Hi all - thanks in advance for any assistance. I'm doing tune up work on my 72 GMC (350 engine, replaced sometime in the 80s, upgraded to HEI (?)).
Since buying the truck I have replaced the spark plugs, wires, cap, rotor, and replaced the fuel filter. It made a slight difference but not much.
The truck starts and runs pretty smoothly, but does not accelerate quickly from a stop OR when already moving. It is very sluggish. Also, if I punch the pedal there is a quick drop-out, like it has died for a second, and then it revs. If I am already going (say 35 mph) and floor it, it barely accelerates. Occasionally it will backfire when I do this. It does not jump into passing gear at that speed. I am not finding any vacuum leaks.
A few concerns / questions:
1) there appears to be no choke - is this normal?
2) the 'butterfly' was so stiff (in the open position) that I couldn't move it with my fingers. I sprayed it all down and now it does move but is still somewhat stiff.
3) the carb is slightly leaky around the sides.
4) what is this blue part (pictured last) and why is it plugged up? Should it be?
Any thoughts about the carb or issues I mentioned? Should I be looking at replacing the carb yet, or rebuilding? I'm not even sure what I have, other than the brand is Holley.
I have not checked the timing yet because I don't have a timing light. I'll be working on this part.
