Electronic ignition conversion on OMC 5.7L

[tjsolberg]

I have a 1987 Sea Ray with OMC Chevy 350's and I just put in new Billet Pertronix Flame Thrower Electronic Distributors in my engines with new coils, plugs, and wires. Also put in a new ESA modules for the electronic distributors as well. My problem is when I go for a start to set the timing, the engine wants to start, but when I disengage the starter, the engine shutsdown. I connected two gray wires to the negative side of the coil and a purple/red and purple/black wire to the positive side of the coil from the engine harness, this is the same way it was hooked up with the old coil. I got the + and - distributor leads hooked up to the coil. This is obviously different than the old distributor because there was only the negative from the distributor. Do I need to connect the positive lead from the distributor to something else? It seems I'm losing the 12 volts for the distributor when I disengage the starter. Any help is much appreciated. Thanks.

Tim

 

[Black as]

Re: Electronic ignition conversion on OMC 5.7L

You need to contact Pertronix and they will help you on how to wire it up correctly to suit your engine

 

[drem312]

Re: Electronic ignition conversion on OMC 5.7L

what type of coil do you have is it the flame thrower or is it the standard type. the petronix set up likes 12 volts to it, the purple/red wire that comes from the back of the alternator is a resistor wire and doesnt have the power the petronix needs to operate.If you have the flame thrower petronix will tell you to run a wire from the ignition switch all the way to the pos side of your coil so that when the key is on the,, the positive side of the coil will have 12 volts.( remember not to leave key on when engine isnt running it could boil the coil) then red and black from the distributor to the red and black on the coil. The starter has one wire that runs to the coil + which is 12 volts when cranking this is why when you stop cranking it dies,system losing the 12 volts it needs to operate,,but call them give them your distributor number and set up they are a great help. if you have the standard coil most likely the red/purple will connect to them but the red wire off the distributor will need the 12 volts key on set up ,,but triple check bc things can fry

 

[tjsolberg]

Re: Electronic ignition conversion on OMC 5.7L

I emailed Pertronix and they responded just as you did.

"Did you bypass the factory resister? Your boat should have one for each engine and would explain the problem. They would bypass the resister during cranking so, then the distributor would get a full 12-volts. It would want to start but as soon as the starter disengages then it goes back through the resister and the distributor will shut down. I would suggest trying a hot wire directly off battery positive to the distributor positive. If the engine starts and runs correctly, then you would need to find and remove your factory resister"

I'm going to try the wire to the battery just to verify. If that works, then I'll just run a wire after the alternator and before the resister. I'm jus not sure where in the wire the resister is? Couldn't the wire itself be a resister wire? I'll find out tomorrow when I go down to the boat to work on it. Any more input, please let me know. Thanks everyone. I'll let you know how it goes.

 

[Black as]

Re: Electronic ignition conversion on OMC 5.7L

Try this link it may assist your problem

www.pertronix.com/support/tips/pdf/diodefix.pdf

 

[drem312]

Re: Electronic ignition conversion on OMC 5.7L

if you run the temp 12 volt wire like they said and it starts and runs after cranking it over then half the problem is solved but again what type of coil do you have? does it say 1.5 ohms or 3 ohms on side? is it a flame thrower? the flame thrower coils work hand and hand with the petronix conversion . but again the petronix needs 12 volts so if the coil you are using is a standard coil it will have less volts going into (via the red and purple resistor wire) and bc the the red wire coming off the dist is on top of the red/purple wire on the pos side of the coil it will not run ...so... confused yet? now if say you have standard coils that NEED the little juice input from the red/purple resistor wire you could still take the red wire off the dist and pull a 12 volt source when the key is on. This way the standard marine coil runs the engines ok, but not as good as the flame thrower and the petronix dist gets 12 volts that it needs to run make sense.You should get a wiring diagrham it will help. The 12 volt source from the key on position is easy to find.Remove or get to the underside of the ignition.With the key in the on position,not the cranking position,touch one of the prongs underneath with a meter ,or light to find out which one has the juice to it when the key is in this position then have someone turn the key off to see if the light goes out if so this is what you would use.If you have standard coils that need the resistor wire to it run a wire(14 gauge red wire) from this posistive prong to the red wire coming off the dist only.Hook the coils up the way you took them off if you have the flame thrower coils run this wire all the way back to the pos side of the coil then put the red from the dist on the pos side of the coil. There are other 12 volt key on sources in the engine compartment but that includes taking apart harnesses ,splicing etc.

 

[drem312]

Re: Electronic ignition conversion on OMC 5.7L

That link I believe is for older ESA"S if he got the newer style ones he should'nt need the diode fix to help with the shift assist

 

[tjsolberg]

Re: Electronic ignition conversion on OMC 5.7L

Well, here is the result; I connected the positive wire from the distributor directly to the alternator Excitation post bypasssing the resistor in the PU/RD wire all together (that is the same as splicing into the PU/RD prior to the resister). Fired right up, adjusted the timing, (by the way, what would be the optimum degree to set the timing?), verified the ESA worked, and everything seems to be spot on. The coil doesn't get a bit hot after running for about 30 minutes. Basically, all I did was installed the Pertronix distributors with Pertronix coils, installed new ESA's for the distributors, and just wired the positive lead from the distributor to the excitation post of the alternator and it works fine. I didn't do anything with the engine harness at all. The ESA is getting twelve volts, the distributors getting twelve volts, and the coil positive terminal is reading 10.5 volts when running. Anyone see a problem with this set up?

 

[drem312]

Re: Electronic ignition conversion on OMC 5.7L

good job..I think it will be fine you still have the original wire connected to the coils then? The initial timing could be 8 BTDC with the lower octane or 10 BTDC with the 89 and an idle speed in gear between 500-600 rpm and you should check timing on the water under load have you had it under load yet?

 

[tjsolberg]

Re: Electronic ignition conversion on OMC 5.7L

Thanks. Yes I still have the original wire in place. I didn't do anything with the original engine wire harness. Are those numbers correct? I had a marine mechanic tell me to run my engines at 3 or 5 BTDC with premium gas. I have always wondered about that because the book says what you said. I haven't had a load on it yet but will this weekend. Why is it better to set the timing on with a load on it?

 

[RogersJetboat454]

Re: Electronic ignition conversion on OMC 5.7L

The ESA is getting twelve volts, the distributors getting twelve volts, and the coil positive terminal is reading 10.5 volts when running. Anyone see a problem with this set up?

Most if not all electronically controlled ignitions do not have a ballast resistor. The ballast resistor was there to prevent the points from frying, and most conversion kits tell you to chuck or at least remove the resistor. I don't know what your wiring looks like now, but if you can remove the incoming feed from the ballast resistor and connect it directly to the coil, you should be golden.

 

[drem312]

Re: Electronic ignition conversion on OMC 5.7L

In my experience idling on muffs is different no back pressure thru the exhuast .You can intially set it on land then when its in the water you go to shift and the rpms are lower and it stalls. Your getting there !! I did my timing in the water and when you adjust by moving the distributor make very small movements it really makes a difference,,pinging is bad remember,A motor can run perfect on the muffs then when you have it on the lake and give it the gas it bogs and backfires.So I would set initail timimg between 8 or 10 and slowly come up on plane then if its running smooth give it the gas see what it does make small adjustments from there. If you are on the water and put it in neutral bring it up to around 2500 rpm and check timiing with a light it shouldnt be above 33 btdc on the balancer.I had a new reman jasper motor and the higher octane made a big difference in my boat

 

[bruceb58]

Re: Electronic ignition conversion on OMC 5.7L

You can do all adjustments in your driveway. No need to have it on the water. The distributor has no idea of load since it has no vacuum advance, just centrifugal weights that control advance. The timing at idle in neutral will be the same as idle in gear as the the distributor advance doesn't start until you hit 800 RPM. Initial timing should be 8 degrees. You can run it up to 3000 RPM on muffs to check total advance if you want. Just make sure you have sufficient water pressure/flow to do that.

At 3000 RPM you should have full advance. It will be 21 degrees in addition to your idle timing. If you start at 8 you will have a final value of 29. An advance type timing light makes it easy to check this.

 

[Rugbyman87]

Hi everybody, I'm new here and couldn't figure out how to make my own thread. ( I'm on my phone). I have a issue that has been driving me nuts for two days. I rebuilt my 350 over the winter, had it broken in and dynoed, with my distributor and carb. I dropped it on the boat last weekend and worked on getting it all hooked up this weekend. I had a napa hei conversion kit on it for two years and it has always worked great. But anyways. Went to start it and getting no spark. Got a new Mallory ignition kit because a wire arc'd during hookup and fried the little box inside the distributor. Replaced the ignition and nothing. Tried a brand new coil and nothing. The spark interrupter for the shifter was replaced last year. We are standing here scratching out heads now. We have tried unplugging shift interrupter and the alternator and hot wiring the coil and nothing. Any help or ideas would be much appreciated!!!

 

[Rugbyman87]

Should have added in its a 1979 sea ray with. 260 hp ( now a little more) Chevy.