NEVER put a 750 on a 318........

Rat Bastid said
All 4V carbs are tested at 20.4 inches of water. IIRC that is 3 inches of Mercury. 2V carbs are tested at about 10 inches of water which is 1.5 inches of Mercury.

You can 850 CFM through a 250 CFM rated carb by running the test pressure up.

The biggest mistake in running a bigger carb than the math calls for is not getting the booster correct. You can run a much bigger carb if the booster is carefully selected and not lose a single HP down low and gain from the middle all the way up.

I’ve been saying this for — EVER!
But yet! Some people say there engine only consumes *** of CFM on the dyno, so there’s no reason to use a bigger carb. I give up, run what ever the help ya want, just don’t ask my opinion on it.

66fs said
I got tired of rebuilding them all the time to keep them to running good. Friends raced Super Stock and Stock, kinda opened my mind what was possible. I stopped reading magazines and started listening. A friend was racing a 396 in a late 60's Chevelle 4 speed and was using a 850 DP Holley. He was running real slow times, so I asked him if he had the original Quadrajet. He did, so I spent a day doing it up right. Next race day we went to the track and he had so much low end power he shredded the clutch right off the line, first run. Well, he blamed me and the Quadrajet and put the stupid Holley back on. He continued to run slow. I'm not saying a Holley won't run good or make more power, but for me, they are not worth the aggravation for little to no gain. Thermo-Quads are amazing.

Same as above! But I’ll add, it’s also amazing how well a factory intake offering will do as well. I’ll suggest it when the combo is right for it, where the focus is driving the car on the road and rpm’s on the highway or down the local neighborhood are low, there ideal. A lot is where the car/engine live and what your doing with it.