1962 340 hp tune up

[Dino L.]

I have a restored car, everything rebuilt or new. The car has 2000 miles on it and developed a miss. I replaced the dated wires and Delco plugs and it ran so much better for a bit, now it has low power and misfire at low rpm 1200-2200 with an occasional backfire on a full throttle rev.. I replaced the points condenser with no change. The car seems to run a bit better cold as it heats up it becomes worse. Dwell/timing/ gaps all set. It has a rebuilt dual point distributor. Carb is rebuilt and has run flawlessly since new…your thoughts on an approach to diagnose this issue would be appreciated.

[Mike E.]

Reproduction coil, perhaps? When ignition breaks down with engine hot more so than cold, that’s makes the coil a possible culprit.

[Jim L.]

In the thread about a Fuelie with Pertronix I wrote:

For all dual point distributors, I recommend disabling the leading set of points and operating on only the trailing set. Doing this precludes an unusual and difficult to diagnose failure mode peculiar to the way dual points operate.

The symptoms you describe are consistent with those observed when the above mentioned failure mode occurs. To eliminate this failure as a possibility, you could (and should) disable the leading set of points, reset the dwell on the trailing set, and reset the distributor timing. Then, of course, evaluate the results.

Even if the dual points have not failed, you'd be well served by leaving the distributor configured as a single point unit.

Which set is the leading set? Well, on a fuelie dual point distributor of the era, the leading set is the set closest to where the coil(-) wire enters the distributor base. It's probable that the same set is the leading set in your distributor also.

[Terry D.]

Did you try replacing the coil? As mentioned earlier by Mike

[Bruce W.]

Dino, I had the exact problem. as it turned out it was the coil. once the car was hot it would break up. If you have a reproduction coil they are made in China and are no good.
Bruce

[Duke W.]

Look at this nearby thread... similar problem...

https://www.forums.ncrs.org/forum/te...��

Duke

[Joe M.]

What ignition wires did you use?

[Dino L.]

Thanks everyone for the tips....I wanted to give you guys an update....First off the plugs are Champions and the wires were Delco's. I set the dwell on the dual point after filing the tips and all is well. Timed it, all distributor parts and pieces look and check as new. Problem still exists. The more I thought of the problem, it felt that the idle circuit or accelerator pump circuit on the AFB may be an issue as it runs good on mid to full throttle. So I opened up my restored AFB, that looks like new outside...its about 5 years old. Well the Ethanol gods wreaked havoc on the accelerator pump leather expansion spring...it was totally rusted and in pieces and the check valve was rusted shut, with pitting in the bottom of the bowl and slight damage to the float...I am in the process of getting the necessary rebuild parts and pretty sure this will solve the miss and stumble at low rpm.... more to follow. Thanks everyone for your input. Dino

[Duke W.]

It must have been rebuilt with a decades old zip kit. E10, which was referred to as "gasohol" back when it showed up in some markets circa 1980. Since that time fuel system elastomers have upgraded to compounds that are resistant to ethanol degradation.

Hopefully the new parts you obtain will appear to be some sort of rubber, and none will look like "leather".

Duke

[Mark E.]

Dino,

I'm glad you found the possible culprit. Let us know how it works out.

A lesson I learned about ignition points: don't file them. If filed they tend to not maintain dwell and deteriorate quickly.

Just replace them if worn or burned. They're not expensive.