i have a holley 750 VS on a 350. its got trick flow 23* heads, XE274H cam, weiand stealth intake, crane 1.6:1 roller rockers, TES headers and so on. I'm been informed that my carb may be too big for the setup i have. Being that i don't want to buy a new carb, is it possible to down jet the carb to run more efficiently. if so, how far should i downjet it.

 

Yes its actually VERY reccomended that you rejet your carb for any setup. Most auto parts stores stock holley jet kits and they are always usefull. Just pull your fuel bowl and unscrew the jets then test what size you might think will work. No one can say for sure what jets you need so you need to test.

 

Just remember when you are putting in new jets you are just taking away gas. NOT AIR!!! If you go to lean, you will loose power in upper rpm's. I think I have read something on this board that a dual plane intake can use a smaller carb than a single.

 

You can jet it down and lean out the idle mix, that will help. also try changing the vacuum secondary springs so that the secondaries open up when the motor needs it. Drop the jetting in two step increments and you will get there. You will probably wing up in the high 70s for jet size.

 

I run a 750 Holley VS with a Proform main body on what used to be my stock L98 350 and get the "its too big" crap every time I tell people what I run. As long as its tuned right it'll be the most perfect carb you could imagine. My car got more MPG with the 750 than it did with Tuned Port fuel injection (as long as I didnt let them secondaries open up )

Definately go buy a box full of all the different sized jets ($30 or so) and buy a box full of secondary springs. It would also be a good idea to buy a "Quick Secondary Change Kit" so instead of having to take your carb apart to change secondary springs you can just undo 2 screws.