I have a 750 holley withvac secondaries it is on a 460 stock pulling truck the carb is in stock form what mods if any could i do to it to gain a few more horsepower and rpms? the engine has mildly ported d0ve heads a comp cam im not sure which size,edlebrock performer intake, roller rockers, double roller timing chain timed straight up like the pre 74s and is bored 30 over with stock type pistons.we are getting about 5500rpms now when we pull.Any help greatly appreciated thanks.

 

The 750 is plenty big enough. I would say that it is possibly the valve springs that are limiting your rpm to 5500. The 460 I had would go 6200 with ease with a CompCams 268H with matching lifters and springs. I had am Edelbrock dbl roller t/c straight up as well and ran a 750 Edelbrock AFB carb and Performer intake.
You can get a spring kit and put a lighter spring in the secondaries.

 

Thanks for the reply lxman i have the light spring in the secondarys im gonna check the springs they were installed with the cam when my dad rebuilt the motor a few years back but i dont know the size of the cam as he lost the cam card im gonna pull it and find out thanks.

 

Are the secondaries actually working?