Stooney

I currently have a 650 cfm Holley on my 305 and am told that it is too much. I'm told I should go with a 500 or 550 cfm. Any opinions?

gkull

My 283 ci Vette had the dual four barrels from the factory and it ran really nice.

It is not really so much the size of a carb, but the tuners ability to make what ever he has work. If it's a Vacuum Sec. carb you should be fine. Smaller carbs tend to run better at lower rpm though.

sturgeongeneral

I have run the 650 on several 305s and was very pleased with the results. Even had the marine version on a boat with exceptional performance.

wiseman79

570 street avenger.

baxsom

I have this one on my 68 mustang with a 302. it runs perfectly.

wiseman79

I had the 670 on my stock 270hp 350 and performed great, had the 870 version on a 406.

lars

gkull is correct: Properly set up, pretty much any size carb can be made to run fine. But a "correctly" sized carb is easier to set up right, and is more forgiving of tuning errors. Assuming your 650 is a vacuum secondary carb, there is nothing wrong with running that on a 305 - it should run just fine. I doubt you'll see any positive change dropping down to a smaller carb, since the vacuum secondaries on your 650 will never open up to the full 650 capacity of the carb. If you are having problems with drivability, you'd be better off correctly tuning and setting up that carb than switching over to another carb, which will also need to be set up and tuned correctly...

Lars

Stooney

Thank you all. I've been running rich so I went ahead and put smaller jets in the carb (3 steps down) and we'll see how this does for now. I'll have somebody who knows what they're doing take a good look at it tuning wise.