carb tuning trouble

[Tim Akins]

carb tuning trouble Help Please?

I just built a new 350 roller cam , 650 QF mac. sec. it backfires out carb on hard no load quick throttle punches. Anyone help please? Comp Cam extreme energy 292 roller ,RPM Airgap Vortec port matched heads , this problem is without a load in park just stomping trottle , allso holding brake and doing burnout it does it, help please ?

 

[Tim Akins]

I have a performance HEI and do not have the vacume advance connected, could this be part of it? Also initial timing is about 12 degr.

 

[Rick WI]

Did you:
A) Set the floats, should be 1/2 up on sight glass assuming yours is set up with them.
B) Check accel pump adjustment, pump arm should activate pump as soon as throttle is moved off idle stop. Should see strong stream in throttle bores.
C) Set idle mix screws, they should fall right around 1.5 turns out from seated on that quick fuel.

The backfire is a sign of dead lean. Straighten that out first. I would suggest running the vac advance to manifold vac....especially with that cam you are running.

I assume all plugs and wires are good and connected correctly.

 

[Tim Akins]

Yes wires are all wright , bass timing is about 12 deg. no vac. advance.