Holley carburetor jetting

[punkchop]

I am rebuilding a Holley carb., and was wondering what size jets i should use. Here is a list of what i got Chevy 350 engine bored .030, 750 Holly double pumper cab., Torker II intake, headers, and a 350 turbo tranny. Thanks for the help

[MagicRat]

I have fooled with many Holly carbs and I have found that all of them are jetted too rich from the factory, for a street driven car, Maybe Holly thinks all carbs are being used for all-out race cars.
I will assume you have a square bore carb, not a spread bore.
I have a Holly 750 vacuum secondary on an Olds 455 with the same mods as yours. My carb came new with 75 jets in the primary and 76 in the secondary. This was too rich. I dropped down to a 73 in the promary and the throttle response really sharpened up and the whole thing ran better. Even wide open, with the rich secondaries, it was better.
Holly does specify some 750 carbs with jets as lean as 70 in the primary. So I would suggest go between 70 to 75 and experiment. I guess go closer to 70 if the cam in your engine is mild. If the cam is really mild, a 750 double pumper is too big. When the secondaries open, too much venturi area will be exposed and the car will run slower. In this case, convert the carb to a vacuum secondary and it will run better.
Good luck

[mrselfdestruct]

i think your 750 might be big for the 350.i have a 650 on my 350 chev. and i run size 75 jets in it.it also is a d.p.in secondaries i run size 81 with the secondary power valve plugged.i also have headers and a edlebrock torker 1 manifold.it kicks rear!!

[Oldsfreak]

I am currently rebuilding an Oldsmobile 455 with edelbrock's performer intake, comp cams 280 advertised duration cam kit, rebuilt E heads, and Federal Mogulrebuild kit. My problem is that I have a 650 holley double pumper and a 750 holley double pumper on the shelf and not sure which to rebuild and use. Whats your opinion?

[72' Stang 351 H/O]

I've talked to Summit techs on the proper size of carb for my dad's 351 C and they say 600-700. 750 is way to big.