[1lemans]

holley or qjet?There is more carbys out there than that.i'll probably get shot down in flames for this but i used to run a 850 thermoquad on my 467 with 3.23 gears 2.5" ram air manifolds 3" exhaust t400 and ran 12.0 112mph.Changed carby for twin 44mm downdraught WEBERS and with no timing change just carbs tuned correctly gained 30 rwhp and so far 11.8 115mph.I use my old holley for a doorstop.With the thermoquad i would get approx 260 miles from a tank at highway speed,with webers about 10% heavier on gas.

[gtofreek]

The guy I work with, Jeff Koerner, is one of the best Holley modifiers in the country. When he does a Holley, the first thing he does is remove the boosters and throw them away. He says they are not correct in the way they are made from Holley. Then he makes new ones from raw castings because he found the size and angle of the feed hole and the step size needs to be tailored to the engine combo. He plots a booster rise curve[most carb modifiers don't even know what that is] and by making his own boosters, can create a carb with a perfect booster rise curve. He also heavily modifies the metering blocks to work with the boosters. His carbs perform flawlessly. This is how it's possible to have a Holley that flows 1000 cfm on a Pontiac 400 street engine that has no bog or hesitation anywhere, or from any speed. From a dead idle in gear, mash it to the floor and nothing but RPM's and hard pulling. We put one of his carbs[950 HP that flows 960 CFM] on a stock 428 with a mild cam and the same thing as the 400. Gas mileage went way up also. This carb replaced a 650 Holley. Night and day performance difference. It was like we took a 326 out and put a 428 in! Just from a carb and intake change. It had a Performer RPM intake on it before, now a T-II.

Holley's can be made to work great at any throttle position, but it takes time work to get there.