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Delco Est timing issue

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Jeremiah1103

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I have a 1986 crusader 454 right hand rotation if I sent my base timing for 10 degrees with the timing shunt then disconnected and restart engine my timing jumps up to 20 degrees and my total advance is only 28 degrees. I'm lost on why my distributor keeps jumping 10 degrees when I take the timing shunt out. If someone could please point me in the right direction
 
RH Reverse or LH Standard........ the ignition distributor doesn't know the difference. :D

I'm thinking that during cranking/starting rpm, the system should throw at/near only 8 to 10 degrees at it.
When the shunt is removed, it may be common to see more spark lead.... but I'd question 20 degrees!
Hopefully Mark will chime in...... he's more up to speed on this than I am.

Here is a similar ME.com thread.
http://www.marineengine.com/boat-fo...g-Advance-Curve-Map-Delco-Remy-HEI-EST-LH-350


The more important aspect will be the Progressive spark lead and the TA (total advance).

Keep in mind that TA numbers are rather meaningless unless associated with an RPM. In other words....... at what RPM are you seeing 28*?

I'll suggest that you find your OEM ignition advance curve graph and reference it when setting/checking ignition advance.

The curve should look similar to this:
(example ONLY...... use your OEM curve graph!)
 

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I would say probably around 2800 to 3000 I have the total advance of the distributor. I've had it up to 4000 rpm and it stay the same. I've read all kinds of articles trying to figure out what would cause the module to advanced to 20 degrees when I've set the base at 10 degrees. I've even tried to set base to 0 to get 10 degees without shunt then only advance to 18. No hard start or anything when idle is at 20 degrees it's just doesn't like the rpm's below 750 or it shalls out
 
I measured the wires going to the coil this morning. I have 12.6 volts with key on and 13.7 with the engine running. I'm guessing the yellow wire from the alternator is causing this. Could this be the cause of my timing spike? Is 13.7 volts to high?
 
.........................
Keep in mind that TA numbers are rather meaningless unless associated with an RPM. In other words....... at what RPM are you seeing 28*?
Click to expand...
Jeremiah1103 said:
I would say probably around 2800 to 3000
28* TA @ 2,800 to 3,000 RPM may be a tad bit early. I would be more comfortable if the TA held off until around 3,200 RPM.


I have the total advance of the distributor.
Just to be clear and FWIW/FYI...... there is no mechanical advancing within the EST distributor.
When BASE/Initial is set, the actual spark event triggering is at/near Full Advance.
The module then delays the final spark as per engine RPM.
(i.e., more delay at low rpm........ and progressively less delay at the higher rpm)


I've had it up to 4000 rpm and it stay the same.
Yes..... most ignition systems offer what we refer to as being "Full In" by 3,500 rpm or so.

I've read all kinds of articles trying to figure out what would cause the module to advanced to 20 degrees when I've set the base at 10 degrees. I've even tried to set base to 0 to get 10 degees without shunt then only advance to 18. No hard start or anything when idle is at 20 degrees it's just doesn't like the rpm's below 750 or it stalls out
If it fires up and idles OK @ 20* BTDC, there is no real issue.
However, not idling at/below 750 rpm is an issue!

Sorry....... I wish that I could be of more help!
Click to expand...
 
Jeremiah1103 said:
I measured the wires going to the coil this morning. I have 12.6 volts with key on and 13.7 with the engine running. I'm guessing the yellow wire from the alternator is causing this. Could this be the cause of my timing spike? Is 13.7 volts to high?
Click to expand...

You should have the same voltage at the alternator, coil and at the battery when the engine is running.

anything hooked up to the charging circuit should show the same voltage with minimal voltage drop.

Timing Chart.

Untitled.jpg
 
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OK I next chance I get I'll will go shoot the timing again and get a better curve. I have seen other post that say don't worry about the base timing being high, but I just wanted to be sure that there is something wrong and I end up tearing the motor up. The only time it doesn't want to idle at lower rpms is when you run it for awhile. I guess that's most likely the carb. I bought the boat from a guy that didn't use the boat much. Just wasn't sure if there was something else to check for?
 
So here is my timing curve I got this evening
Rpm. Degrees
700- 20
1000- 22
1500- 24
2000- 25
2500- 25
3000- 27
3500- 27
3800- 28

How does that look or should I try to get the 30 degrees at full advance
 
2X what Chris said.....and check to see if the module is a Delco one....some of the aftermarket ones don't behave very well. Unless you have a ECU added, the module will add timing based on the RPM it senses....and the rpm where the advancing starts will vary a bit.....going on memory, it starts nominally around 700 rpm. And make sure you have a good timing light, especially if using the 'electronic advance' version.
 
I checked the module is there anyway special to look for to tell the difference in a delco or some aftermarket module they slapped in this kit I bought
 
The one i have in my box has GM cast into the plastic ''cover" on the top....

Also, I checked my shop books for notes and what you have seen is not unusual....the advance function will start 'early' (300 rpm) in a bare EST setup compared to a mechanical advance system....so, like Chris suggested earlier, the easiest way to get it 'right' is to set the timing at full advance and don't worry about what it is at idle....
 
I set the 30 degrees at 4000 rpms and idle was at 650 rpms showed 25 degrees now. The module I have must not be a GM module cause it doesn't show any of those numbers listed I bought the kit from marine Depot and now I see they sell a module for carb engine. Maybe this has something to do with it. Maybe I'll look into getting a true GM module.
 
I have had exactly the same problem with my new EST Delco - this is a very poor product. I could only get 10 degrees advance out of the Delco EST Module and this kicked in at 2800rpm in one single jump! That's right, no curve at all. Suggest setting the total advance as required, mine runs ok but nothing compared to the old Thunderbolt IV.

The module also runs very hot, probably from heat induction through the aluminium distributor shaft which can't be a good thing so check this. Also check you have a good earth.

In hindsight I should have purchased a new Mercruiser Ignition Module for a little more and had a perfect curve - original is far superior in my view.

If you find a way for of working a curve out of a Delco please let me know.
 
makomark said:
................. And make sure you have a good timing light, especially if using the 'electronic advance' version.
Click to expand...

+ 1 !

No cheap Harbor Freight units!

Or..... mark off the harmonic balancer up to approx 35 degrees BTDC, and use a standard strobe light so that you can view the advance in Real Time/Real Degrees!



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