carburetor?

Question

I just built a .350 with a 280 hydro magnum comp. cam. It has pretty much stock everything (all LT1 parts). I estimate the motor to be around 300 hp. (maybe slightly more). On first test drive it feels like it wants to go but something is missing. First of all it does not seem like the secondaries on the Rochester Quad. are opening (which would hold it back). The motor sounds/comes on very strong but nothing seems to kick open and it seems starved for air. Rochecher Quads always made a distinctive sound when the secondaries kicked in and I don't hear anything at all. By the way I bought a rebuilt carb from a reputable shop. However, it was a while ago (too long to take it back now).
1. Am I on the right track?
2. How could I test/fix the secondaries?
3. Would this motor be more head snapping if I went with another carb? If so what would you recommend? (I want max performance)

Answer 1

1. Engine off flip open the top secondary butterflies & open the throttle all the way. At the extreme end of travel the secondaries will mechanically open.

2. If not then check the secondary lockout mounted on the choke side of the carb.

3. Check that there is adequate clearance. Hold the choke open all the way, push down on the fast idle cam. Check the gap. Should be no more than .015"

4. Ensure the proper fuel metering rods are installed. Remove the rods by backing off the screw between the butterfly secondaries. Carefully remove the rods. On the side of the metering rods are two letters stamped.

Good Luck

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Answer 2

the Rochester is a good stock carb and you are right about the sound when those huge secondarys kick in (i used to run one on my Corvette)...what happens when you put the car in neutral pop the hood and hit the throttle on the carb manually?...it could be your vacuum or a linkage adjustment

Answer 3

sounds like your 4s not opening up all the way,to draw enough air.try adjusting the rod,thats hooked up to the top butterflies.what about the vaccum pull-off.