At a loss
Thread Starter
Junior Member
Joined: Jan 2026
Posts: 1
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At a loss
Ive got a 84 f150, pulled a 78 351m 400 out and installed in my 84 that had a 300-6 in it from factory. Installed a hei distributor in it. Ran great all summer then just quit. Getting spark but not like I should be. It will hit after you turn the key back from cranking but will not run.
Senior Member
Joined: Apr 2023
Posts: 4,268
Likes: 1,383
From: Near Salt Lake City
Welcome to HEI diagnostics
Probably just needs a module or a stator in the distributor
I have a bunch of GM HEI diagnosis pages I can print in a few days if you are still stumped
How old is the distributor, and is it a factory GM one or a China one?
The distributor gear roll pins break off in the China ones, (they use a solid pin in the China ones, and not a roll pin like they should have)
Very common for the rotor to short out on a HEI
Symptom of a sheared roll pin or faulty module is one spark every time you hit the key but nothing on crank
Fun stuff
* Get a good used GM module from the junkyard if you need
Probably just needs a module or a stator in the distributor
I have a bunch of GM HEI diagnosis pages I can print in a few days if you are still stumped
How old is the distributor, and is it a factory GM one or a China one?
The distributor gear roll pins break off in the China ones, (they use a solid pin in the China ones, and not a roll pin like they should have)
Very common for the rotor to short out on a HEI
Symptom of a sheared roll pin or faulty module is one spark every time you hit the key but nothing on crank
Fun stuff
* Get a good used GM module from the junkyard if you need