HEI for 73 motor. I have HEI, but what are the extra wires for?

[Tom Magdaleno]

I have an HEI that will fit my 73 472 motor.  I'm not sure what year the HEI is out of, but it has four extra wires on the bottom that go to the module.  What do these do and how do I wire it up?

[Tom Magdaleno]

Nevermind, my friend just told me they go to an external module that controls spark advance, etc.  Its more trouble than its worth. 

[bcroe]

You may have an HEI from a computer controlled 368 engine.  What you want
is a 75-79 Cad HEI.  Just 1 wire.  Bruce Roe

[TJ Hopland]

There are some people that do want that 80-81 distributor so it may be worth your time to post it for sale here, or on Stampie's modified site.   Maybe someone would even trade for the one you want.    At the moment I dont have a regular one or a need for another spare electronic one so Im no help.

[bcroe]

There are some people that do want that 80-81 distributor so it may be worth your time to
post it for sale here, or on Stampie's modified site.   Maybe someone would even trade for the
one you want.   

I was thinking the same thing.  Bruce Roe

[Tom Magdaleno]

It only fits 80-81?  Ok, I'll post it for sale. I'm not sure what its worth. 
The motor is in my '56 Packard and since I hardly drive it I don't want to mess with the power steering pully, etc just to get HEI.  I'm having an expert friend rebuild the stock distributor.

[TJ Hopland]

It will fit any 68-81 472,500,425,368 engine except for the slight belt clearance issue you apparently already know about.  It only came in some 80's and most of the 81's with the 6.0 368 engine and the DEFI (digital electronic fuel injection).   The reason it has some value other than to someone trying to keep a DEFI engine alive is for people that want to do an aftermarket EFI system on an older motor.  It does not have the vacuum advance or mechanical advance, it was all done by the control module and ECU.

The 75-79 Cadillac EFI motors had a HEI distributor that was normal except they added some sensors in the stalk to trigger the injectors.   There was also another variant that had some sort of an electronic spark retard but I believe it only came on the Sevilles and possibly the 79 Eldorado with the Oldsmobile engine.

Many people have had very good luck and performance with the original Petronix I.   I hear mixed things about the II and III versions.  Same mixed results with other brands of conversions.