I have a 71 GS 350 9:1 comp. ,TA intake ,Hooker super comp headers, 4:10 rear, 4 spd,comp cams 268H grind, Holley 780 vac secondary carb(3310-1). Now the question is what would be good jetting for this application as well what would be the proper size of the power valves. Currently the carb has #67 jets and 6.5 power valve in the primary. And #76 jets and a 10.5 power valve in the secondary. How does this sound ? Any recommendations? THANKS for your Help John
780CFM? or 750CFM? 67 sounds a little lean. When I tuned my 600 holley it came with 67's. I found 69's were best. I drove the car at certain speeds in first gear and used the jets that gave the highest vacuum reading for that speed. Supposedly a larger carb should be jetted a little richer, and since it's not a stock moter... mine was stock 4 brl intake with dual exhuast at that time. Then I swapped to a q-jet for a while, now I have a 750 holley 3310-2. I rebuilt it and put in 70 jets, but haven't done any tuning yet.
also get the spring kit for the vacuum secondaries. That will help alot since they put a stong spring in there, bucause a strong spring will *work* on any car fine. But a weaker spring will let the secondaries open sooner, and give more power!
Run what you have now, and then read the plugs. The jets do look a little lean, but you'll be able to tell if that is the case by reading those plugs. That's the best low buck way to tell. My $.02
