88 OMC 5.7 cobra shift question

[Don S]

Re: 88 OMC 5.7 cobra shift question

It isn't supposed to activate when going into gear. Only when coming out of gear under load.

 

[wellcraft 185]

Re: 88 OMC 5.7 cobra shift question

Oh.. With that in mind I am barking up the wrong tree!.<br />I will take to lake next weekend and studdy it in "real time" and report.<br />Thanks Don and all who took the time to help.<br /><br />ps. Does it just then "clunk" into gear at factory idle rpms with no shift assist at all?.

 

[Don S]

Re: 88 OMC 5.7 cobra shift question

Yes, it just clunks into gear. It's a dog type clutch in the drive, that is exactly what it's supposed to do.

 

[waterone1@aol.com]

Re: 88 OMC 5.7 cobra shift question

Just thought I would add something that came to mind. As Far As I remember, the cutout switch will, in normal situations only be activated for a split second (unless you have bad cables or drive problems). If, during testing in the driveway you hold the switch in....it should kill the motor. As Don said, it shouldn't even activate if the prop is not in the water.

 

[Don S]

Re: 88 OMC 5.7 cobra shift question

It should NOT be activated at all when going into gear, only when coming out of gear when the boat is IN the water with a normal prop load when in gear.

 

[Don S]

Re: 88 OMC 5.7 cobra shift question

As I recall, haven't done this for a while, there is something that has to be done to the overstroke switch to make it work with the Merc system but don't remember what it is exactly. Anyone out there remember?

 

[rodbolt]

Re: 88 OMC 5.7 cobra shift question

DonS<br /> yeo have to rewire the connector plug. I justdid this on an abortion. I did not install the package but they brought it to me when they could not make it run. seems a dealership sold a PCM 5.7 complete as a replacement for a 93 5.7. the PCM motor has a delco EST and the old OMC had a prestolite with an ESA. the way the new iring works is blue to the cutout switch and out of the cut out switch to the overstroke and out of the overstroke to the ign circuit.<br /> it can also be wired to open the circuit depending on what ign system is used.<br /> for captnemo's benifit.<br /> the cut out sometimes will remain ON when in gear and moving the throttle. the overstroke switch opens the circuit to allow normal ign operation. however when the shift linkage moves again towards the nutral position the overstroke cams have to be adjusted so the switch closes and allows the still closed shift interuppt switch to do its thing. not all OMC's hadan overstroke but one can be added. its not rocket science but it does require an understanding of why its there, how it works and what happens if it does not.

 

[Don S]

Re: 88 OMC 5.7 cobra shift question

Here is a quick drawing on how I think the wires should be hooked up to your TB4 distributor.<br /><br />

 

[rodbolt]

Re: 88 OMC 5.7 cobra shift question

looks good <br /> you may wish to higlight the b-c jumper.<br /> I hate rigging and digging but sometimes ya gotta do what ya gotta do . <br /> Captnemo. with this arrangement the ESA module is removed from the engine. makes more room <br />it will not however take the place of proper cable adjustments and stuck or sticking cables and bellcranks.

 

[tommays]

Re: 88 OMC 5.7 cobra shift question

capt nemo <br /><br />very nice looking i was hopeing it would not look like this<br /><br />

<br /><br /><br />tommays

 

[Don S]

Re: 88 OMC 5.7 cobra shift question

Suppose I just over complicated it?<br />How's this.<br /><br />

 

[newport dave]

Re: 88 OMC 5.7 cobra shift question

rodbolt,<br />Can you give me a few more details about using the Delco EST dist with the OMC ESA/interupt/overstroke setup.<br /><br />Do you eliminate the ESA module?<br /><br />Is the wiring similar to Dons with one end of the circuit connected to engine ground and the other end to ???<br /><br />Dave

 

[Don S]

Re: 88 OMC 5.7 cobra shift question

Nothing so far has been discussed regarding the EST ignition system set up for the shift interrupt system. Since OMC never used the EST, it's a "work with what you have and adapt as necessary" type project. What engine do you have it on?<br />Basically the method discribed above is used to eliminate the ESA module and use the Mercruiser Thunderbolt IV distributor and Mercruiser method of using the shift interrupt system on an OMC.

 

[rodbolt]

Re: 88 OMC 5.7 cobra shift question

hello<br /> nice simplification Dons<br />captnemo<br /> this aint voodoo. yes the same swicth set up will kill the ign on an EST system.<br /> but if you already have a working TB4 why change ?

 

[CRANKIE]

Re: 88 OMC 5.7 cobra shift question

don, after installing electronic ign what would you do? use esa with resister/diode fix. or remove esa and use omc interuptor/overstroke switch.

 

[wellcraft 185]

Re: 88 OMC 5.7 cobra shift question

Right back again after a nights sleep and a days work , Thanks for your latest input guys and sorry to dissapoint tommays its not quite that bad!.<br />Don I have just gone over my motor ect and can confirm evrything is "exactly" as your first pic of the thunderbolt ign set up and they are useing the omc interupter switch in place of the shift cut-out switch in the diagram. They have left the "overstroke" out of the loop and have pulled those wires from the plug.<br />The wires used are...<br />"A"&"B" are not used.<br />"C" is grounded & "D" goes to white/green on distributor.<br /><br />I also have noticed releasing the power of the spring that holds tension on the activating arm that operates the switches it now operates when placing "in gear" also?. PLEASE NOTE..this is without engine running and as don has said before this should only activate when coming "out of gear" with boat in water under normal loads!. To which I will try this weekend at the lake. This leads me to believe I have released a little to much tension from the spring causing it to be far more sensitive but is an easy fix to change back.<br />And Rodbolt, yes I agree if it works ok there is no need for change its just that I dont believe it was working at all when the boat was purchased hence me haveing to turn the idle down to make out of gear changes easier.(my cables are all fine so at this stage are keeping them out of this)<br />Untill now I didnt know much about how it "should have worked" but after all this good info you guys have given, now can put it all into practice and see what a few tools and a day at the lake can produce.<br />So after all this I know what has to be done and what I need to do to try and sort it so at the end of the day if I accomplish nothing mechanicly I have learned allot from your input and will continue to run it as it is and hope for the best .<br />Also one last thing as Rodbolt said....<br />""for captnemo's benifit.<br />the cut out sometimes will remain ON when in gear and moving the throttle. the overstroke switch opens the circuit to allow normal ign operation.""<br />yes it activates at begining of movement and clicks off in a split second (guess this is good and how it should work!) but half way through throttle it "re-activates" and would hence cut the engine at 1/2 throttle so guess this is where the overstroke comes in to "over-ride" the grounding from the interrupter switch untill comeing off the gas.<br />I will wire in the other switch Don as per your pic and go from there .<br />Anyway thanks a heap and if anyone else wants to add please do but untill the weekend comes I cannot water test for exact results. <br />regards<br /> mike

 

[rodbolt]

Re: 88 OMC 5.7 cobra shift question

captnemo<br /> that was the whole point of the overstroke switch. to prevent ign interuption during anyother operation other than disengaugeing any gear while going to nutral. if the switch is adjusted properly it will overide the inturupter.<br /> but if your cable is sticking or the bellcrank bushings are bad it will self destruct anyway. good luck and check it carefully

 

[Don S]

Re: 88 OMC 5.7 cobra shift question

PLEASE NOTE..this is without engine running

I think one problem you are having is not knowing when you are doing something wrong.<br />If you shift into gear with the engine not running, the dogs (clutch) in the drive won't mesh and of course the switches will be activated because the cable is now on a bind.<br />You need to read Stuart Hastings section on adjustment and get it done properly, not by adjusting it to the way YOU think it should be. The Cobra drives are a pain to adjust and get right, you start taking short cuts or doing things you shouldn't and it's going to cost you lower gears.

 

[olbuddyjack]

Re: 88 OMC 5.7 cobra shift question

I also have noticed releasing the power of the spring that holds tension on the activating arm that operates the switches it now operates when placing "in gear" also?. PLEASE NOTE..this is without engine running and as don has said before this should only activate when coming "out of gear" with boat in water under normal loads!.

The spring tension could be ok. With the engine off the gears may not engage, creating extra drag on the cable, causing the switch to activate. Check it running.<br />Hooking up the overstroke switch sounds like a good idea. I read that OMC came out with a new improved ESA module that didn't require the overstroke switch which may be why its unhooked. In your application it may be necessary. Sounds like all you gotta do is a little tweaking on the switches and it'll be ok. Good luck.

 

[olbuddyjack]

Re: 88 OMC 5.7 cobra shift question

oops, I guess you beat me to it Don. I shoulda hit the refresh button first.