Hard plane after switch from points ignition

[ROY WILLIAMS]

Today I swapped out the module for an Ac Delco module. Now I get 15⁰ total timing. 10⁰ base plus 5⁰ advance. At this point I am at a complete loss. Getting ready to ditch the sierra EST and find something different.

The 650-800 rpm engine 1985 the timing 4-8 BTDC ....now the rpm 1500rpm timing ?
...

my engine oil 30wt and the zinc plus 4-6 OZ ...the gasoline 90-93 octane , the timing 4 BTDC ..
my 1978 MCM470 is a very great engine ! gasoline 93 octane ...the 40 years

 

[kbreks]

The 650-800 rpm engine 1985 the timing 4-8 BTDC ....now the rpm 1500rpm timing ?
...

my engine oil 30wt and the zinc plus 4-6 OZ ...the gasoline 90-93 octane , the timing 4 BTDC ..
my 1978 MCM470 is a very great engine ! gasoline 93 octane ...the 40 years

Im not sure what the timing is at 1500 rpm. But at 2400+. Its 18⁰. 10⁰+ 8⁰ advance. I think my issue is that its not going into base timing mode. So when i set my initial timing, im already advanced half way into the curve.

 

[jimmbo]

Do you know what the Original Distributor had for an Advance Curve? You should be able to get that info from a Factory Manual

 

[Scott06]

Im not sure what the timing is at 1500 rpm. But at 2400+. Its 18⁰. 10⁰+ 8⁰ advance. I think my issue is that its not going into base timing mode. So when i set my initial timing, im already advanced half way into the curve.

If you can’t get it into base just set the total timing at 2800 rpm or so. not sure what total timing specs are for your engine . Later 4.3 s took I think 24 degrees total so set it around there and see how it runs

 

[alldodge]

Im not sure what the timing is at 1500 rpm. But at 2400+. Its 18⁰. 10⁰+ 8⁰ advance. I think my issue is that its not going into base timing mode. So when i set my initial timing, im already advanced half way into the curve.

This is most likely the issue
You had points so the shift interrupter connected a ground to the coil to make the motor stumble. EST needs 12V at the interrupter to do the same thing

So you need to remove the ground and connect 12V to switch

 

[Lou C]

Not sure what Merc’s spec was for this engine but the OMC version with the Prestolite points distributor was set to 6* BTDC and got 12* of centrifugal advance for a total of 18*. Why they were set up to get less advance than any of the V8s I don’t know but that’s how it was. Engine runs fine easily pulls 4600 rpm.

 

[Lou C]

PS I know Merc used the same Prestolite distributor as OMC because I have a spare one; the OMC one is painted grey and Merc is painted black. Otherwise the same

 

[kbreks]

This is most likely the issue
You had points so the shift interrupter connected a ground to the coil to make the motor stumble. EST needs 12V at the interrupter to do the same thing

So you need to remove the ground and connect 12V to switch
View attachment 399334

I have changed the interupt to 12v (which is disconnected entirely during setup). My total advance from factory is 14⁰ advance above base. As suggested above i am going to give it a shot at setting total timing as i think the module wont go into base timing mode. According to the service manual i should be all in 22⁰. (14⁰ + 8⁰ base). By 2400 rpm. So i will set it to that and see what happens from there. Hopefully no engine damage.

 

[Scott06]

I have changed the interupt to 12v (which is disconnected entirely during setup). My total advance from factory is 14⁰ advance above base. As suggested above i am going to give it a shot at setting total timing as i think the module wont go into base timing mode. According to the service manual i should be all in 22⁰. (14⁰ + 8⁰ base). By 2400 rpm. So i will set it to that and see what happens from there. Hopefully no engine damage.

Cannot be worse than a blown up engine ....

seriously if you set it how you outline above you will be ok as you are setting to factory spec.

 

[kbreks]

Set total timing. water tested the boat. distributor is actually taking timing out at 1500rpm. get full timing at 2500rpm and anything above it takes timing out again. time time to ditch the delco est and go back to points if i can get my points distributor rebuilt.

 

[jimmbo]

Set total timing. water tested the boat. distributor is actually taking timing out at 1500rpm. get full timing at 2500rpm and anything above it takes timing out again.

I'm gonna need a Decoder Ring to figure what is being said. What do you mean "taking/takes Timing out"?

 

[alldodge]

Set total timing. water tested the boat. distributor is actually taking timing out at 1500rpm. get full timing at 2500rpm and anything above it takes timing out again. time time to ditch the delco est and go back to points if i can get my points distributor rebuilt.

Try this first
Get boat in open water, disconnect one side of the shift interrupter switch. Run it and see if it does as it should.

It could be as the throttle is moved forward the interrupter switch is some how engaging

Probably need to shut motor off to get back into neutral

 

[Lou C]

Set total timing. water tested the boat. distributor is actually taking timing out at 1500rpm. get full timing at 2500rpm and anything above it takes timing out again. time time to ditch the delco est and go back to points if i can get my points distributor rebuilt.

timing out meaning that it goes back to zero advance?
then what alldodge says makes sense....shift interrupt
I had the switches stick on (OMC) and it wouldn't run above idle....the OMC system doesn't short the ignition momentarily but it lowers the idle to 450 rpm instead, this way if you took a little too long in shifting the engine doesn't stall (if in good tune that is).....
replaced switches and ESA module and was back in business
what was wrong with your points distributor?
I prefer points, simple, springs and flyweights, a little maintenance instead of electronic mystery boxes.

 

[kbreks]

By taking timing out i mean it goes from 14⁰ to 9⁰ advance. Then at higher rpm goes from 22-24⁰ to 18⁰. I did try removing the shift interupt switch and it didnt seem to change anything. My points distributor springs are shot so after i come off plane it stays advanced and will not do channel speeds.

 

[Lou C]

Any old school hot rod shops near you?
Maybe with a Sun distributor machine?
They prob could replace the springs so your advance rate is correct

 

[kbreks]

Any old school hot rod shops near you?
Maybe with a Sun distributor machine?
They prob could replace the springs so your advance rate is correct

Little did i know there is actually a shop about 5 minutes away from me that used to hot rod boats. They are going to have a look at my distributor.

 

[cyclops222]

Those timing numbers are terrible.
Put the original distributor & advance system back in the engine.

 

[kbreks]

Those timing numbers are terrible.
Put the original distributor & advance system back in the engine.

Thats what im doing. But i need the original one rebuilt. Manufacturer doesnt want to take the delco EST distributor back. Which is awesome

 

[Scott06]

Thats what im doing. But i need the original one rebuilt. Manufacturer doesnt want to take the delco EST distributor back. Which is awesome

Is this a true Delco eat or one of the aftermarket knock offs? If u paid with a card dispute the charge they should understand that something is wrong timing wise

 

[kbreks]

Is this a true Delco eat or one of the aftermarket knock offs? If u paid with a card dispute the charge they should understand that something is wrong timing wise

Unfortunately it's a sierra. Which i didn't realize there was a difference between sierra and Delco. Paid cash. Purchased it from someone i know so i should be able to get it refunded eventually. They just want me to keep trying modules but I'm not interested in that after seeing others having the same issues all over other forums.