when i accelerate it pulls hard for 2 or 3 seconds then all of a sudden it feels like a decompression valve opens, but there's no pattern, no warning, i replaced the 2 main carb body seals, accelerator pump cup, the carb spacer, cap, rotor, accel 8mm wires, new coil, new hd mechanical fuel pump, new sending unit, new fuel filter, it has the stock holley 2280 untouched from factory, new alternator and battery. i have an aftermarket tach that came in the truck never gave me problems, i noticed its malfunctioning constantly since this issue occurred, just not in sync with it, it will spike to 8000 and drop back to 0, itll show im idling at 7000 and go backward as i accelerate, sometimes it doesnt work period, sometimes its seemingly flawless, i disconnected the factory choke recently because it stuck closed, that seemed to help. anything from half to full throttle, she starts chugging and backfiring, almost always if it downshifts, it appeared to b only after about 3000rpm but today it happened around 1000 to 1500. any ideas?

 

just a shot in the dark. the suction line has a leek letting air in. i had this happen on a 1965 chrysler 300 L. the steel line had a small rust spot letting air in. a bad hose / loose hose can do the same thing.

 

i will look into it tomorrow, appreciate the suggestion

 

well feul lines looked descent didnt really look at them becuase the accelerator pump went again, i cleaned the carbueretor this time reinsalled it but she is still doing the same thing hopefully tomarrow i can pull the fuel lines and look, i dont recall any rust when i did the fuel filter are there any gaskets known for going?

 

The tach might be sending u a message, maybe you have a short in the wiring somewhere.