marky mark

This is somewhat of a follow-up to the "What coil to use?" thread.

I replaced the coil, plug wires, plugs (A/C R44XLS), replaced ballast resistor with a Mallory ceramic unit. This is on a newly rebuilt 427 big block. I have previously had to replace the dist. cap and rotor on the Mallory Unilite distributor. Timing is at 9 deg advance (base) with 36 total in at 3000 rpm.

The engine ran very well for about 20 minutes then I noticed a slight mis-fire at idle. The idle became rougher so I say mis-fire, although I guess it could be the carb. Anyway, I checked timing and noticed the timing mark (at idle)kept moving up and down 2 or so degrees and would not stay in the same spot. Is that normal? I've run out of solutions, although I will replace the dist cap & rotor tomorrow in case that's the problem again.

What could be causing a low rpm "shake" or mis-fire? The car runs very strong at moderate to full throttle. The plugs had a consitent tan color to the ceramic but showed some signs of fouling and (perhaps) un-burned fuel on the threads by the tips.

Is this a problem with the electronic distributors? Would a modern points or double points system be the way to go? I don't plan on exceeding the 5500 or so redline. Is there any way to boost the voltage to the coil?

Any opinions appreciated. Regards, Mark :flag :chevy

Eric 96

Mark, I had the same thing on my '70. It turns out, I took the primary bowl off my Holley, and blew out all the idle port with compressed air. Guess what? Smooth Idle again. It was the idle circuit in the carb...not timing at all.

Alwyn678

I had a pertronix unit in mine...an ignitor II and the car would have a miss at idle and eventually shut down when it got hott...I put the points back in and WAAA LAAAAAAAA............She runs perfect

micks69

Have you checked for vacuum leaks around carb base, intake manifold?

marky mark

No I haven't. How does one go about checking for vacuum leaks? I know that when I have vacuum gauge attached that (at least at idle) it won't stay in one place in that it moves up and down. Also, I really need to have Lars fix my carb. Someone mentioned vacuum leaks caused by the carb. Is that possible???Thanks.

Regards, Mark :flag :chevy


[Modified by marky mark, 4:49 AM 11/22/2001]

killain

I think from what you say, you have a carb that needs a overhaul.