Runs badly when she gets hot

[Mike Wilson]

Mitch: Pertronix on a 6V car was off 2 degrees at distributor.

[David Jones]

I have has a Bosch blue coil just die after running for maybe 15 minutes. This was with points on 12 volts. After the car sat for 30 minutes fired right up and ran again until it had about 15 minutes run time, after doing this three times I still did not believe it was the coil so trouble shot everything else until it was the only thing left. Changed it out problem solved so it is definitely suspect. Also the Pertronix units are susceptible to low voltage failure so if after 15 minutes there is any voltage drop at the coil because of a high resistance building up as a result of current heating and the voltage falls to 5.2 volts it will misfire constantly. Run a jumper from B+ on the regulator to coil + and see if the problem is fixed and if so look for a bad connection (a cold soldered joint/bullet connector could do it)
Lastly as Mike Wilson pointed out they did have a quality control issue some years back with some units having as much as 3 degrees difference between the magnet positioning in the rotor which can cause the firing point to vary. You can check this of course by checking the timing separately against the #1 set point by measuring the firing point on all the cylinders by moving he inductive pickup sensor too each different cyl wire.

[John Jenkins]

Regarding the Pertronix timing. It is the placement of the magnets in the magnetic ring. A replacement ring is required. If you have a distributor machine you can see the error(s).

[Mitch Covington]

I've replaced the coil and have the same behavior. It seemed to run better for longer, but after 4 miles of driving at 20-25 mph around my 'hood, it started skipping again. That night my left carb kept flowing into the engine and my garage floor, so troubleshooting the skipping issue is on hold until I get the carbs rebuilt. Will pick back here up when that job is done.

[Jeffrey Leeds]

Thanks for the update Mitch. Sorry you are still experiencing issues. Keep us posted, please.

Jeff

[Greg Scallon]

Mitch,
It sounds like you have a stuck float valve in one of your carbs which has caused the carb to overfill the bowl and then overfill onto your floor. This sounds like it could also be the cause of your skipping problem. It takes awhile for an empty bowl to overfill, but once it does, two of your cylinders will then be getting raw fuel dumped down them leading to a crappy running condition.

Others will advise you better on what to do about the stuck float. Obviously fix it, but you also want to drain and change your oil since it likely now has gas in it.

Good luck.
-Greg

[Mitch Covington]

Thanks for the update Mitch. Sorry you are still experiencing issues. Keep us posted, please.

Jeff

Thanks Jeff! While this seems like a setback, I'm learning quite a lot and having fun. I see it as an investment for the lifelong hobby of keeping my 356 alive, for a "compleat idiot".

This sounds like it could also be the cause of your skipping problem.

That would be great if this was the issue! It would make sense, I've eliminated most of the other candidates.

My carb issues are posted here, lots of pics:
viewtopic.php?f=1&t=43943&start=30

thanks all,
mitch

[Mitch Covington]

So preliminary indications are that the left carb was the culprit. I've rebuilt it and with a test drive of 7-8 aggressive miles the car is running great -- other than idling too low. I'll tune the carbs now.

I have also put in new NGK B6HS plugs gapped at .028.

I completely drained the oil and put in Valvoline straight 30w regular oil, and add some Lucas Zinc additive.

Next I'll replace the spark plug wires with the long brown connector types.

Finally... i have to change the axle boots. Lifting up the car and letting the wheels droop caused the boots to leak very badly... but that's a different thread.

thanks to all.

[Jeffrey Leeds]

Thanks for the follow-up on this problem.

And now the dreaded axle boots leaks. Everybody has a favorite sealer, and some have great success with installing the boots dry. But I've found that wiping the (all) contact surfaces with Hylomar Blue sealant has simplified the boot replacement chore.

Jeff