal to the waterline length of the vessel.
In other words, it is the speed at which the hull is not yet ineffectively pushing massive amounts of water.
Each hull is different.



I assume Planing Speed is the speed at which the boat achieves plane.
Yes, it refers to the hull's attitude.
It is most efficient at slightly above the attitude at which the hull begins to plane out.

Pertronix got back to me with an attachment, I tried to upload but unsuccessful so I pasted of couple screenshots. If you know why let me know, the file size is 1.2MB. Maybe file is too large...
Go to "Tiny Pic dot com" and reduce the size.

With the silver springs, the distributor offers ~23 degree advance (estimating from chart) at 3200 RPM. Adding to a base of 8 degrees, that should result in total timing of 31 degrees BTDC total timing 3200 RPM.
with your math, those numbers would appear to be correct.
However, with a build using what are most likely the GM Full Dished pistons, I would cut this back to 28/29 degrees @ 3,200 RPM.
The fuel quality (octane rating) will influence this also.

I would never swap springs under the guise that each spring kit offers a curve of a certain value.
As well intended as the company may be, the governing spring values may not be consistent.
This is where the Sun, Allen or King machine comes into play..... or, you do an "On Engine" test and plot the curve out on graph paper.
Any needed change would require tweaking of the spring supports.

I found another nugget in the Pertronix documentation that would seem to open another can of worms. I'd rather not explore it but for the sake of education and full disclosure, I'd like your thoughts. I did replaced my ESA module a couple years ago. The symptom at the time was the engine would start sputtering and cutting out at higher RPM, I don't recall the brand, I may have even posted on this forum. Anyway, my boat has never had the diodes or resistors per the Pertronix instructions.
Early on, the "diode fix" was used (Stewart Hastings goes into deal on this).
Later, an ESA module came out for use with electronic ignition systems.


Pertronix offers wiring specifically for OMC Sterndrives using diodes and resistors. I'm not going to bother with the diodes and resistors until I confirm my TDC mark and observe the total advance at 3200 to 3500 RPM. I'm unsure if the OMC wiring if for Pertronix Coils specifically or for all coils. I have a reply into Pertronix asking for clarification.
I believe that Pertronix recommends a certain ignition coil for their systems.


Do I adjust the distributor until I get the desired total timing at a specific RPM?
Yes... but keep in mind that this may affect where your BASE advance is.
Remember...... with a mechanically advancing system, any change to BASE creates an equal change to the TA, and visa-versa.



  • I follow the Pertronix chart below, the advance at 3200 RPM is maybe 23 degrees? Adding base timing of 8 degrees for a total of ~31 degree Total Advance @ 3200 RPM. Like said, I would cut this back to 28/29 @ 3,200 RPM.


  • The OMC Manual shows advance of ~26 degrees @3130 RPM, Adding base timing 8 degrees for a 34 degree Total advance at 3130. I guess you could roll the dice!

I am more inclined to use the Pertronix data since that is the distributor that I have.

Hypothetical:Assuming I use Pertronix values, is the action correct?
  • Observed a timing at 3200 RPM is 34 degrees BTDC. In my opinion......... unless your engine was built with a Q/E combustion chamber and used with high octane fuel, that would be excessive!
  • Action: Retard Timing at 3200 to 31 degrees. Perhaps still a bit excessive!
  • If I retard timing at 3200, I assume timing will also be retarded at idle. Correct. As noted above, with a mechanically advancing system, any change to BASE advance creates an equal change to the TA, and visa-versa.

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RicardoMarine;682139[COLOR=#000000 said:
ertronix offers wiring [/COLOR]specifically for OMC Sterndrives using diodes and resistors. I'm not going to bother with the diodes and resistors until I confirm my TDC mark and observe the total advance at 3200 to 3500 RPM. I'm unsure if the OMC wiring if for Pertronix Coils specifically or for all coils. I have a reply into Pertronix asking for clarification.
I believe that Pertronix recommends a certain ignition coil for their systems.
They do, I confirmed that my coil is with in their tolerance, just not "optimal".

RicardoMarine said:
If I retard timing at 3200, I assume timing will also be retarded at idle. Correct. As noted above, with a mechanically advancing system, any change to BASE advance creates an equal change to the TA, and visa-versa.

This sounds iterative. So , do I go back and forth from TA to Base and adjust distributor until I get both numbers where I want them.
For example 28/29 degrees 3200 RPM and 8 degrees at 550-600 RPM? If they TA and Base are interactive will I achieve a point where I get what I want at both ends? Sorry for dumb questions but I have a calibration back ground with instrumentation and am aware of the interaction of older analog electrical components so I'm drawing an analogy but not sure if I'm on the right path.

Thanks as always.
 
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They do, I confirmed that my coil is with in their tolerance, just not "optimal".

This sounds iterative. So , do I go back and forth from TA to Base and adjust distributor until I get both numbers where I want them.

Yes and No....
Yes.... you will go back and forth a bit while looking at the TA and BASE.
No..... you will not be able to get both numbers where you want them to be without disassembly and internal adjustment.

** Reason:
Let's say that your TA target is 28* @ 3,200 RPM.
Let's say that you strobe the marks @ 3,200 RPM, and find that your TA is at 32* (4* higher than you want it to be).
Now you will go back to idle speed and retard the BASE by 4*.
Go back to 3,200 RPM again, and verify that you have your 28* TA. (32* - 4* = 28*)
When you go back to idle RPM, if BASE is within reason (6 to 10*) all is good.

However, if you reduced BASE by 4* ( in order to achieve TA of 28* @ 3,200 RPM), and if BASE is NOW only 4*, it's time to remove the distributor and take it in and have it adjusted.


Another way to look at it:
Let's say that you have two marks on the ground that are 20' apart.
let's say that you lay a 20' 4" rope out on the ground and you want both ends of the rope to touch a mark.
You pull the rope towards yourself so that it aligns with the one mark that is the closest to you.
The other end of the rope is not touching the mark .... it's actually 4" too long.
Do you pull the rope further towards yourself by 4", or do you shorten the rope by 4" to equal 20'?

Answer: you shorten the rope.

With regard to the hypothetical advance scenario above (**), you shorten the advance by adjusting the flyweight limits (if equipped with a limiting adjustment).
 
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I understand. I noted the following in the Pertronix documentation. This would be the methods to "shorten the rope" I presume. I will check it out and keep my fingers cross that I 8-29 degree range with not modification. I would have to order parts and instructions from Pertronix.

What do you think about the second bullet below? I would not know how much more initial timing to use. Sounds like the more base advance the more load on the starter so is too much advance indicated if engine barely turns over. Seems arbitrary but I guess I figure it out. I'll be conservative with distributor movement.



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I understand. I noted the following in the Pertronix documentation. This would be the methods to "shorten the rope" I presume. I will check it out and keep my fingers cross that I 8-29 degree range with not modification. I would have to order parts and instructions from Pertronix.
................ or, take the distributor to a shop with a Sun, Allen or King machine!


What do you think about the second bullet below?
I'm not following you on that one!


I would not know how much more initial timing to use. Sounds like the more base advance the more load on the starter so is too much advance indicated if engine barely turns over.
If the engine "bucks" when starting, yes.... excessive BASE advance could be a problem.
However, if I'm reading your post correctly, you would be cutting back on BASE as to reduce the TA......... yes/no?

Seems arbitrary but I guess I figure it out. I'll be conservative with distributor movement.


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....However, if I'm reading your post correctly, you would be cutting back on BASE as to reduce the TA. yes/no

My comment was related to the second bullet of the Pertronix instructions which indicates to use as much initial timing as possible without excessive starter load. It looks like my screen shot of he Pertronix instructions did not load. I'm just insuring I understand the process. I don't know what action I'll need regarding timing advance until I can accurately read the total timing at RPM. But, now I have a much better feel for the process.

I had to google a Sun machine.:D Looks old school. Not even sure where I'd find one in Dallas. I assume hot rod shops are the few folks that work on distributors these days. Hopefully I will not need one.

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My comment was related to the second bullet of the Pertronix instructions which indicates to use as much initial timing as possible without excessive starter load. It looks like my screen shot of he Pertronix instructions did not load. I'm just insuring I understand the process. I don't know what action I'll need regarding timing advance until I can accurately read the total timing at RPM. But, now I have a much better feel for the process.
The Pertronix bullet point #2 was apparently written by a person with no Marine Engine experience or knowledge.

In my opinion, bullet point #3 should be executed while using a distributor machine.


As per bullet point #4, if you were to use the copper (not "cooper") springs, and if they indeed created that curve shown (plus BASE advance), you will damage your engine.
If you were to use the black springs, and if they indeed created the curve shown, your engine will not produce any power.


Bullet point #5 mentions vacuum lock out. Vacuum advance is NOT used on the Marine Engine. The mere mention of that leads me to believe that the instructions are very generic, or even automotive related.


I had to google a Sun machine.:D Looks old school. Not even sure where I'd find one in Dallas. I assume hot rod shops are the few folks that work on distributors these days. Hopefully I will not need one.
Yes, the Sun, Allen or King machines are "old school", but are invaluable for people like yourself with a mechanically advancing ignition system..... especially when it comes to changing flyweight governing springs and/or limit stops.




Please understand that your SBC engine build (piston profile, combustion chamber volume, camshaft profile, fuel octane rating, etc.), along with the anticipated Marine Engine Loads, are all part of what determines the ultimate ignition advance curve........... NOT the distributor nor the make of the distributor!

The second sentence in Bullet point #1 is the best advice that Pertronix has offered.

 
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I think it’s time I seek a mechanic that I can trust. I was able to determine that my original timing mark was within 2.5 degrees of original, My method could be within the range of error. I printed off a degree wheel and stuck it to my balancer and used PPS.

When I tried check the base timing to 8 degrees BTDC, The engine was running very rough and it was herd to see the marks. It seemed it was moving around alot or maybe it was just me reading it but the engine miss was making it difficult for me. I tried new plugs but no difference. I didn’t want to rev the engine in that condition. Concerned that I may damage something.

After the engine ran for a while while experimenting with the timing, I was observing the the timing be I checked a couple of plugs and they seemed to have more coarbon than I remembered. So I started second guessing my carb rebuild. I wanted to eliminate plugs so I bought new. All I could get local auto parts store were AC plugs number R43TS, I took out CR43TS but I wanted to see if that would make a difference and it didn't. either of the parts I looked up up for my engine on this website.They didn't carry

Interesting comments on Pertronix. I’ve thought multiple times that perhaps problem is in ignition. But I’ve done test per their procedures and it falls within spec. I’ve tested resistance for the ground which they told me is most common issue. They say it can’t be more than 0.2 ohms, mine is 0.2.

I also checked voltage at coil positive with key on not running and it is in the spec they gave me. Minimum voltage at coil + should be Minimum 8 VDC key on. Mine was over 10 VDC but less that the 11.5 VDC normal Although it was below the normal for their spec it was above minimum. I was not confident checking the coil while cranking or running because the negative of the coil was grounded to engine as was the positive side of the coil as per their attached instructions. Pasted below.


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I think it’s time I seek a mechanic that I can trust.
Great idea.
I would suggest seeking one with extensive Marine Engine ignition system experience.


I was able to determine that my original timing mark was within 2.5 degrees of original, My method could be within the range of error. I printed off a degree wheel and stuck it to my balancer and used PPS.
See posts #33 and #37 again.
Use that method that rid yourself of the 2.5 degree discrepancy.

Ignition timing is based on crankshaft angle.
A 2.5 degree TDC mark error at the crankshaft will be a 2.5 error with regard to the ignition timing.


When I tried check the base timing to 8 degrees BTDC, The engine was running very rough and it was herd to see the marks. It seemed it was moving around alot or maybe it was just me reading it but the engine miss was making it difficult for me. I tried new plugs but no difference. I didn’t want to rev the engine in that condition. Concerned that I may damage something.
If when checking/setting BASE advance, and if the reading jumps around, it is typically an indication of weak governing springs that are not holding the flyweights in during idle RPM.
Typically, we should not see any mechanical advance until a few hundred RPM above idle speed.


After the engine ran for a while while experimenting with the timing, I was observing the the timing be I checked a couple of plugs and they seemed to have more coarbon than I remembered. So I started second guessing my carb rebuild. I wanted to eliminate plugs so I bought new. All I could get local auto parts store were AC plugs number R43TS, I took out CR43TS but I wanted to see if that would make a difference and it didn't. either of the parts I looked up up for my engine on this website.They didn't carry

Interesting comments on Pertronix. I’ve thought multiple times that perhaps problem is in ignition. But I’ve done test per their procedures and it falls within spec. I’ve tested resistance for the ground which they told me is most common issue. They say it can’t be more than 0.2 ohms, mine is 0.2.

I also checked voltage at coil positive with key on not running and it is in the spec they gave me. Minimum voltage at coil + should be Minimum 8 VDC key on. Mine was over 10 VDC but less that the 11.5 VDC normal Although it was below the normal for their spec it was above minimum. I was not confident checking the coil while cranking or running because the negative of the coil was grounded to engine as was the positive side of the coil as per their attached instructions. Pasted below.

The - side of the coil is only taking to Negative during coil saturation (once per cylinder firing).
When that circuit is released (again, once per cylinder firing), that is when the high voltage discharges.


Good luck. Hopefully you'll get it sorted out soon.




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Thanks
I went out this morning to look at it again. This time I saw more stable marks with the strobe and was able to adjust down to ~8 degrees BTDC. When throttling up to ~3200 RPM I observed TA of around 34-36. I am using the original timing mark if I did make a mistake with the 2.5 degrees then that can be taken into account. Either way, that is way to high. I also note that when I tighten the distributor, the timing always advances a few degrees.

When I retard down to 8 BTDC I feel a subtle bump on the distributor. This makes me very nervous so I left it at about 10 degrees BTDC

I called mechanic and he is pointing be back to fuel pressure as source of the miss and the fact that the brand new plugs fouled with carbon after a day of very little run time on the lift while I was experimenting with the timing. I'd like to test the fuel pressure under load assuming I can get it to run on the water. What would you recommend.

Trying to eliminate all non issues prior to having the mechanic come out.
 
I cannot emphasize enough the importance of locating true TDC. That would be my first priority.


Also, I think that I have exhausted my efforts in helping you.


As I see it, you have two choices:

Continue attempting to experiment and risk losing part of the upcoming boating season.
At your own risk, play around with the flyweight governing springs and use caution.
See if your mechanic friend can help you.


Or.....

Find a shop who has a Sun, Allen or King machine..... they are out there!
Pull the distributor out and take it to them and have them make the corrections using a known-to-be-good Marine ignition advance curve.
Re-install, set BASE advance, check TA, and go out and enjoy the boating season.



I wish you the best!
 
Thanks, appreciate the help! I do feel the frustration of not being on the water. I think the original timing mark is very close. While getting a feel for the procedure, I found that after turning CCW, my crank bolt would loosen and I had trouble turning the engine. I finally worked up a make shift strap wrench to get the bolt torqued. Using the degree wheel and a pointer I achieved a 2.5 degree delta from the original.

I've called a couple of my go to auto mechanics to find shops with distributor machines and no luck so far. I'll keep looking...
 
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