Cobra hard to shift

[Tommywalton]

I just put my boat together and tested it yesterday. Its a omc cobra 1988 with 5.7 out of the lake it shifts ok. F-n-r once we rode for a bit it got very hard to shift. I tried triming it up and that helped a little. Any suggestions?

 

[bruceb58]

Re: Cobra hard to shift

You need to see if your ESA is operating properly.

Is your distributor still the stock one?

 

[Tommywalton]

Re: Cobra hard to shift

No, chunked points type. Large cap hei accel disrtibutor. Its a tight squeeze but it all fits. The linkage with the solenoids all looks fine. When cool it shifts fine. After an hour it wont hardly shift. Gear oil is at proper level and looks great. I dont think its in the gear box. The cable ends are mounted right by the exhaust riser. Could the heat be a problem? What is esa?

 

[bruceb58]

Re: Cobra hard to shift

Large cap hei accel disrtibutor.

That's your problem. The ESA works with a points type ditributor. The ESA is a module that is controlled by a microswitch where the lower shift cable gets operated by the cable coming from the shifter. It stumbles the engine as you shift so that you can get the drive out of gear. By switching to this distributor you knocked out this function and its a very necessary function. You have to have it working.

Is this a marine distributor? You have a picture of it or link to it?

If your new distributor looks like this

you need to remove it and put on a marine distributor.

 

[Tommywalton]

Re: Cobra hard to shift

Your post makes me think.. If the esa stumbles the engine to temporarily lower rpms i can see where this will help. If it is connected to the points distributor then the 12 v is also connected to my hei. Im using the same 12v source. I honestly cannot believe this is effecting the shifting right now. Both distributors are wired the exact same way. Also it shifts fine for a while. Perhaps the micro switch is going bad. It shifts hard with the engine running or not after a while. I auspect its the cable. I need more info on esa? Also does marine distributor have a provision for esa?

 

[bruceb58]

Re: Cobra hard to shift

So what distributor do you have?

The Delco Voyager EST marine distributor has an input for an interrupt switch. Basically, you would wire up the interrupt switch like the Mercruiser method to the distributor.

If your distributor is the one I show in the pic, there is no way to make an interrupt work with it. Put it on Ebay and buy the correct one. The advance curves are all wrong anyway and it also should NOT have a vacuum advance.

Curious how you wired up your 12V. You did bypass the ballast resistor right? Not that it matters since you need to get rid of it anyway.

Or you could put your points distributor back in there and it will work just fine. The ESA hooks up to the negative side of the coil. Curious what you did with that wire.

 

[SIMPLEARKANSAN]

Re: Cobra hard to shift

I just went through the exact issue with the same distributor. I bought the Delco est kit from Michigan Motors. Comes with everything with instructions on how to wire it up like a Mercruiser. You can toss the ESA with this set up.

 

[Tommywalton]

Re: Cobra hard to shift

Thanks guys. Heres the deal. I just checked the omc manual i have and it is wired just like the prestolite i had. The esa or electronic spark advance is still on the engine and hooked up. Probably doing nothing ad you guys have pointed out. I will say this that the engine is perfectly timed and it does have a vacuum advance. Seems too be working fine. Boat runs 48 mph with a 14"x19 prop. I would like to hook it up right and even get a small cap distributor just for more room. So the esa does exactlt what? The manual, seloc, says it is a electronic spark advancer and mentions nothing about the interuptor feature. I do see the interuptor switch on the schematic and have seen it on the engine also. Do all marine disrtibutors have the "interuptor" feature?

 

[Tommywalton]

Re: Cobra hard to shift

I just went through the exact issue with the same distributor. I bought the Delco est kit from Michigan Motors. Comes with everything with instructions on how to wire it up like a Mercruiser. You can toss the ESA with this set up.

Can you provide more info please?

 

[bruceb58]

Re: Cobra hard to shift

The ESA is not a spark advancer and if the Seloc says that, more proof that those manuals aren't worth the paper they are printed on.

Any engine that has a dog clutch like the OMC Cobra needs some way to interrupt the spark while shifting. On a mercruiser, the switch momentarily grounds the negative side of the coil, on yours, it does the same thing but pulses it electronically.

Here is a thread where DonS describes the wiring for the distributor
http://forums.iboats.com/showthread.php?t=287471
http://forums.iboats.com/showthread.php?t=489940

The vacuum advance is useless on a boat. You probably aren't getting full advance with your setup now so a true marine distributor will have the correct advance curve. The distributor you have now is also an explosion hazard.

 

[Tommywalton]

Re: Cobra hard to shift

The ESA is not a spark advancer and if the Seloc says that, more proof that those manuals aren't worth the paper they are printed on.

Any engine that has a dog clutch like the OMC Cobra needs some way to interrupt the spark while shifting. On a mercruiser, the switch momentarily grounds the negative side of the coil, on yours, it does the same thing but pulses it electronically.

Here is a thread where DonS describes the wiring for the distributor
http://forums.iboats.com/showthread.php?t=287471
http://forums.iboats.com/showthread.php?t=489940

The vacuum advance is useless on a boat. You probably aren't getting full advance with your setup now so a true marine distributor will have the correct advance curve. The distributor you have now is also an explosion hazard.

Thanks for the info, another expensive lesson. The hei is out and i put the prestolite back in. I timed it and it won't run when wired the correct way. It has a petronix kit instAlled by previous owner. When the positive and neg are hooked to the coil like the wiring diagram shows it will fire for a sPlit second but not run. When i run the pos distributor wire to a 12v source(battery) it runs great. While running in shifted it and noticed no change in engine. I moved micro switches and nothing. Oh btw thanks for the exPlosion hazard warning. I have a 4 and 6 yr old. I had no freaking idea!

 

[bruceb58]

Re: Cobra hard to shift

The Pertronix kit will also cause the ESA not to work unless you out in the "diode" fix that you can find on the pertronix website.
http://www.pertronix.com/support/tips/pdf/diodefix.pdf

The reason it runs for a split second is that when you crank the starter, full voltage is supplied to the coil by the starter solenoid. When you are not cranking, voltage is supplied by the ballast resistor. Somehow, the ballast resistor was removed from the circuit at some point. You should have 2 wires in the positive side of the coil. The pertronix needs to get its voltage from before the ballast resistor.

 

[Tommywalton]

Re: Cobra hard to shift

Bruce you deserve a piece of cake! No way its that simple?! This is great man thanks! I am about frustrated with this basket case. I bought a hei distributor, created a freaking time bomb all because i only need 2 diodes and a couple resistors? Ha the lessons learned. One day i might accept the fact that boats and car engines share blocks, heads and cranks and thats about it. Thanks again

 

[bruceb58]

Re: Cobra hard to shift

http://www.pertronix.com/support/manuals/pdf/ignitor12vneg.pdf

This is how you need to wire it. You still need your ballast resistor so don't run it with full voltage at the coil or you will burn it up.

Also, shifting it in your driveway on muffs should not cause the ESA to stumble the engine. It requires the force of the water shifting out of gear for the ESA to activate. You can test the ESA by depressing the microswitch though.

 

[Tommywalton]

Re: Cobra hard to shift

I just picked up the stuff required from radio shack. I should wire this exactly like the diagram and all should be well? It basically looks like the diodes and resistors wire between the two existing grey wires on neg side of coil to me. All the original wiring is intact with no issues. However i honestly dont know where the ballast resistor is. I havent seen it but also havent looked. The only thing changed waa the two wire ends going to the coil. Where is the ballast. I would like to check all of this before running. Also i checked the micro switches last night while running and no change in sound at all. Im sure its because i had to give the distributor 12v source to keep it running. I hope i didnt burn up anything. Alsoy diagram in seloc has 1 mistake i found. The starter connections are wrong in diagram

 

[Tommywalton]

Re: Cobra hard to shift

Also ive read a previous post you replied to. I think what i need to do is supply the pertronix conversion with switched 12v, hook up original pu/red wire to coil from altenater with the resistor(around 9v) then wire up the resistors and diodes like the diagram. Both are grey and specific so i will trace them. Does this all sound right?

 

[bruceb58]

Re: Cobra hard to shift

The ESA doesn't care what voltage the coil is running on. Could also be that the ESA is bad but not likely. There is an ESA available that doesn't require the diode fix. It also doesn't require the second switch which is called the overstroke switch. Just for your info, make sure you are not pushing on the overstroke switch when doing your test. Also, if the overstroke switch is operated, it will disable the shift interrupt switch. That clear?

The ballast could easily be a wire. I don't remember what OMC used. Easiest way to see is to ground the ground side of the coil with a test wire and verify the voltage on the positive side drops to 9V or so.

 

[skidooseadoo83]

Re: Cobra hard to shift

Heres another simplified diagram of the diode fix from pertronix.

 

[jarrod1995]

Re: Cobra hard to shift

Heres another simplified diagram of the diode fix from pertronix.
View attachment 139837

I have tried this and its still not working either, there were two gray wires on mine. I put it between the one that runs to the ESA. The other one disappered into a bundle. Pulling up to a dock is rough though. FWD is a beast and sometimes just wont go.

 

[bruceb58]

Re: Cobra hard to shift

I have tried this and its still not working either, there were two gray wires on mine. I put it between the one that runs to the ESA. The other one disappered into a bundle. Pulling up to a dock is rough though. FWD is a beast and sometimes just wont go.

You have a Pertronix module right?

You have the diodes with polariity in the correct direction?

Have you tested the operation of the ESA manually by just operating the shift switch?

By the way, you should start a new thread with your question. You will get more responses that way.