74 is Missing Bad
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74 is Missing Bad
My 74 is running bad.
Soon as I start going through the gears it starts to break up.
Here's what I have checked or done so far to correct problem.
Plugs all good and firing ok
Plug wires all ok
New carb
Checked for vac leaks
Switched HEI caps
What else should I check?
Soon as I start going through the gears it starts to break up.
Here's what I have checked or done so far to correct problem.
Plugs all good and firing ok
Plug wires all ok
New carb
Checked for vac leaks
Switched HEI caps
What else should I check?
Melting Slicks
Joined: Mar 2006
Posts: 2,248
Likes: 67
From: Warrington PA
Finalist 2020 C4 of the Year - Unmodified
If so, I would check out the ignition module, most auto stores have the ability to check out the GM modules, it may be your problem.
If you have a standard distributor, your points may need adjustment or replacement.
And switch out your fuel filter(s) and then you can check the fuel pump to make sure you are getting the correct flow to and through the pump. My $.02 Tom
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Joined: Mar 2007
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From: Bridgewater nj
Schoon, it might sound silly but do you have a separate 12volt supply going to the hei. The hot points wire is a resister wire or do you have another dizzy to swap in? It could be the module or bushing in the distributor.
I have a points distributor I can loan you if you want to rule out engine trouble.
I have a points distributor I can loan you if you want to rule out engine trouble.
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You are saying that you have a HEI distributor in your 74???
If so, I would check out the ignition module, most auto stores have the ability to check out the GM modules, it may be your problem.
If you have a standard distributor, your points may need adjustment or replacement.
And switch out your fuel filter(s) and then you can check the fuel pump to make sure you are getting the correct flow to and through the pump. My $.02 Tom
If so, I would check out the ignition module, most auto stores have the ability to check out the GM modules, it may be your problem.
If you have a standard distributor, your points may need adjustment or replacement.
And switch out your fuel filter(s) and then you can check the fuel pump to make sure you are getting the correct flow to and through the pump. My $.02 Tom
Had a spare laying around so I switched caps.
The module is in the cap
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Schoon, it might sound silly but do you have a separate 12volt supply going to the hei. The hot points wire is a resister wire or do you have another dizzy to swap in? It could be the module or bushing in the distributor.
I have a points distributor I can loan you if you want to rule out engine trouble.
I have a points distributor I can loan you if you want to rule out engine trouble.
Both distributors are new.
Can this problem be timing related?
Safety Car
Joined: Mar 2007
Posts: 3,652
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From: Bridgewater nj
Yes, it's held in with 2 little screws and a 4 prong plug. You should put a drop of dielectric grease between the module and the dist housing before screwing it down. Try a fresh 12v source from another ign source. Low voltage will have it bucking like crazy as it revs up.
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Joined: Mar 2007
Posts: 3,652
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From: Bridgewater nj
Check your power wire, I'll bet it's the resistor wire that drops the voltage down to 6-7 volts. It's enough to fire the car up and even rev it but put it under load and it will buck, jerk, fart like crazy as it revs up.
If your timing was that far off it would be more of a bog and hard starting.
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Also pulled the plugs, all are firing.
It's probably something simple, just can't pin point it.
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If both dizzys are new, I would think it's the voltage. Think of it as if your alternator was bad and your running of the battery. You start loosing upper rpm until the motor doesn't want to rev at all then dies.
Check your power wire, I'll bet it's the resistor wire that drops the voltage down to 6-7 volts. It's enough to fire the car up and even rev it but put it under load and it will buck, jerk, fart like crazy as it revs up.
If your timing was that far off it would be more of a bog and hard starting.
Check your power wire, I'll bet it's the resistor wire that drops the voltage down to 6-7 volts. It's enough to fire the car up and even rev it but put it under load and it will buck, jerk, fart like crazy as it revs up.
If your timing was that far off it would be more of a bog and hard starting.
Melting Slicks
Joined: Mar 2006
Posts: 2,248
Likes: 67
From: Warrington PA
Finalist 2020 C4 of the Year - Unmodified
yes as stated above the module is not in the cap....you need to undo the rotor to get to the cover that is over the module. Just pay attention to what you undo and it won't be a problem. Either way whether you keep the existing module or get a replacement, you need to make sure that there is lube (thermal compound) on the bottom of the module when attached to the plate. If not the module can overheat and over time will fry, therefore causing you a variety of problems and the possibilty of the engine to stop running.On my 82, I check it out every 6 months or so to make sure there is said lube there, then again mine is a "dd" doing about 24,000 miles per year......good luck...............................Tom
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Hi Schoons,
Your 74 originally came with a separate coil.
It had a yellow and a cloth covered black/pink wire connected to the positive side of the coil. The b/p is a resistor wire.
You will not use either of those wires with the HEI.
Run a separate wire from the IGN terminal (in the center of your fuse box) to the battery connection on the HEI because HEI needs full battery voltage.
Not sure if that will fix your problem but you'll have it wired correctly.
Regards,
PG
Your 74 originally came with a separate coil.
It had a yellow and a cloth covered black/pink wire connected to the positive side of the coil. The b/p is a resistor wire.
You will not use either of those wires with the HEI.
Run a separate wire from the IGN terminal (in the center of your fuse box) to the battery connection on the HEI because HEI needs full battery voltage.
Not sure if that will fix your problem but you'll have it wired correctly.
Regards,
PG