1967 won't run after 30 minutes

[Lee B.]

Re: 1967 won't run after 30 minutes

It is on the positive side of the coil. Should it be on the negative side?

[Joe C.]

Re: 1967 won't run after 30 minutes

It is on the positive side of the coil. Should it be on the negative side?

Pos side is right, corrected post above.

[Lee B.]

Re: 1967 won't run after 30 minutes

I am going to get the alternator checked tomorrow. As it gets hot, the voltage drops. It starts at 14 or so and drops down to 12 within 10 minutes of idleing. Have a good old school place to take it to. Will let you know what they say.

[Leif A.]

Re: 1967 won't run after 30 minutes

I am going to get the alternator checked tomorrow. As it gets hot, the voltage drops. It starts at 14 or so and drops down to 12 within 10 minutes of idleing. Have a good old school place to take it to. Will let you know what they say.

Lee,
If your rebuilder determines that the alternator needs to be rebuilt, and if it is the original to your car, be sure you get YOURS rebuilt and they don't give you a rebuilt off the shelf...just a friendly heads-up.

[Lee B.]

Re: 1967 won't run after 30 minutes

I took the alternator to the shop and put it on the tester. Although it was cold (and it always works when it is cold), the guy showed me it was working better than spec. He suggested the voltage regulator could be bad. I had ruled the alternator and the VR out since John Pirkle had rebuilt them along with the starter before he died. I am going to take my spare VR and give it a try and see if that is the problem. Is there any way to test the VR?

[Joe C.]

Re: 1967 won't run after 30 minutes

I took the alternator to the shop and put it on the tester. Although it was cold (and it always works when it is cold), the guy showed me it was working better than spec. He suggested the voltage regulator could be bad. I had ruled the alternator and the VR out since John Pirkle had rebuilt them along with the starter before he died. I am going to take my spare VR and give it a try and see if that is the problem. Is there any way to test the VR?

Take the cover off and check the contacts for corrosion. The link I gave you above shows how to check it.

You should have a ground strap across the left side motor mount.

[Lee B.]

Re: 1967 won't run after 30 minutes

I took the alternator apart and everything looks like brand new. Ran out of time but will check the VR tomorrow as suggested in the article. I had looked at it on Sunday and it didn't look corroded, but I will test it. Douglas mentioned the baseplate might be warped. I have tried another carb with the same results. Not saying it is not the problem, but I have heard several times that 90% of all carb problems are electrical. I will test VR tomorrow night and report back.

[Michael W.]

Re: 1967 won't run after 30 minutes

Does the voltage increase if you rev the engine?

[Joe C.]

Re: 1967 won't run after 30 minutes

I took the alternator apart and everything looks like brand new. Ran out of time but will check the VR tomorrow as suggested in the article. I had looked at it on Sunday and it didn't look corroded, but I will test it. Douglas mentioned the baseplate might be warped. I have tried another carb with the same results. Not saying it is not the problem, but I have heard several times that 90% of all carb problems are electrical. I will test VR tomorrow night and report back.

Check your engine to frame ground as well. There should be a braided copper strap between the engine and the frame on the left motor mount.

[Lee B.]

Re: 1967 won't run after 30 minutes

I checked the ground on the left side of the engine and it is good. I checked the VR and Alternator and ended up replacing the VR with a "cheap" one from Napa. The new VR immediately gave me higher voltage readings and actually increased when the engine was rev'd. I need to change the points and coil as I think they have been destroyed during all this testing. Will do this on Sunday and give the car a test drive and report back

[Lee B.]

Re: 1967 won't run after 30 minutes

I replaced the voltage regulator with a new one and still had the same problem. As the car gets up to operating temp, the voltage goes down. It is intermittent. Does it 80% of the time. I am going to pull the alternator off my 68 GTO and see if it solves the problem. Based on another post, I ran it the car last night and could not see any random sparking in the dark. I will try this week with the other alternator unless anyone has another idea. Yesterday the voltage at the battery was 12.4 after it warmed up. Same at the alternator. If the alternator is the problem, I will try getting it rebuilt and see what happens.

[Lee B.]

Re: 1967 won't run after 30 minutes

I checked the cables and they are normal. No extra resistance (i.e. no corrosion). I took the car out this weekend and when I stop, now the car refuses to start back up. It will run okay, but I had to crank anad crank to get it to restart. I pulled the alternator off and am getting it rebuilt tomorrow regardless of how it tests. After that, I am going back to the fuel system. I cannot find it right now, but someone suggested that the car may be running lean when it gets warmed up. Every time it acts up, when I press the gas, a shot of gas comes out. So the question is: If it is running lean when it warms up, how do you fix it? Make it run too rich cold and then let it lean up as it warms up?
As always, I appreciate the suggestions,
Lee

[Michael W.]

Re: 1967 won't run after 30 minutes

The alternator, VR and battery is a red herring. Has nothing to do with the engine quitting when hot. If low voltage was the issue, there wouldn't be enough to crank.

[Lee B.]

Re: 1967 won't run after 30 minutes

So is it the carb? Fuel pump? I love this car when it runs right, but that is limited to 20 minutes a day. After that it is embarrassing to drive. Won't start, backfires, runs like crap. I am going to make the air fuel rich and see what happens.

[Michael W.]

Re: 1967 won't run after 30 minutes

I thought you had isolated it to an intermittent 12V to the coil, no?