I recently rebuilt to stock condition a 302 GMC straight 6. I have installed a header and duel exhaust system. I have a McGurk log intake, that is setup for three Stromberg 97 Carbs. all three are rebuilt with the IDOL jets at .044" (I think, need to double check). To start things off, I originally blocked off the two outer most carbs, and just had one in the center when starting the motor. I wanted to make sure the motor was tuned in, and timing set before intruducing all 3 carbs. I got the motor running and idoling good. I added the two outer carbs, with progressive linkage. The linkage is driving the center carb, and at about 1/4 throttle, the outer two carbs come on. (oh ya, I blocked off the idol circuit on both outside carbs, and have removed the choke butterfly plate on these as well.
With the 3 carbs, It starts ok, but idols rough, almost like it's on two cyclinders. When giving throttle, it backfires out of the exhaust, and runs very rough until I can goose the rpm's up, then it revs up pretty good, and strong from there. But again, will stuggle with idol and will sputter. I have not balanced out the airflow yet, but plan on looking at this, this weekend. What steps can I take to begin to dial this beast in!! Any help is appreciated.
