I have a 451 stroker motor that has less than 1500 miles on it and know I have a miss cruising from a stop to about 3000 rpm, after that it smoothes out. It also seems have a slight stumble when mashing accelerator to the floor but runs great at higher RPM. I didn’t have these problems in the beginning after motor break in, just lately. Everything is new, plugs, wires, firecore distributor with 25 deg mechanical advance @ 2400 RPM, vacuum advance into timed spark port on a Quick Fuel SS-780-VS vacuum secondary carb. This carb has (74) primary jets , (82) secondary jets, Idle air bleed 70/70, Hi speed bleed 33/33, Primary Nozzle 33, Needle and seat 110, Power valve 6.5. I’m really not sure if my problem is an ignition problem or a carburetion problem. I have tried adjusting fuel mixture screws on the carb following Quick fuels instructions but it doesn’t seem to make much difference. The carb seems to be way to rich at idle and smokes at cold start. I’ve tried adjusting timing, distributor advance springs, idle mixture screws to no avail. Do I need to change the air bleeds or power valve in the carb? Or do ya’ll think it may be more of an ignition problem? Any assistance with this tuning problem would be appreciated.
Motor (400/451)10.5: 1 Compression, Mopar performance ported stage 6 heads, 1.6 ratio rockers, Edelbrock dual plane intake, Quick fuel SS-780-VS Supper street carb, Hughes Engines cam (Int lift .545”), (Ext lift .571”), duration @.050” 228/232 with 110 deg lobe separation. Hooker super comp headers, 2 ½” exhaust pipes. 727 transmission 4:10 rear gear.
If someone could give me an idea where to start to remedy this problem I sure would appreciate it.
Thanks in advance!
