Crazy Ignition problems

[69mi 10]

I have 300 miles on the car(everything rebuilt) and this problem keeps popping up. This does not happen every time I drive it.

 

car starts right up, idles good , take it for a drive, everything seems good....

 

Then I notice: a slight hesitation at the light or pinging that was not there before. eventually, the car goes into serious missfire and begins acting like its running out of gas.

 

some other crazy side affects: when i stepped on the gas the radio would cut out..let off the gas radio comes back on, a few minutes later missfire(i traced this to VReg overcharging).

 

I turn the car off... check out wires, dist cap, wiggle dist..and then the car would start and run normal again.

 

351w, holley carb, performer manifold, stock rebuilt dist with pertronix ignitor and coil and wires, timing at 10 degrees.

 

I have changed dist cap and rotor, swapped points and ignitor, replaced VReg.

 

Any seggestions?

[danno 128]

It sounds like you need to do some voltage checks. You could have a low voltage that is causing the radio to die when you load the electrical system by running the motor faster. Your alternator should be able to keep up with it. What happens if you turn on the lights? Does the motor die?

 

The ignition problem might or might not be related to the electrical problem. I would certainly check both the vacuum and mechanical advances on the distributor. You will need a timing light to do this right, but you can check the vacuum advance by diconnecting the tube from it to the carb base, pull the dissy cap, and suck on the tube you pulled from the carb. You should see the timing plate move in the dissy.

 

The mechanical advance should be checked also, if you pull off the dissy cap and plate you can see if it looks ok, but a timing light is the true test.

 

Could you have an obstruction in the exhaust? A pinched exhaust pipe might also give these symptoms.

 

Could it be running a rich mixture in the carb? Pull the top off it and look to see the float is stopping fuel flow when the chamber is full. Can you smell gas in the carb when you shut off the motor?

 

I am sure others on the forum will have other things to check.

Good luck...

[prayers1 153]

Bad ground?

[Ky69Mach 10]

I know from being in the tractor business that a coil overheating will cause this type of problem, at least on a gas tractor anyway. Just an idea. I have had farmers tell me the engine would die and by the time they checked everything, the coil would cool down and fire back up only to do the same thing. You might try replacing the coil.

[fvike 173]

+1 on the coil. Test with another coil. I once helped a fellow with a '68 Mustang cab with a new coil. He was having all kinds of problems, and he thought his transmission was shot. Turned out to be a boiling coil. Gave him an old Accel coil I had lying around, and everything was fine. He was very happy, because he was 220 miles from home.

[69mi 10]

Thanks for the replies

 

I switch out the vreg and fixed the radio problem. The car shows constant 14.5 volts at the battery. Before it was registering about 15.5 volts.

The mechanical advance is 10 at idle and low 20s at 3000 rpm. Vacuum advance is high 30s at 3000 rpm. The car does not die with high elec load.

I adjusted the carb mixture with a vacuum gauge. I set it to 15 inches +-3 inches(bouncing). I do smell fuel at shutdown, sometimes. New exhaust system.

 

New ground strap between block and frame.

 

Petroniux tech said their system does not need the ignition resistor wire and that that might be lowering voltage to the coil as it heats up. I don't think that is the problem because the issue appeared when I put the points back on. Maybe the original high voltage effed up the coil.

 

I'll try a new coil and see what happens.

Edited February 14, 2013 by 69mi

[ramair351 10]

+1 on the coil also. look for leaking in the socket of the output wire. this happened to me on a new mallory coil once

[69mi 10]

Update.

 

I hope this will help someone in the future...... First i called pertronix and the tech said that the coil should be getting at least 9volts. He also told me that the secondary winding should be around 9000 ohms(the ford manual says between 7000-9000ohms). The pertronix instruction manual also says to remove the ignition resistor wire.

 

the voltage to first coil that i had bought from them was at 5.5volts with the ignition resistor wire installed and the secondary winding registered 11000 ohms.

 

The new coil secondary winding was at 9000 ohms. I bypassed the resistor wire and registered 10 volts at the coil. I think the voltage regulator overcharge screwed up the first coil, but this issue may have been caused by the resistor wire and the corresponding low voltage. I changed both at the same time, so I don't know which one was causing the ignition problem.

Edited March 13, 2013 by 69mi