GM EST Distributor Kit and Mercruiser Shift Interrupt Switch

[mwvonlehe]

I have a 1998 Sea Ray 215 Express Cruiser that I recently installed a GM EST Distributor Kit on.
5.0 Liter (305 CID), 2BBL Carb, V8, Alpha 1, Gen 2. The Thunderbolt V was giving me some problems so I decided to get a new ignition system. The installation went just fine. The shift interrupt switch works just fine.

I have a question about the wiring of the Shift interrupt switch. Instead of running the shift interrupt lead wiring harness part # 500492 from the distributor to the shift interrupt switch, (which is + voltage), could I instead just ground out the coil like in the DUI distributors?

Has anyone tried this method of using the Shift Interrupter Switch through grounding the Ignition coil on a GM EST Distributor?

 

[alldodge]

The interrupt switch is normally open and closes when shifting into neutral. It needs to send 12V when shifting to cause ignition to stumble. Don't connect it to ground

 

[Scott06]

I have a 1998 Sea Ray 215 Express Cruiser that I recently installed a GM EST Distributor Kit on.
5.0 Liter (305 CID), 2BBL Carb, V8, Alpha 1, Gen 2. The Thunderbolt V was giving me some problems so I decided to get a new ignition system. The installation went just fine. The shift interrupt switch works just fine.

I have a question about the wiring of the Shift interrupt switch. Instead of running the shift interrupt lead wiring harness part # 500492 from the distributor to the shift interrupt switch, (which is + voltage), could I instead just ground out the coil like in the DUI distributors?

Has anyone tried this method of using the Shift Interrupter Switch through grounding the Ignition coil on a GM EST Distributor?

If you get the wiring instructions for the est they will have you pick up a 12 v source like the purple igntion wire, run it through the shift interrupt and to the est distributor. When you shift out of gear and the shift interrupt switch gets closed it will send 12 v to est module to stumble the ignition

 

[mwvonlehe]

The interrupt switch is normally open and closes when shifting into neutral. It needs to send 12V when shifting to cause ignition to stumble. Don't connect it to ground

I have it set up the correct way and it is working correctly.

I am just asking if anyone has set it up an alternative way.

Such as connecting the shift interrupt switch wire to the tachometer wire on the coil with no shift interrupt lead attached to the distributor. This way when shifting into and out of gear the shift interrupt switch would ground the coil and cause the engine to stumble. There would only be the ignition harness attached from the distributor to the coil. There would be no wiring attached to the 4 pin terminal (where the timing harness attaches).

Does anyone think this would work? This is how the Davis Unified Ignition system used the shift interrupt switch as well as thunderbolt V.

 

[Scott06]

I have it set up the correct way and it is working correctly.

I am just asking if anyone has set it up an alternative way.

Such as connecting the shift interrupt switch wire to the tachometer wire on the coil with no shift interrupt lead attached to the distributor. This way when shifting into and out of gear the shift interrupt switch would ground the coil and cause the engine to stumble. There would only be the ignition harness attached from the distributor to the coil. There would be no wiring attached to the 4 pin terminal (where the timing harness attaches).

Does anyone think this would work? This is how the Davis Unified Ignition system used the shift interrupt switch as well as thunderbolt V.

Never seen the Delco set up that way. not sure why if it is working as it should -what the advantage would be?

Can only think the stumble via the 12 v supply to that input on the module is controlled/timed through the module vs grounding out for as long as the shift plate/interrupt switch is tripped by shifting. I'm sure there is some reason other than an engineer had too much time on their hands...

Its summer and your boat is working dont go looking for problems ... burn some gas and drink beer

 

[snowbrd84]

Mind posting or pming a link to the one you bought? Pretty sure my Ignition Module is not working right and thinking HEI might be the answer.

 

[Scott06]

Mind posting or pming a link to the one you bought? Pretty sure my Ignition Module is not working right and thinking HEI might be the answer.

This is the Delco EST the OP was talking about . Its a good OEM quality system that is more cost effective than replacing a Thunderbolt module (unless you can find one used).

5.7L/350ci - 7.4L/454ci GM Delco Voyager EST Distributor Kit

5.7L - 7.4L Delco style Voyager EST marine electronic distributor kit. For 1967-2011 5.7L-7.4L Engines. Includes: Coil, Spark Plug Wires, Timing shunt, Pig-tail plug, and Coil-to-distributor wire.

marineenginedepot.com

 

[snowbrd84]

This is the Delco EST the OP was talking about . Its a good OEM quality system that is more cost effective than replacing a Thunderbolt module (unless you can find one used).

5.7L/350ci - 7.4L/454ci GM Delco Voyager EST Distributor Kit

5.7L - 7.4L Delco style Voyager EST marine electronic distributor kit. For 1967-2011 5.7L-7.4L Engines. Includes: Coil, Spark Plug Wires, Timing shunt, Pig-tail plug, and Coil-to-distributor wire.

marineenginedepot.com

Thanks! Do you know if that unit has a rev limiter and integrates the existing knock sensor?

 

[Scott06]

Thanks! Do you know if that unit has a rev limiter and integrates the existing knock sensor?

no rev limiter and no knock sensor

A lot of folks in the perfomnace crowd use it because it has no rev limiter