78 cutting out when warm
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
Won't crank?
Or Won't start?
Your new IGN project has nothing to do with the cranking system.
But a whole lot to do with the starting up system.
Did you find some Heat Sink Compound for the Modge?
Not exactly found on every shelf in stores.
Or Won't start?
Your new IGN project has nothing to do with the cranking system.
But a whole lot to do with the starting up system.
Did you find some Heat Sink Compound for the Modge?
Not exactly found on every shelf in stores.
Race Director
Joined: Mar 2017
Posts: 11,953
Likes: 4,510
From: Virginia
At least we know why the vacuum advance can was disconnected.
Do you have photos of (or part numbers for) the old and new HEI module and coil? Were you ever able to figure out what the previous mechanic did?
I think everyone expected you to have a stock or stock+ engine. Certainly no one expected that supercharger.
How did the car run before it was serviced?
Let us know what you find with the multimeter!
Do you have photos of (or part numbers for) the old and new HEI module and coil? Were you ever able to figure out what the previous mechanic did?
I think everyone expected you to have a stock or stock+ engine. Certainly no one expected that supercharger.
How did the car run before it was serviced?
Let us know what you find with the multimeter!
Thread Starter
Advanced
Joined: May 2023
Posts: 88
Likes: 22
From: St Louis
Sorry, it’ll crank, just not fire. Bad choice of words. It would start fine before, was just rough after about 20 minutes. But now it’ll just crank and crank but not fire. Obviously it’s something with the distributor. The only thing I changed were the coil and ignition module. Will have more time to mess with it this weekend.
The supercharger is only putting out around 4lbs right now. Nothing crazy.
The supercharger is only putting out around 4lbs right now. Nothing crazy.
Last edited by PhenyxC3; Mar 21, 2024 at 09:15 PM.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
This should be easy to diagnose. Only two changes made.
Under the coil is a bushing (spring). Or should be.
All color coded wires from coil into the dizzy cap in the correct position as before?
Wire harness from engine bay to cap get flipped around 180* by accident?
(I labeled that wire terminal clip which way it goes. Towards cap or away from cap).
Modge wire connections correct and tight?
Apply Heat Sink Compound?
Under the coil is a bushing (spring). Or should be.
All color coded wires from coil into the dizzy cap in the correct position as before?
Wire harness from engine bay to cap get flipped around 180* by accident?
(I labeled that wire terminal clip which way it goes. Towards cap or away from cap).
Modge wire connections correct and tight?
Apply Heat Sink Compound?
Thread Starter
Advanced
Joined: May 2023
Posts: 88
Likes: 22
From: St Louis
Frayed wire running to the ignition module. Fixed that, and it fired right up. Not sure if it was the coil or the module causing the initial issue, but it is running MUCH smoother, and starts almost instantly. All the advice is much appreciated.
Thread Starter
Advanced
Joined: May 2023
Posts: 88
Likes: 22
From: St Louis
Unfortunately the initial issue is still present when it gets warm. Any other suggestions on what do check? It’s definitely electrical. Coil, cap, and module have been replaced. Starts cutting out after about 30 minutes, and will even die.
Race Director
Joined: Nov 2006
Posts: 13,258
Likes: 7,847
From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
2024 C3 of the Year Finalist- Modified
2022 C3 of the Year Finalist - Modified
Cruise-In VIII Veteran
There is another winding in there. It's the pick-up winding . The two wires on the backside of your module go to that little winding that's basically around the distributor shaft. Not a common one but I have seen them fail. Also depending on a lot of things you could possibly have a new part that is also no good. I've had that happen!
if I were you, I would borrow a HEI from a friend or club member just to test. Swap out the whole distributor and go for a drive. If that fixes it, it's your pick-up winding or you got a bad part.
if I were you, I would borrow a HEI from a friend or club member just to test. Swap out the whole distributor and go for a drive. If that fixes it, it's your pick-up winding or you got a bad part.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski