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Mercruiser 5,7 with Delco EST don't save the distributor timing

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yearone

New member
Hello
I have a Delco EST distributor on my mercruiser 5.7.
I have changed ignition module, pick-up coil and ignition coil. Also distributor cover and rotor. When I start up the engine it is at 20-25 degrees of ignition so I plug in the jumper and put + 12v on the black cable and hear how the engine calms down. I adjust the ignition to 10 degrees but as soon as I switch off + 12v it jumps back and settles at 20-25 degrees.
I have also tried turning off the engine and switching this off and starting, no difference.


Has anyone experienced this? What am I doing wrong?
 
What you are seeing is pretty typical for a stand alone EST system....

What's more important is to ensure the MAX advance is correct and you can check that without the jumper....
 
Docksidemarineservices said:
How is the boat engine running? Is it making full power?
Click to expand...

I have not tried to drive it with the new ignition module. But the engine is runing very well att neutral shift
I switched because the ignition on the old module never reached above 15 degrees. and was los of power
Mounted the new parts and tried to set the idle at 10 degrees to see what total advance reached
 
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makomark said:
What you are seeing is pretty typical for a stand alone EST system....

What's more important is to ensure the MAX advance is correct and you can check that without the jumper....
Click to expand...

I think 20-25 degrees is very high at idle, at 3000 rpm I reach about 30 degrees but I think it is strange that in that case it only works with 5 degrees
 
I'm not disagreeing with you.....they behave closer to 'normal' when connected with a MEFI controller.....
 
yearone said:
...I plug in the jumper and put + 12v on the black cable and hear how the engine calms down. I adjust the ignition to 10 degrees but as soon as I switch off + 12v it jumps back and settles at 20-25 degrees.
I have also tried turning off the engine and switching this off and starting, no difference.
Click to expand...

Going back to the beginning, with the jumper installed and powered and the timing adjusted, have you tried just pulling out the jumper (with power and without power) before shutting off the engine? I think it's the removal of the jumper that locks in your timing adjustment.
 
If you set the timing correctly with the jumper and base idle is correct you should see total timing in the 32-34 degree range around 3000 rpm.

Go run the boat on the water.
 
Docksidemarineservices said:
If you set the timing correctly with the jumper and base idle is correct you should see total timing in the 32-34 degree range around 3000 rpm.

Go run the boat on the water.
Click to expand...

The problem is that the ignition module does not remember the setting of 10 degrees. If I remove + 12v it goes back at 20-25 degrees at idle. The same thing if I pull out the entire connector, tested with motor both on and off before removing the basic adjustment bracket. Can anything else on the engine affect this?
 
DJR said:
Going back to the beginning, with the jumper installed and powered and the timing adjusted, have you tried just pulling out the jumper (with power and without power) before shutting off the engine? I think it's the removal of the jumper that locks in your timing adjustment.
Click to expand...

I have tested both. And followed the Delco manual very carefully. Can anything else in the engine affect this?
 
yearone said:
The problem is that the ignition module does not remember the setting of 10 degrees. If I remove + 12v it goes back at 20-25 degrees at idle. The same thing if I pull out the entire connector, tested with motor both on and off before removing the basic adjustment bracket. Can anything else on the engine affect this?
Click to expand...

If you hook up the jumper and set the timing and remove the jumper, then hook the jumper back up is the timing still where you set it? YES, then run the boat.

The only timing you can read with out the jumper is total advance.



Just because you don't understand how the system works does not mean there is a problem with it.
 
Docksidemarineservices said:
If you hook up the jumper and set the timing and remove the jumper, then hook the jumper back up is the timing still where you set it? YES, then run the boat.

The only timing you can read with out the jumper is total advance.



Just because you don't understand how the system works does not mean there is a problem with it.
Click to expand...

Hello
Thanks for the help, then I understand how it should be. I thought the ignition would remain around 10 degrees even when removing the jumper.
I removed the jumper and went on a test drive and it worked very well.
The marina here where I bought the parts had no good answers to what I was wondering about so I was confused :)


as parentheses to the last thing you throw out of you I have never stated that it is wrong with the system but rather what I do wrong :) Have a good weekend and again a big thank to you
 
The EST 'module' has it's timing advance curve built into the module. (when used with a MEFI controller, the controller provides timing control.) The 'jumper' locks the internal curve to its NO advance value so you can set the initial timing. Removing or disconnecting the jumper enables the internal advance function.

The internal advance curve is rather steep....it is common to see 20-22 degree of timing at 1000 RPM on a V-8, maybe more with aftermarket modules. Max advance is usually seen at 2500 RPM.
 
Perhaps this may help some of us who may not fully understand the EST and ignition advance/timing!


EST = Electronic Spark Timing.
There is NO mechanical advancing mechanism within the ignition distributor.
There is also NO actual or physical spark advancing done by the module.... but read on before disagreeing!


**Since the laws of physics do not allow a remote electrical event to occur any sooner/earlier than when it was initiated, the EST system must incorporate a delay of an advanced spark event via the module's electronics.

So..... the EST distributor's triggering event must produce the spark event at the total advance value. In other words, if the distributor was indexed for a working module, and if we were to take the module out of the equation, the triggering system would send out Full Advance, or very close to it, no matter what the RPM.

Going back to ** above:

The EST module creates a delay of the spark event.
The EST module's delay is greater at lower engine speeds, and the delay is less as engine RPM increase.
If the engine must see a BASE advance of 8* to 10*, then the system's delay is at it's greatest value at low idle RPM.

The controller is progressively delaying a range of let's say 0* to 22* (32* TA minus a BASE of 10* = 22*).
In other words, if the engine requires a BASE advance of 10*, the controller is delaying at it's MAX of 22*.
If the engine requires a TA of 32* at the Full In RPM, then the controller is now delaying at it's minimum or zero.




Now the SBC Marine version:

The common SBC Marine engine is fitted with the non-ideal GM Full Dished pistons, of which makes this engine more prone to Marine Load/Ignition Induced Detonation.

The EST (and any other Marine ignition systems) are designed and adjusted to hold back the advance in order to avoid detonation.

The internal advance curve is rather steep....
1..... it is common to see 20-22 degree of timing at 1000 RPM on a V-8, maybe more with aftermarket modules.
2.... Max advance is usually seen at 2500 RPM.
Click to expand...

1.... It's been my experience that BASE advance should be in the range of 8* to 10* BTDC......... much more, and starting becomes an issue. Once started up, it will handle a greater BASE value, and we will see an increase in RPM, but at 20*-22* it will "buck" during starting, and may not even start!

2.... Most SBC Marine engines want to see a Full In advance of approx 28* to 30* and no earlier than at/above 3,200 RPM.
Any sooner or any greater, puts the engine at risk of detonation damage.

If the advance curve continues beyond 3,200 RPM, and remains linear, it is typically a non-issue.


I know that many shops set BASE advance, and do not look any further. I have never sent an engine away without having looked at both the progressive and the TA. In most cases all is ok.... but occasionally we will find one that is not correct!


Always refer to the OEM ignition advance curve for your engine model and serial number.
It would be a good idea to see if the system is actually delivering it.





.
 
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