engine issue

[RJRENTON]

Okay another update , then time for a nap, long night at work. I bypassed tank and ran separate gas line and it still happened. I have now pulled the carb....also pulled it partially apart and found a very small amount of dirt in each bowl....not a lot..BUT STILL. The only thing that was replaced last year was one gas filler pipe(horizontal) that was rusty, leading to the tank(problems getting in Canada at the time) . It likely had gas run through it once maybe since tank and sending unit were replaced the previous year; every piece is completely new now......I am figuring that is where the dirt came from. I rebuilt the entire car, so I do know it. That being said... I am thinking from look of plugs it was running a little rich as well. I will clean carb reassemble when I get up...if I have it in me.

You have mentioned that you inspected the carburetor....but what type of carb? Holley, original Carter, or Edelbrock/Carter/Weber.... The Carter design has several small internal orifices in the primary booster venturii, that conttol 100% of the idle, off idle fuel supply. Holley has internal idle passages in the primary metering block that are subject to dirt.
Yes...it is possible that the coil had an intermittent internal issue....test by substitution. Is the ignition system electronic or points? (sorry if I missed the response/answer)....likewise test by substitution. Just my thoughts.
BOB RENTON

 

[Dawg66]

Edelbrock 650cfm.......I tried subbing , and even converted it over with Pertronix kit. Coil tested fine too. Reluctor set, and vacuum canister checked. Have tried 2 coils now.Weekend is here so more time to look. Thank you All Again.

 

[RJRENTON]

Edelbrock 650cfm.......I tried subbing , and even converted it over with Pertronix kit. Coil tested fine too. Reluctor set, and vacuum canister checked. Have tried 2 coils now.Weekend is here so more time to look. Thank you All Again.

As l mentioned, with the Carter/Edelbrock design, 100% of the idle and off idle transition fuel originates in the primary booster venturii. They MUST BE Removed to clean. These are NOT the main metering jets. The idle fuel feed is usually a 0.035" (+/-) orifice that feeds an internal fuel air mixing orifice that is part of the booster venturii nozzles. These are NOT adjustable but provides the idle mixture needles which are adjustable. IF these very small orifices accumulate dirt or crud, very poor idle and off idle operation results and feels like a "miss" or stumble. Another possibility is the accelerator pump's inlet check valve, located at bottom side of the accelerator pump's well. If this inlet has dirt in it, the valve will not close when the pump plunger starts down and no fuel will be squirted in, resulting in a definite stumble.
BOB RENTON

 

[Ernie ingling]

A thought check timing chain slop. Put engine on tdc pull cap observe rotor movement while rotating engine counterclockwise till rotor moves. If there is more than 5 degs then chain is to slack. So timing will move can cause your problem.
Best of luck

 

[pnora]

With the Pertronix did you bypass the resistor?

 

[BLK 68 R/T]

I’m leaning towards an electrical issue, either with the ignition switch or the bulkhead connection.

 

[Danny Tuel]

Okay another update , then time for a nap, long night at work. I bypassed tank and ran separate gas line and it still happened. I have now pulled the carb....also pulled it partially apart and found a very small amount of dirt in each bowl....not a lot..BUT STILL. The only thing that was replaced last year was one gas filler pipe(horizontal) that was rusty, leading to the tank(problems getting in Canada at the time) . It likely had gas run through it once maybe since tank and sending unit were replaced the previous year; every piece is completely new now......I am figuring that is where the dirt came from. I rebuilt the entire car, so I do know it. That being said... I am thinking from look of plugs it was running a little rich as well. I will clean carb reassemble when I get up...if I have it in me.

Be sure and check that the jets aren't obstructed while you have the carb apart. Run a fine piece of wire through them as compressed air doesn't always get the job done. Good Luck

 

[AJ/FormS]

I'm with Bob; post 23 above; dirt in the IFRs

 

[hashmaker]

Has anyone mentioned vapor lock? It sounds just like my 383 '65 Satellite. When it got warm and then warmer it started running rough and rougher. Just sayin'

 

[sarjag]

I would look at the ballast resistor if you are using it and bypass it since the Pertronix does not need it. Then I would check for a bent pushrod. I had a similar problem on a 69 383 and found a couple bent pushrods. Another approach would be to try a different (known good) carb. I have never had good luck with Edelbrock carbs...on any engine.

 

[Bluenoser]

How about checking the alternator charge rate at start up and when the issues happen. Voltage should be about 14.2 or so. Long shot I know but you need to rule it out.

 

[69 GTX]

Have you checked to make sure your gas tank is vented good? It could be creating a vacuum in the tank and starving the pump.

 

[bret schucker]

Have you checked to make sure your gas tank is vented good? It could be creating a vacuum in the tank and starving the pump.

had a similar thing happen and it was starter relay located under hood on firewall by main harness also make sure voltage resistor is grounded good !

 

[bret schucker]

sorry, voltage regulator not voltage resistor !

 

[dvw]

You say the timing goes nuts? What controls the coil? The Petronics unit. Timing chain isnt going to come and go. Neither is the carb. The coil wont affect the timing. Throw a points distributor back in it and test. My bet is you'll find it.
Doug

 

[Don Frelier]

Maybe a valve guide or guides dragging/binding when the head heats up.
It seems like you should have eliminated the ignition system.
Seems being the key word here.