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timing a new delco voyager est distributor question

realcaptron

Regular Contributor
I'm a dummy. Cant quite understand total timing but here is first question. The new delco distributors I just installed include a timing "shunt" to be plugged in to set base timing. I get that. But when I want to increase rpm to 3000 rpm to check total timing, do I remove the shunt or leave it in place. Also, I am planning on timing my 454s at 3000 rpms to 30 degrees. Does that sound about right? Does that mean I simply want to set my timing light advance to 30 degrees and align it to the 0 mark on timing tab? If it is off at 3000 rpms, do i return to idle to make distributor adjustment and then back up to 3000 rpms to check adjustment? Thank you.
 
You use the shunt to set the base timing usually at 8 Deg BTDC , shut the motor off, and remove the shunt.
To check total advance timing some you a dial back light and some use tape . Being that the timing mark will move CCW and hide itself I paint 4 lines CW the width of a nickle from the harmonic balancers line.. That about 8 degrees each.
Start the motor ,go to 3000 rpm and just shoot the timing , read the 4th line
 
Like BD said, the shunt is only used for the base timing - the shunt disables the 'advance function' that's built into the module.

to check the total advance, dont use the shunt.

Using the advance function on a timing light, what you described is appropriate. Would be a good idea to verify the advance function to ensure its accuracy - not all are created equally....
 
Like BD said, the shunt is only used for the base timing - the shunt disables the 'advance function' that's built into the module.

to check the total advance, dont use the shunt.

Using the advance function on a timing light, what you described is appropriate. Would be a good idea to verify the advance function to ensure its accuracy - not all are created equally....

Thanks Mark and BD...so here is update
I just attempted timing on both motors. Starting with starboard which is the one burning too much fuel. I established tdc by bumping it until balancer mark lined up with 0 on timing tab and rotor pointing at #1. I started engine and warmed to idle at 700. Hooked up light and shunt in distributor and it was close but minor move to 8 * btdc. Removed shunt and increased to 3000 rpm. Checked advance with advance dial light and found it at 18* advance.
Internet is telling me some people experiencing advance limiting at 20* with these delco ests.
Decided to check port engine (this one is putting like kitten). Same procedure, set to 8* at idle with shunt, removed shunt and increased to 3000 rpm and read this one at 20* advance at 3000.
What am I doing wrong?
 
probably nothing, to be sure the dial back light is set and working correctly paint 4 white lines and use a regular light at 3000 , count the lines at "0"
 
Have you checked for true TDC with a piston stop tool? Old vibration dampers can give you a false timing mark confirm true TDC then you can get the proper base timing and total advance readings. (Very important to check)
 
Have you checked for true TDC with a piston stop tool? Old vibration dampers can give you a false timing mark confirm true TDC then you can get the proper base timing and total advance readings. (Very important to check)

to be honest, i have not done that....but let me say I'm in a bit of a pickle because with v drive configuration, engines facing backward, my #1 on starboard side is on the outboard side of engine up against a fuel tank. I can barely even touch the spark plug wire to pull it off, let alone get a socket and wrench on that plug. Not knowing how long these plugs have been in there and how stubborn might be, I am extremely reluctant to attempt removal just yet for fear of snapping it off or stripping it out going back in. At least right now I have a running boat. I know eventually I will have to tackle it, but it might be the day I have to bite the bullet and pull manifolds off. That will also be a dicey removal, but once removed, I could more easily replace all the plugs. You know...I am still struggling with grasping the concept of "total advance". If total advance is merely the advance reading at 3000 rpms or so with a dial back light, then why even bother setting initial timing at idle with shunt inserted? I have seen some posts suggesting just set 3000 rpm timing and disregard idle timing, and I also have seen the opposite...some saying set the idle advance with shunt and don't worry about total advance because it is automatically done by the est distributor.
I have to admit that my engines were both starting and running better with the HEI distributors that were in there when I bought the boat. I only changed them out because they were not marine rated .
 
Its a common characteristic of the non-ECU-controlled EST systems....set the timing where you want it at the RPM you plan to use most often. that way you should be max output from the engine (the reason most set it at cruise).

Verifying the balancer is good if you don't know the history...though, to be honest, I haven't seen too many marine BBC's with slipped balancers. You have two easy options: 1) use the TDC mark stamped in the flywheel (by the factory) and compare it to the balancer, and 2) look at the firing order and pick the cylinder that lines up with #1 (going on memory, #6 on a normal LH engine)...you can use the piston stop there and get the same balancer position....
 
Its a common characteristic of the non-ECU-controlled EST systems....set the timing where you want it at the RPM you plan to use most often. that way you should be max output from the engine (the reason most set it at cruise).

Verifying the balancer is good if you don't know the history...though, to be honest, I haven't seen too many marine BBC's with slipped balancers. You have two easy options: 1) use the TDC mark stamped in the flywheel (by the factory) and compare it to the balancer, and 2) look at the firing order and pick the cylinder that lines up with #1 (going on memory, #6 on a normal LH engine)...you can use the piston stop there and get the same balancer position....

Thanks Mark, you have been very helpful and I appreciate it big time. If I can ask you (or any other contributors) a question off topic, with twin 454s pushing an 18,000 lb 32' boat ( slight v, almost flat at stern, rounded chines) if I said that I think the starboard motor is burning 2 gallons/mile (.5 mpg) and the port side is doing more like .75-1mpg, obviously I need to improve the starboard side, but that is resulting in a combined burn of perhaps 3 gallons per mile at a very leisurely 1500 rpm (8.5mph per gps)...does that sound remotely feasible burn rate..or something is terribly wrong?
 
I haven't looked at my data in a while so can't help with specific values in your units (I keep all my data in GPH as our load varies from trip to trip)...that said, the burn rates between a pair of counter rotating engines should be a lot closer than what you are seeing....and it would be good to ID and resolve the issue(s) in the thirsty one.....using too much fuel will eventually give you diluted oil and reduced engine life....as well as make your fuel bill hurt more than it should.....

our engines don't start to deviate in the fuel burn curves til ~ 2500RPMs....and its proportional to the different loads they see per the manifold vacuum...not matter how much you try, they will vary rarely 'breathe' in an identical manner...even within an engine, we can see differences (minor) between the front pair of plugs and the rear set....
 
I haven't looked at my data in a while so can't help with specific values in your units (I keep all my data in GPH as our load varies from trip to trip)...that said, the burn rates between a pair of counter rotating engines should be a lot closer than what you are seeing....and it would be good to ID and resolve the issue(s) in the thirsty one.....using too much fuel will eventually give you diluted oil and reduced engine life....as well as make your fuel bill hurt more than it should.....

our engines don't start to deviate in the fuel burn curves til ~ 2500RPMs....and its proportional to the different loads they see per the manifold vacuum...not matter how much you try, they will vary rarely 'breathe' in an identical manner...even within an engine, we can see differences (minor) between the front pair of plugs and the rear set....

You, sir are one of the most helpful guys I've encountered over the years. I concur on finding the issue on starboard motor. I'm thinking this is not a new phenomenon altogether. The oil in the thirsty motor looks a little thin and darker in color than that on port engine, which looks perfect. Oil level is not above full line on dipstick and does not smell much like gas but it's not great. I'm gonna change all the oil too to help protect them and give me a fresh Vaseline to monitor on the oil. I wish I was more knowledgeable on this stuff.
 
Thanks!!

If you want to, you could consider getting oil analyses done for both engines....nominal cost....haven't done it in a while - last time was like $20/per.
 
Guys...I took this picture of the starboard balancer at rest, I got lucky the timing mark stopped at the top. This is not where the engine is timed at idle, but for reference when trying to ascertain degrees, I submit this.
Remembering this is the counter rotating engine and that the balancer is turning counter clockwise, this is what I'm dealing with. As i previously noted, I can not pull the #1 plug to determine tdc due to being to hard to reach and up against a fuel tank. This timing tab is so pitted that marks are indiscernible. My internet research leads me to believe that on this particular tab, the furthermost counterclockwise peak is 0 degrees and each valley and peak is 2 degrees. If you would agree that my assumption of 0 degrees position is correct, then in this photo the timing mark is resting at about 8 degrees advanced. Does that jive with your interpretation. If so, my next step is to apply a timing tape to the balancer and read it again. with timing light set to 0 degrees.View attachment 16731
 
The long pole is the 'if' tied to where 0 (TDC) is on the tab....otherwise, what you offered is consistent....did you check the flywheel markings? its bulletproof as opposed to guessing....and once you verify where TDC is you don't have to bother again....
 
Like was said above two pistons are at TDC at the same time. That would be #1 and the fifth number in the firing order. If you use the piston stop be sure and disconnect the battery if you hit the starter the stop will punch a hole in the piston. There are some good videos on how to find true TDC then you will be able to get the timing confirmed.
 
It is always a good idea to get the timing right after you have changed distributors and you are getting some good advice on how to do that and it sounds like you are close if not there.

But is this really the root cause of your excessive fuel consumption on the starboard engine? I suppose it could be the cause if that engine is running so poorly that you have to advance the throttle on that side much more in order to match the engine rpm's. Do you have to do this? And if you do have to advance the starboard throttle much more, keep in mind that more likely causes of the mismatched throttle settings would be an ignition issue (bad plug wire, switched plug wires, cracked distributor cap, etc) or a mechanical issue (valve problem, usually a burnt valve). Both of those would cause a miss and give you unburned fuel in the exhaust and might lead you to assume the engine is running rich. Misses are very hard to hear on marine engines.

On the other hand, if the throttles are pretty closely matched at the same rpm's, then both engines are sucking the same amount of air but one is getting a lot more fuel. It must, in fact, be running rich. This is clearly a carburetor issue which can quickly be confirmed by switching them and seeing if the problem moves to the port engine.

Some thoughtful troubleshooting along these paths might be needed to identify your fuel issue.
 
Thanks to all of you who have been, and continue to help me thru this. Sharing an update here....I called the folks that I bought the distributors from, and they also are being very helpful. Spoke to their lead technician and he confirms I should be seeing about 28* when revved up to 2500-3000 rpms. He thinks I may have bad modules and has already offered to ship me new ones, no questions asked.
Yes, I do believe I also have a carb issue and I intend to tackle that next, or simultaneously. Both engines start up immediately with barely cranking. One local technician told me that this would indicate my timing is "damn close". Neither engine backfires, or sputters. They both sound really good at idle and at higher rpms. Both throttle positions are nearly the same with identical rpms. BUT......as I have stated before, the starboard exhaust smells a little gassy and leaves a trickle of a slick. I looked into the carb at idle with arrestor off, and observed fuel dripping from the primaries ("nozzles?) onto the closed throttle plates. These are Holley 750 cfm 0-0915-1 marine carbs. I tinkered with idle mixture screws to achieve maximum manifold pressure at idle and found that the port engine best was 1 1/4 turns out, but the starboard side found best at only 3/4 turn out. Who knows how long its been since these carbs were rebuilt, but with the symptoms I'm seeing, the starboard side is overdue. PLEASE keep he helpful advice and comments coming! This is one of the most helpful gatherings of fellow boaters I have encountered in my extensive boating life!
 
It is extremely critical that Marine Engine ignition advance be correct. A few degrees OFF during heavy engine loads can lead to Detonation and severe engine damage!

As Kim says, you may want to verify TDC by using a PPS (positive piston stop).
This will eliminate any concerns regarding the outer balancer ring having slipped on the inner hub.
After having verified this, be sure to punch-mark both the ring and hub (this will let you see if the ring slips in the future).

As Mark suggested, #6 cylinder comes around on the C/S exactly 360* after #1 has reached TDC C/S.
This means that you could use the PPS in the #6 spark plug port.

You would need a PPS tool, a degree wheel and some wire for a temporary and adjustable degree wheel pointer.
The wire will attach to a bolt (or ??) close by.

Some instructions will suggest splitting the degrees by 10 or so......
for more accuracy I will suggest using 30* +/- for your split!


Install the PPS and lock it so that it's depth does not change.
Gently bring the #6 piston in contact with the PPS tip.
Rotate the crankshaft in the opposite direction until once again the #6 piston contacts the PPS tip.
Move the pointer so that when the piston is stopped, the degree number that is being pointed to is equal in either stop direction.
This can be 27* or 31* or 25* or 33*....... (doesn't matter what number as long as they are equal when stopped)

Repeat this process until the pointer aims at an equal degree number during the "stop" in either direction!

Without allowing the degree wheel to slip against the harmonic balancer, remove the PPS.
Now rotate the crankshaft until the pointer is aiming at ZERO.
This will be your true TDC for that cylinder.

Now gently remove the degree wheel.
This is when you will either confirm that the OEM marks are correct........ or you will re-mark the balancer!


I would also suggest that you add marks (on the balancer ring) in increments of 5* up to 35*.
Doing so will allow you to use a standard strobe style timing light allowing you to view ignition advance in Real Degrees and in Real Time!


FYI:
Even though both distributors rotate CW, your RH Reverse rotation engine's Ignition Distributor will undergo a Downward force due to the opposite helical cut on the drive and driven gears.
(Std LH Rotation engine's distributor undergoes an Up-Lift force that is checked by the driven gear and housing contact)
Make sure that the RH Reverse rotation engine's distributor is correct for this application.

Here is your firing order that will show you where #6 is relative to #1.
Also an example showing an easy and accurate method to mark off the balancer for use when looking at the Progressive and Total Advance.
 

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The distributors have the same driven and will see the same thrust so they should be good to go as you go them.....
 
Mark, if the RH Rev Rotation engine’s camshaft is chain driven, it will rotate in the same direction as the crankshaft .

In order to continue rotating the oil pump and the distributor in the OEM direction, the drive gear and driven gear helical cut is opposite.
This creates an opposite direction thrust load.
 
I am in the process of changing one of my distributors (Delco EST). on the Standard rotation engine. They are small block Chevs (Crusader 270's)

Can I just aim the existing rotor at #1 Cyl to determine top dead center, remove the old distributor and locate the new one so it is aimed at the same point?
Or do I have to pull a valve cover and or use a tool?
Thanks for any advice.
 
I am in the process of changing one of my distributors (Delco EST). on the Standard rotation engine. They are small block Chevs (Crusader 270's)

Can I just aim the existing rotor at #1 Cyl to determine top dead center, remove the old distributor and locate the new one so it is aimed at the same point?
Or do I have to pull a valve cover and or use a tool?
Thanks for any advice.

Since I'm the guy who started this thread, I am obviously not the expert to rely on, but you should be able to drop in with rotor pointing at number one if engine undisturbed, then time it with light. My issue has been getting timing correct, or verifying it is not already there . Both my engines fired right up after doing as you plan.
 
..........................
The distributors have the same driven and will see the same thrust so they should be good to go as you go them.....
Mark, the only way that the two distributors can be the same would be IF the RH REV Rotation Engine's camshaft is twin gear driven.
Twin gears will rotate the camshaft in the conventional direction (same as a STD LH Rotation engine).
This would mean that the driven gear would not only be the same as the STD LH Rotation Engine's distributor driven gear, but it would also mean that the thrust is an "up-ward" thrust.
In this scenario, both distributors can be identical.

I am in the process of changing one of my distributors (Delco EST). on the Standard rotation engine. They are small block Chevs (Crusader 270's)

Can I just aim the existing rotor at #1 Cyl to determine top dead center, remove the old distributor and locate the new one so it is aimed at the same point?
First thing:
Bring the crankshaft around so that #1 cylinder is @ TDC on the C/S. Must be on C/S!!!!!
Remove the existing distributor.
Note that the rotor will rotate some while removing it.

Install the new distributor so that the rotor aims in the same (or in a similar) direction.
Gently lock the hold-down-clamp....... yet leave it loose enough so that the housing can be moved.

After connecting the power circuit and the spark plug cables in the correct sequence [18436572 (firing order) ] .... place a working spark plug into the boot of #1 spark plug cable.
Give the spark plug body good contact to the engine and position it where you can see the electrode.
With ignition key ON, rotate the housing in the CCW direction until you see one spark event.
Do this multiple times until you get a good feel for it..... and then STOP when you see the spark event.
Increase the tension on the lock-down bolt.
This will give you a starting point that will allow the engine to fire up.
Immediately set the BASE advance.




Since I'm the guy who started this thread, I am obviously not the expert to rely on, but you should be able to drop in with rotor pointing at number one if engine undisturbed,
Yes.... if you follow my above suggestion!

then time it with light. My issue has been getting timing correct, or verifying it is not already there . Both my engines fired right up after doing as you plan.
Setting ignition advance is only as good as the OEM timing marks are.
If in question...... use the PPS procedure to verify!

Keep in mind that BASE is BASE. We fire up on BASE and we idle on BASE...... that's it!
The more important aspect of Ignition Advance is the "progressive" advance and the "total" advance at the prescribed RPM.
In other words....... TA numbers are meaningless without an associated RPM!
 
Rick:

On the RH GM productions engines, I haven't seen anything other than a gear driven camshaft.....if you know of anybody that has produced marine engines, built on the standard production GM V-block, in the past fourty years, please identify the product(s).

I don't anybody that has rebuilt a (standard production) marine GM V-block RH engine that found reason to deviate from the factory approach.
 
Both mine turn clockwise. Both start right up. Total advance still me. Is total advance a sum of base idle timing added to advance at a given rpm? I.e...if you want to be total advance of 28* at 3000 rpm, is it just the timing reading when at 3000rpm, or is it like 20* advanced at 3000 rpm plus the 800 you set at idle with shunt. If it is NOT a sum of these two numbers, then why even bother with idle advance setting with shunt. I feel so stupid.
 
Here's another view:

An air fuel mixture takes a finite amount of time to burn. As an engine's RPM increases, the spark that sets the whole process in motion has to start earlier....hence the moniker timing advance.

total timing (degrees BTDC at a given RPM) = base timing (usually fixed) + timing adjustment available (varies with RPM)

Timing adjustment is usually done electronically (like you EST module does) or in the previous era, using weights and springs exploiting centrifugal force. The "how" isn't important - what is important is that the timing advances as designed...otherwise you will never see the rated output power developed...
 
For those of you who may have questions regarding my FYI comments in post #18:


quote_icon.png
Originally Posted by makomark
Rick:

On the RH GM productions engines, I haven't seen anything other than a gear driven camshaft..... if you know of anybody that has produced marine engines, built on the standard production GM V-block, in the past fourty years, please identify the product(s).
Mark, if that is the case, then there is NO concern. This is likely what the OP's RH REV Rotation BBC is using to drive the camshaft.
https://bpi.ebasicpower.com/shop/index.php?main_page=product_info&cPath=286_335_380 &products_id=10681&zenid=95f9a251cbcd98a58ada03f39 dd34e8d

However, in my post #18 I offering an FYI in the event that the OP's RH REV Rotation engine may have been using Chain/Sprockets to drive the camshaft.
If so, that would require a special RH REV Rotation ignition distributor due to the downward thrust force and the bearing surface that counters this thrust.
For example (using a SBC marine engine)..... the Mallory YLM624AV is for a Std LH SBC engine..... and the YLM624BV is for a chain driven camshaft for a RH REV rotation SBC engine.
Both rotate in the same CW direction.... both offer the same advance curve.... but, the BV driven gear thrust force is opposite.
See image below.

But like said..... if the OP's RH REV Rotation BBC Engine uses twin gears to drive the camshaft...... there is no concern. The driven gear will undergo an Up-Lift force just as with the STD LH Rotation system.


I don't anybody that has rebuilt a (standard production) marine GM V-block RH engine that found reason to deviate from the factory approach.
I am not suggesting that anyone deviate.
However, you must agree that we will (or have) see a RH REV Rotation BBC using chain/sprockets to drive the RH REV Rotation engine camshaft.





quote_icon.png
Originally Posted by realcaptron

Both mine turn clockwise.
Yes, this is due to the oil pump direction of which is driven by the distributor gear! There is no reverse direction oil pump.


Is total advance a sum of base idle timing added to advance at a given rpm? I.e...if you want to be total advance of 28* at 3000 rpm, is it just the timing reading when at 3000rpm, or is it like 20* advanced at 3000 rpm plus the 800 you set at idle with shunt.

I can easily sum this up for you.
Other than what an EST system will do with BASE advance, BASE advance is generally fixed. At the RPM at which the engine sees BASE advance, NO Progressive advance has begun.
Once RPM increases, so does the advance.
We call this "Progressive" advance.
As the RPM increases
further, the system eventually reaches what we call "Full In".
"Full In" means that the advance has reached it's limit at the prescribed RPM.
Since we do not typically operate our Marine Cruiser engines above 4k rpm, the "Full In" advance typically occurs between 3.2k and 3.7k RPM.


If it is NOT a sum of these two numbers, then why even bother with idle advance setting with shunt. I feel so stupid.
No need to feel stupid.
EST = Electronic Spark Timing. The EST ignition distributor is minus any mechanically advancing system.

Since we cannot create a spark event any sooner than it is initiated, the system delays a programmed and advanced spark event.
In order to establish where the distributor housing needs to be indexed, the shunt must be used for setting BASE advance.
Once out of BASE mode, the module then delays this event as per RPM.
All of this is accomplished via electronics.
So yes...... the Total Advance is the sum of BASE plus the progressive.
If you look at a ignition advance curve graph, it will typically be minus the BASE advance number in the left hand column.
See image below.





quote_icon.png
Originally Posted by makomark

Here's another view:

An air fuel mixture takes a finite amount of time to burn. As an engine's RPM increases, the spark that sets the whole process in motion has to start earlier....hence the moniker timing advance.
Yes... the fuel/air mixture undergoes a "Burn", not necessarily an explosion as we may think that it does.
As Mark says, the greater the RPM the greater the need for the ignition to occur earlier.
The ignition timing (via crankshaft angle) is designed to place the burn's maximum expansion at/near 12* to 14* ATDC .
This is referred to as LPCP .... or "location of peak cylinder pressure".
If LPCP occurs at 12* to 14* ATDC, it gives the power stroke it's maximum advantage over the crankshaft.
Baring that all else is correct, the spark event is given the last work regarding LPCP!


Mark's statement below is dead on.
what is important is that the timing advances is as designed... otherwise you will never see the rated output power developed...



 
My images did not post. Let's try that again.
 

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I received my new distributor and am about to start the change over. Reading through these threads I am now searching for the shunt wire to set the initial timing. Looking at my old distributor in the boat it looks like there is such a shunt in place. Question is why would it be hooked up ? or am I looking at something different here:
 

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It looks like it could be the timing shunt.....

Why is it plugged in????I'd suspect ignorance....with no first hand knowledge of the history of the boat, that's speculation only...
 
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