View Full Version : HEI setup with a shift interrupter

03-31-2011, 09:37 PM
Has anyone had experience hooking up an HEI distributor with a shift interrupter switch. Have been studying the Mercruiser manual and this is what I have come up with: On some of the wiring diagrams (regular distributor and coil) the negative terminal which serves as the tach signal is also routed to the shift interrupter, I'm assuming that when shifting forward/reverse the switch temporarily grounds the coil and unloading the engine. On a Thunderbolt ignition the shift switch comes directly off the distributor, again assuming the system goes to ground and unloading the engine allowing for a smooth shift. An HEI has a power terminal and a tach terminal. Question is if I hook the shift switch off the tach wire will it ground the system momentarily to unload the engine for shifting?

Greg K
04-02-2011, 07:23 AM
Simple answer...yes

04-02-2011, 08:04 AM
HEY someone chimed in! Thanks. Have done lots of research and some say that with the hei the shift switch cuts the engine completely off. Could that be do to poor cables or bad cable adjustment? So new to this car engine in a boat thing that I'm tryin to cover all my bases, don't wanna be working on this thing down in the hole, I'm too damn big for that!

04-02-2011, 09:12 AM
Ground the tach wire at the interuptor switch.Ran one like that for the life of the 350 motor.Always carried a spare module never used it.

04-02-2011, 10:59 AM
What HEI system are you using?
Delco Voyager system?

04-02-2011, 01:53 PM
Using a standard hei distributor no vacuum advance only mechanical. Just finished rebuilding it. Was a good core with no guts. Brand new coil, rotor, cap, module, condenser module, pick-up coil.

04-02-2011, 04:51 PM
One suggesion before you wire it up is to check the type of interupter switch you have. On my alpha the switch is normall closed and opens when you go to shift. If you are going to wire as suggested above and you have the same switch as mine the coil will always be grounded.