Completed OMC 3.0 Points to Delco EST Conversion

[TwoBallScrewBall]

Well, a nice iboats member sold me a delco EST ignition he opted not to use. Something failed in my points ignition a few weeks ago (don't know what exactly because I jsut replaced everything all at once to fix it) and resulted in me getting towed in at 2:00am, so I really wanted an electronic conversion. I was going to go with the pertronix, but then this opportunity came up and I jumped on it. <br /><br />I got the EST installed and working today. I started working on it yesterday, but a bad thunderstorm dumped on me before I could finish the job so I finished it today. Seems to run very well on the trailer, going to take it for a test run tomorrow if the weather holds. I noticed a couple things. <br /><br />For one, with the points and mechanical advance on the old distributor, when setting the timing it would bounce around a degree or two each way, with the EST installed the timing mark is rock solid, the timing light blinked at exactly 0 degrees every time. <br /><br />Also, the idle is definitely much smoother (RPM much more steady) and it seems to start quicker, the starter barely turns over and it’s running. I haven't re-gapped my plugs yet, they're still at .035, need to open them up to .045. Didn’t run into any problems with the wiring, just followed the diagram I had for a V8 EST engine, same wires just 4 more sparkplugs! <br /><br />The shift interrupt seems to work fine too, the OMC ESA module is completely bypassed and I’m now just running +12v through the interrupt switch, which gets fed to the timing shunt when the switch trips and seems to idle down the engine well. This was how the diagram (a merc diagram) showed it to work, and it seems to be working. <br /><br />Just a couple things that I wondered about...<br /><br />For one, other than the resistor wire which only had 11.7 volts, I could not find another switched ignition wire with a full +12V at the engine. I read the ESA needs the full voltage so what I did was wire up a relay. The resistor wire turns on the relay and the relay passes straight +12V from one of the starter solenoid posts to the distributor/coil. <br /><br />Also, the merc diagram shows that the two white wires on the timing shunt should not be jumped except when setting timing. If I remove the jumper and hit the shift interrupt the engine just dies, no stumbling, just dies like if you turned it off. If I leave them jumped and hit the shift interrupt the engine idles down like I think it should. Anyone know for sure how this should be wired up? Jumped or not?<br /><br />Other than that it's working perfect, can't wait to try it out on the water tomorrow.

 

[TwoBallScrewBall]

Re: Completed OMC 3.0 Points to Delco EST Conversion

bump, can anyone confirm whether the jumper wire on the distributor stays on or not?

 

[affa]

Re: Completed OMC 3.0 Points to Delco EST Conversion

Hi Steve<br />Im into the same thing, Ive only read about how to do it since Ive not get the shunt yet.<br />What Ive read is that the jumper wire should be disconnected, and you should see the timing advance about 10dg after you disconnect it.<br />The way youve done it sounds like what Ive read, the only thing I can think off is if the wires to the shift-interupter get mixed up then maybe it doesnt give 12v back to the distributor, which its supposed to when you shift.<br />Regards<br />Affa

 

[TwoBallScrewBall]

Re: Completed OMC 3.0 Points to Delco EST Conversion

Definitely getting +12V to the interrupt and then on to the distributor shunt. Checked with a voltmeter. <br /><br />The timing portion worked exactly as expected, no problems timing the engine and when I removed the +12v from the shunt the timing advanced as expected. I actually just tripped the interrupt switch by hand to set the base timing so I know that works. With the old ESA, the engine would run very rough but still stumble along when triggered. Now, If I remove the jumper and hit the shunt with +12v through the interrupt it just dies. With the jumper in place it idles down from about 600rpm to about 400 or so. I'm going to try it both ways once on the water and just see which way works (shifts without stalling) better.

 

[TwoBallScrewBall]

Re: Completed OMC 3.0 Points to Delco EST Conversion

Ran it today. Runs soooooooooooo good. I can idle along up the creek at like 0.5mph and the enigne is perfectly smooth. <br /><br />As for the jumper wire, the boat shifts effortlessly with the jumper there, and also shifts effortlessly with the jumper removed, but with the jumper removed if you shift slowly it dies. Does not die with the jumper there, no matter how slow you shift. For me, I know it wouldn't be a problem, but when I let the wife or friends drive I know they'll be killing the motor. I'm leaving the jumper there.

 

[akriverrat]

Re: Completed OMC 3.0 Points to Delco EST Conversion

better check that the timing actually advances with the jumper connected.

 

[TwoBallScrewBall]

Re: Completed OMC 3.0 Points to Delco EST Conversion

It does, as long as the +12 is removed from other lead. I checked. Out on the water three times now and I haven't been happier with it since i got it. It's a whole new boat the way it's shifting and running.