HEI + Shift Cutout
 

I have a Mercruiser 260, with an HEI in it. How would I wire the shift cutout for this distributor? The switch I have is normally OPEN, so I can't simply hook the positive from the ignition switch to the distributor onto the shift switch, or it would never get power.

Wire the switch to ground the - side of the coil when the switch activates.

So basically the electricity chooses the path of least resistence and grounds out, instead of going through the coil, thus preventing ignition for a split second. That makes perfect sense. Is it one of the three wires going from the internal coil to the rest of the distributor then?

Yes, one side is positive, one negative.

wouldn't that create a dead short on the pos side of the coil? it would only be a split second when the switch activates, but it doesn't take much to draw 1000A out of a marine battery through a 18ga (or so) wire. it probably wouldn't cause many problems, but if that switch gets stuck for some reason, then you could catch your boat on fire when that wire fries. my recommendation would be to wire a relay to reverse the polarity of your switch. essencially, you will be making your no switch a nc. that way you would actually cut the pos feed, instead of grounding (dead short) it.

Would a better idea be to just put a fuse inline with the wire? Solves that problem, no? Do you know which wire I need to cut? Haven't got the motor started yet, but I'd like to wire the shift cutout asap. Boat is 99% done!

the fuse would blow every time the switch activated and defeat the purpose. if anything, you would want a resistor, but that resistor would drop the voltage on the other side of the wire, and lower the coil voltage. ideally you wouldn't want to do this. really all you need to do is buy a small relay from any auto parts store ($5 max), and wire it in to open that positive path to the coil whenever the switch is activated. i did this on an older boat i had that had the same issue.

The switch is normally OPEN. So I'm not sure how I would wire a relay on it.

No, you short the (-) (negative) side of the coil to ground through the normally open switch. The coil charges when the negative lead is connected to ground, only when the connection is broken the electrical field breaks down and the secondary side fires. If you short it direct for a few moments it just keeps charging, and does not fire the secondary so the engine stumbles for lack of spark.

PROBLEM: Shift cutout. The shift cables are adjusted so when I shift, forward is forward in the lower unit, and reverse = reverse, and nuetral = nuetral.

However, the shift cutout lever NEVER MOVES, and NEVER ACTIVATES the switch. Why? I am pretty mechanically inclined but i do not understand why or how this is supposed to work. The boat shifts into gear fine, but the cutout lever and switch are doing nothing whatsoever.

3am. Going to sleep now. Tomorrow: Life jackets. Change oil in lower unit. Cover batteries. GO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Ted, my mistake :lolhit: i missed the (-) part of your first comment. you are correct, that will work.

cash, is you interrupt not engaging while you have it running on muffs out of the water? usually the interrupt wont activate out of the water. all it does is intantly cut power to unload the drive and release the dog gears in the drive. the interrupt works off of a little resistance on the lower shift cable while trying to pull the drive out of gear. the resistance goes away once out of gear, so the switch deactivates since there is no "pull" on the shift cables. The switch only works when the dogs are loaded (ie prop turning in the water). try it in the water, it should work fine.

Okay, will try looking at it in the water next time. :)

if it came out of gear the last time you used it, its working. you won't be able to get the drive out of gear if its not working. trust me, you would have found out as soon as you backed off the trailer and went to shift from rev to forward. you would end up pulling real hard on the shifter and it would go straight from forward to reverse. the only way it comes out of gear is to release the tension (instantaneously cut power to the engine) on the dog clutch to make it release. do that a few too many times and your drive becomes a really expensive anchor.

Determined to figure it out this year. Last year I could only go from forward to reverse, nuetral was only available if I started the engine. Ugh. Obnoxious.

First on grounding the coil with the shift cutout, it is not a dead short as the coil has a resistance around .8 ohms. This equates to about 15amps and is only momentary as the unit shifts.

There is no detent in the shift mechanism in the lower unit, the dog just goes from forward through neutral into reverse. The detent is in the shifter. Make sure that when the shifter is in neutral, the dog is adjusted so that it is in the middle of its travel (not very close to forward or reverse).

If it shifts fine while running isn't that what really matters? Why are you shifting it without it running? The clutch dog will engage forward or reverse with everything turning better than it will not running. If the cutout is not working, you could almost break the shifter off trying to pull it out of gear.

Also, if the cable is worn/stretched it can make shifting difficult and should be replaced.

Hope this helps your situation.

So for the shift cutout switch... run one wire to ground, and the other to the negative side of the coil, which is IN the HEI cap. Right?

I know. It's adjusted properly, in terms of the cables. The issue is right now I don't have the interrupt switch hooked up to anything... so if I put it in neutral, I can start the boat, then slam it into forward, but once in forward I can never hit neutral again. This is all because I don't have an interrupt switch, so when I pull it out of forward it requires enough force that it jumps right into reverse.

It actually isn't THAT bad. But it's not how it should be.

Yeah, mercuiser style cutout should go from engine ground to negative side of coil (whether integral to the distributor or a separate coil).

On my motor (1986) there is a 2 lug bar beneath the cutout switch that the 2 wires from the cutout switch go to. One of these screws is already grounded to the engine so don't hook the coil to this one or the coil will always be grounded and the engine won't start (coil will get very hot too with key on). Not sure if you have this type of setup.

Got it.

Like this?

http://i4.photobucket.com/albums/y14...ingdiagram.jpg

There are only two wires on my HEI dizzy, run and tach. So I'm guessing that the tach is the ground wire?

That is correct.

Works awesome! Thanks!

I;m having the same difficulty with finding my correct wires. I posted the "converting from TBI to carb" thread. The switch on my cutoff is a normally closed switch. So I'm thinking by what you all have said I do want the run the ground through it. I may think this backwards but if this is true then the current is coming from the coil and going to ground.
Cash68, Hope your day at the lake was successful.

You sure it's normally closed? All the mercrusier ones are normally open.

cash, check out these pics. I think I've tracked down the interrupt switch in the first 2 pics. Correct me if I'm wrong, it's on the inside of the starboard manifold

The only wire I can find by the Dizzy, is a white one w/ a blue stripe shown in the pictures below. It matches two of the wires from the switch (obviously it can only be one of them haha) is that what I'm trying to tie into the ground wire(-) from the dizzy/coil?

The third pic is me holding the 3 wires running from the coil in the cap down to the dizzy. The dark is ground(-), pinkish is power(+), and the one spliced with tape is the tach wire.

So presumably I'm splicing the white with blue stripe wire from the interrupt switch, into the ground wire that runs from the coil to the base of the dizzy. Right or wrong?

Ideas anyone?

machloosy,
First, is this a stock thunderbolt iv? If it is there should be a white/green wire coming from the interruptor switch. This white green wire then goes to the distributor. There is another white/green wire that goes from the dist. to the (-) side of the coil. This is how it is hooked up from the factory. If the white/green wire on the interrupter switch is just hanging in space then hook it to the (-)side of the coil.

If it is some after market/rigged dist., still hook the white/green wire from the interrupter switch to the (-)side of the coil. This will ground the ignition and kill the engine for a moment allowing you to switch in/out of gear.

The other side of the interupter switch should be hooked to ground.

It's not stock tbolt iv. Accell HEI. But that's exactly what I needed to know. I figured that was it, but want to limit splicing wires. Good to know I got it right. It'll be nice to dock w/out white knuckles

Cool, I hear ya there. Had one go bad on me once and I found that if you blipped the throttle real quick you could pull it out of gear as the engine slowed back down. I got good at that real quick.

check your shift cable to the lower unit

with no load on the prop there is no resistance in lower unit to the shift cable. so you may not see shift interrupter deflect. put it in the water. if interrupter never moves, it is hard as hell to shift out of gear. usually when you need a new cable, the cable drag causes interrupter to take too long to pop back into center (uninterrupted) position and stalls motor. EDIT; I got to bottom of first page and wrote this. then I saw 20 other posts where this was already answered.