hei ignition retrofit

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capt.snappy1

Cadet
Joined
Oct 31, 2022
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8
350/260 hp mercruiuser alpha one gen one drive. had issues with stalling/hard starting with oem thunderbolt 4 ignition system. installing hei distributor but confused about hookup? hei has 3 wires outside distributor but when pigtail is plugged into unit only one red and one green remain? no instructions came with new distributor? ideas? thanks guys! happy july 4th!
 
Bondo

Bondo

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70,958
capt.snappy1 said:
350/260 hp mercruiuser alpha one gen one drive. had issues with stalling/hard starting with oem thunderbolt 4 ignition system. installing hei distributor but confused about hookup? hei has 3 wires outside distributor but when pigtail is plugged into unit only one red and one green remain? no instructions came with new distributor? ideas? thanks guys! happy july 4th!
Click to expand...
Ayuh,..... Welcome Aboard,...... Who's Hei,..??
 
Bondo

Bondo

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Ayuh,..... Tach is usually grey,.....
 
Scott Danforth

Scott Danforth

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Only one I know that is marine rated is DUI. Davis Unified Ignition
 
matt167

matt167

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A team performance is a skip white type deal. If it says marine rated it’s a fake rating
 
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dubs283

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Jul 27, 2005
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5,322
Dang

Shoulda snapped a pic of the mie powered Arabian last season

233 ford, Rochester and some kind of ignition with coil on cap that said simply "marine" installed by an auto/marine place

Sadly the boat is now in TN, I think
 
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smokercraftv6

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Joined
Jul 14, 2012
Messages
27
Hello everyone
Last year I replaced the coil, distributor and thunderbolt 4 module.
Mercruiser V6 alpha one. Module was new OLD stock. This year put boat in the water and ran great x 3 miles and again Quit. No spark none at all.
I am assuming the Thunderbolt 4 unit went bad again. I hear they go bad with just age.

Mechanic say he wants to try a HEI like the Davis, but does that have a shift interrupt wire? Will it connect to the mercruiser micro switch.

How can I make sure this is not the microswitch coil or something else that had died. ? intermittently?

Thanks Brian
 
Scott06

Scott06

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Apr 20, 2014
Messages
6,440
smokercraftv6 said:
Hello everyone
Last year I replaced the coil, distributor and thunderbolt 4 module.
Mercruiser V6 alpha one. Module was new OLD stock. This year put boat in the water and ran great x 3 miles and again Quit. No spark none at all.
I am assuming the Thunderbolt 4 unit went bad again. I hear they go bad with just age.

Mechanic say he wants to try a HEI like the Davis, but does that have a shift interrupt wire? Will it connect to the mercruiser micro switch.

How can I make sure this is not the microswitch coil or something else that had died. ? intermittently?

Thanks Brian
Click to expand...
Go through the TB troubleshooting in the sticky’s it may be the sensor in distributor not the module

I don’t know if Davis can work with shift interrupt I would contact them before purchasing
 
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smokercraftv6

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Jul 14, 2012
Messages
27
Well Dab Nabit.
took a quart of electronic cleaning fluid and sprayed the grease off of the microswitch. Then a sharp thin knife and worked the plunger in and out a dozen times. Turned the key expecting NOTHING and Varoom started immediately. Well that is amazing, happy but confusing. I did not think that would happed.
Brian
 
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smokercraftv6

Cadet
Joined
Jul 14, 2012
Messages
27
Summit Racing recommended Sierra Marine Thunderbolt 4 HEI Distributors
18-5471 WITH HAS A INTERRUPTOR WIRE that will connect to a micro switch "designed for Mercruiser V6" 358.99 bucks hope this switch cleaning was all that was needed. ? if still will need module in the future....
 
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