62 Afterfire through exhaust

[Bob H.]

I had the intake gaskets changed last year for a similar problem. the gasket was leaking between 6 and 8. The has has been running great.

While driving the car recently and it running fine, it started to backfire and bucking when taking off . I nursed it home and after letting it cool down it seemed ok. However, after it is hot, I can now hear like an afterfire pop in the exhaust and the idle is not as smooth. It certainly seems to be a heat related problem. Do you think I could have an intake gasket problem again or should I look elsewhere? Points,cap, condenser, wires, etc were all new last year. Thanks for any input.

[Chuck L.]

Re: 62 Afterfire through exhaust

Sounds like it could be a timing problem. Have you tried adjusting it? Also, if you have a glass fuel filter bowl ahead of the carburetor, it may have dirt particles in the bottom that only plug the fuel line when you accelerate. Had this happen on mine twice due to dirt from the fuel tank. Ran fine at slow speeds until I gave it gas. It only takes a slight amount to clog your line. Just take the bowl off, see if there is sediment, and clean it to see if it works better.

[David H.]

Re: 62 Afterfire through exhaust

Bob, I am certainly no expert on these cars yet, but my friends '61 started doing the same thing as you describe. It was running fine and suddenly developed the afterfire you speak of thru the exhaust.
We discovered an issue that seem to have caused it.
The exhaust heat riser was stuck closed. We removed it and with penetrating oil loosened it up so it would work properly. You can check to see if it is stuck closed by checking the temperature of the passengers side tail pipe compared to the drivers side tail pipe. I believe it was after warm up both should be hot. If the valve is stuck closed, the passengers side will be exhausting cooler than the drivers side. Some one who knows more about this can jump in here and correct me if I am wrong. Hope this help you some.

[Bob H.]

Re: 62 Afterfire through exhaust

Thanks for the replies.

I double chaecked and don't have a heat riser. Also, I did clean out the fuel bowl and install a new filter. Any other thoughts are appreciated.

[Timothy B.]

Re: 62 Afterfire through exhaust

Bob,

I would take the points out, file lightly and reinstall. Set dwell and timing before you start$$$. If the points are pitted, replace them with NAPA brand or consider a breakerless switch.

[Terry D.]

Re: 62 Afterfire through exhaust

Bob
What motor is in the car? Solid lifters or hydraulics? Agree you should check timing, points, etc. first but a compression check should be included in that.
Terry

[David Z.]

Re: 62 Afterfire through exhaust

Just had a similar issue , sounded like one cylinder afterfiring at a certain fixed rpm value when the car got warmed up....strange, but after trying a number of things a new distributor cap finally fixed the problem.


Regards, Dave Z.

[Stuart F.]

Re: 62 Afterfire through exhaust

David;

Are you implying you had crossfire? Did you check your old cap for signs of leaking? perhaps a red dust or powdery substance inside the cap? I found this to be more common with the caps of the late 80's that sat flat on the distributor (the ones used after the large HEI units). Never had that problem with 50's, 60's and 70's caps, but heard of it being possible. My 87 Caprice V8 was always doing that, specially after sitting awhile or when there was a major weather/humidity change. The thing would hardly run until I cleaned out the cap. Really bad design, that one, but a similar problem can happen with earlier models, specially those that are neglected.

Stu Fox

[Bob H.]

Re: 62 Afterfire through exhaust

It is a 340 HP. I had electronics in it and put the dual points back in to eliminate it. I will cange the cap although it is new repro. It certainly seems heat related because it is fine until driven and at 175 plus degrees. That's when it starts.

[David Z.]

Re: 62 Afterfire through exhaust

Stuart....I am not really sure if it was crossfire or not,it sounded like it was afterfire from only one cylinder on the passenger side bank. Cap was a relatively expensive incorrect aftermarket product and was not more than a year old,it had been used in conjunction with a not so good rotor. When I opened the cap there was evidence of metallic deposits on the inner tower terminals. Replaced that cap with a cheap one that was on the car when I got it, and all was well again...

Also, this was a single window cap on a dual point 914 distributor...anyone else had difficulty getting a cap to seat correctly due to fouling on the condensor hold down screw? I had to grind a small cutout to clear it.. of course this may have been contributing to the problem, but is certainly seemed to be a snug fit on the distributor body once done. I now have a couple of NOS D324 caps so I will see if this is also an issue with these... I guess it could be that the condensor hold down screw is incorrect also.... maybe the head is too large..?

[Greg S.]

Re: 62 Afterfire through exhaust

Coil may be the culprit. It may act up when it warms up. I had a new coil that went bad shortly after installation. It caused misfires and would shut down completely when hot. Engine would restart and run after coil cooled. I bought an original 109 coil and problems disappeared.

[Joe C.]

Re: 62 Afterfire through exhaust

Afterfire is usually an indication of rich mixture, which continues to burn within the exhaust pipe, on coasting with the throttle "closed" (well, not closed for some of you more anal types......but in it's idle position). Is this what you are experiencing? Answers will be "all over the place" unless you can be more specific in your description, and/or include an audio file of the phenomenon.