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MSD & HEI

waldo

New Member
Joined
May 11, 2023
I recently acquired a GM HEI out of a 1976 Buick Skylark with a 231 V6. I have several questions regarding this engine.
First, the engine has a rear dump exhaust manifold on the driver's side. I would like to use it on my M38 w/225 V-6 and eliminate the front dump crossover. Will the 231 exhaust manifold fit on my 225?

Next, I have read of various ignition component failures (often on aftermarket HEI offerings). I plan to replace ALL of the electrical components during a rebuild as they appear to be all original. As might be expected, my primary interest is reliability. There are numerous aftermarket components available (as well as numerous forum posts as to their poor quality/failures). If anybody, who has first hand experience, regarding the dependability of these pieces (Coil, control module, pick-up, eluctor)(factory or aftermarket), I'd like to know about it. I intend to carry all the take-offs as emergency spares, but would rather Go Jeepin' than wrench on my dead engine somewhere west of Moab.

Lastly, I have two MSD ignition boxes (a 6A & a 6AL). I won the 6AL in a raffle some 20 years ago but never had a vehicle suitable for the box. In the box was a small catalog in which was mentioned a service for conversion of the box to an "odd-fire" configuration. I contacted MSD, however, since MSD'd acquisition by the Holly Performance Group, this service is no longer available. Does anybody out there know how to go about this modification?

I mourn the consolidation of all these aftermarket suppliers as they get gobbled up by the conglomerates. You can't get an odd fire cam from Comp Cams anymore (try getting one from anybody), or Lunati, or TA Performance or any of the normal channels. Found a cam at Isky's for more $$$$'s than Comp's full kit (Cam, lifters, springs, retainers, timing set), and it wasn't a suitable grind for Jeepin'. The lowly 225 V6, although still a popular engine, just doesn't bring in the big profits. Thank you Edelbrock. And thanks to Holly, too!
 
Regarding the rear dump exhaust, I believe at some point in the 70's GM reduced the size of the exhaust ports in the head so you have to be careful to make sure the manifold you get will cover the 225's exhaust ports.
This is the one I have and it does cover everything and clears the saginaw style steering shaft.



For the HEI: the first one I ran for years was an EBAY cheapo, but I put AC-Delco module in it and kept one module as a spare in the tool box. I never had any problems with it other than having to cut off one of the distributor cap hold down bolts to clear the intake manifold. Recently I switched to a CRT-performance brand HEI with an extended shaft (similar to the Davis DUI style) and it has worked just fine and made it easier to work on the engine and more freedom for rotating the distributor.



I am not an expert on either of your questions but at least maybe this will help start the conversation.
 
Cant help with the conversion on the msd, but i do currently have the msd 6a? Running on my oddfire. Years ago i got an hei distributor and installed it also. I noticed no difference with both so took the hei back out. I think they both essentially do the same thing
 
I honestly dont see the need for an msd box for a stock jeep application. I have run a dui hei for the oddfire for several years and zero issues. Carry a spare hei coil if you are worried about it.
 
I honestly dont see the need for an msd box for a stock jeep application. I have run a dui hei for the oddfire for several years and zero issues. Carry a spare hei coil if you are worried about it.
Agree with this post. I run the DUI HEI on my 231, and just carry a coil and pickup, but they have never been used. I also just helped my son remove the MSD from his CJ5 304 that was not running right, and used an Amazon HEI…solved the poor running and he was able to send it to a new owner…
 
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