Need some help, if I stab the gas quickly when the engine is at idle, it doesn't pick up right away and typically sputters and almost stalls. I'm not sure if it is an ignition or fuel issue.

Specs are as follows:
1987, 460 - stock bore and stroke, new bearings and piston rings, stock heads with mild exhaust porting (removed smog bumps, smoothed valve guides, etc) intake ports cleaned up

Holley 770CFM truck avenger carb

Dura Spark ignition, nothing special, new distributor and module

Weiand Stealth intake

Heddman full length headers into high flow dual inlet / outlet cat with Dynomax muffler

Cam specs:
Intake Duration at 050 inch Lift: 218
Exhaust Duration at 050 inch Lift: 228
Duration at 050 inch Lift: 218 int./228 exh.
Advertised Intake Duration: 276
Advertised Exhaust Duration: 286
Advertised Duration: 276 int./286 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.503 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.503 in.
Lobe Separation (degrees): 114

No EGR, No A.I.R. pumps

Manual tranny (T-18)

Double roller timing chain installed straight up (no 8 degree retard)

Ignition timing set at 8* BTDC

I'm kind of worried that the carb might be a little too much, but it was what Holley recommended for the engine.

The only other thing I was planning to change was swapping out the stock can type coil to a TFI coil that I had from the EFI 351 that was in the truck to try and get a little more spark energy.

Any thoughts / ideas? If I hold the engine RPM a little off idle (above 1200 or so RPM) there is no sputtering if I rev the engine.

Thanks,

Dave

 

Quick update just in case anyone else has a similar problem.

Vacuum advance was plugged into a full vacuum source, changed it to the vacuum port meant for the distributor on the holley carb. Still didn't fix the problem completely.

Adjusted vacuum advance with allen wrench in vacuum port on distributor until the sputtering went away.

I'm assuming that I had too little vacuum advance.

 

I have the same problum. I had to set my timing all the way up to 20* untill sputtering went away. Seems too high to me. What size allen did you use and what way did you turn it? I need more advance under a load but not 20* initial timing

 

i think its starting to flood out since it only does it at low rpms... you could change the carb to a 600-650 or change out the metering block