Car 100% factory, meaning besides spark plugs and wires it’s all old stuff.

Problem:

After driving 45mins-1hr, car dies. Not all the time, but many times, like 40%. I pull over let it cool and it will start and drive for another 20mins or so.

Carb has been rebuilt this week and no change. Also, today when the car died I pulled the air cleaner and fuel does come out of the squirters when the gas linkage is moved.

I have not checked the spark when the car stops running as I didn’t have a spare plug or spark plug socket.

I'm guessing TI amp, but hope it’s not.

I guess I’m asking can you guys try and rank what you would check/replace in order. I don’t think it fuel related or wire harness. I don’t know for sure, it just seems the harness or fuel system either works or not. Nothing changes when I move any wires.

1- coil
2- TI amp?
3- Distributor?

 

Years Back I had a 70 Roadster. This might be related. 350 with a points distributor, I replaced the points with a TI system off of a 67 we had, I think. Worked great except when it warmed up the engine would shut off. I would play with the wiring a bit and off we would go again. I traced the issue to the wires going to the pole piece in the distributor, what I had done when I put this system together I had placed two round slip (push) together connectors on the two little wires going to the pole piece and one of those connectors lost connection when warm. Fixed the connector and everything was fine. The amps don't often work bad, they work or they don't is what I found out with bad wireing connections. The next time your engine stops check the spark. If no spark then there is an open circurt somewhere. It could be anywhere. Looking in my Haynes manual I could not find TI troubleshooting but I know I saw one somewhere, its been a while back. There was a time where you could replace the circuit board in the amp, years ago also. You might be able to pull the amp board out and look for circurt cracks. I would start with the 12volt source and grounds, clean and inspect, and check all wire connections. check all the wires closely, sometimes they can look good but the wire under the insulation can be broken, you can often tell by feeling and bending the wire. I hate intermittent shorts they are often a pain. I would start with wiring and connections. It's not likely to be the coil, pole piece, or the amp, but you can' rule them out.

 

Thank you for your reply, I plan on taking the car out today and bringing a spark checker.

Many have asked how hot the coil gets.

does anyone know the proper resistance the TI coils needs? Across (+) and (-) connectors on the coil?

 

The resistance should be typically 0.4 to 2 ohms. There should be a ballast resistor on the positive terminal.

 

Just checked and I’m getting .5 ohms.

I dont think the car has a resistor it’s a T.I.

I have not checked the coil when the problem happens.

 

Based on what you said about heating and cooling, if you can't find any wiring connection problems, then it might be time to consider a component having an internal temperature related problem. I would suspect the coil first since it's in the hottest part of the region. If I recall correctly, the TI unit is on the driver side in front of the radiator mounting which should be considerably cooler than where the coil is located.

 

This might be helpful.

 

Thank you for posting.

Does anyone know what would happen if a known good coil (1.2 ohms) is used instead of a (.5 ohms)?

I believe they use a coil with lower ohms to help with high revs. Which I do t care about, I’m just trying to make more reliable.

 

I think for the price I would replace the coil. From researching the system, the point distributor and the TI system use a different ignition coil. And even if a test shows good it can still break down under heat. I had problem once with a dual point Mallory condenser, when hot it went open citcurt on me until it cooled. Your coil should read 0.41-0.51 ohms and the conventional point coil would read 1.24-1.46 ohms and they do not interchange, different windings. The TI system needs a TI coil.

 

Coil does read .5 ohms and magnetic pickup reads 570 ohms. Both seem to be correct.

It’s almost impossible to check when hot, well, because it’s very hot. The coil you can’t even touch, it’s the same temp as the aluminum intake.