I can't track down the misfire in my car. I've replaced the coil, checked the distributor cap, inspected plugs, readjusted the idle mixture, checked the timing, checked for vacuum leaks, etc.
Its come down to this: I have a misfire or surge at part throttle. Under much harder (hard-ish part throttle it is there as well, but not really hard) throttle, it 'clears up' and is unnoticeable, but comes back again at throttle cruise or just leaving from a stoplight on a say 1/4 throttle.
I know I've asked this alot, but I keep finding little things out. It seems to be more pronounced when the engine is alot hotter.
I'm thinking I should give up and replace the plugs, but these have about 300 miles on them, and were hard to find shorty plugs for my headers.

Matt

Have you checked your accelerator pump? Take the air cleaner off. Look down the horn, and s-l-o-w-l-y move the accelerator arm on the carb. If you need to move the arm a bit before you see a squirt, you may need to replace the pump.

If it is a holley try jetting up the primaries two steps. I had a 396 that was on the edge of lean and part throttle cruise would have the engine surging. Jetting up took care of it.

Marv what are the cam specs?

Thanks for the help so far everyone.

here is a quick rundown:

460 CID BBC
Rect heads/intake
forged crank/pistons
hooker super comps
accel 574S plugs
MSD wires
MSD 6al, blaster 3, pro billet distrib.
Holley 750/850DP (750 w/ 850 baseplate)
73P 80S
Carter 120GPH street pump
Comp Cams 286 @ .006, 230 @ .050 .640 lift (hyd. roller)
Comp 928 springs

I never ran into a problem like this with the more aggressive (and powerful) UD HR4 296 @ .0045 231 @ .050 .621 lift.

Need any other info?
Matt

Mat
I'll take a guess that this happens under 2500rpm or so and at light throttle as you indicated.Your holley is a 4779dp? it sounds like you transition circut is lean enuf to make it miss.if you can like email me and i'll talk you thru the fix.

It seems as if its under 2500 rpm. And it is a 4779...

Thanks for the help, I'll email when I get back from work.

Matt