Holley 750 or 850 Pros/cons

[chevy2480]

I would say yes because they are contoured better for air flow. I would run a 72 primary and a 82-84 secondary and 50cc acc

 

[khan0165]

A larger pump diaphram might improve throttle response off the line, as it will give you more fuel per squirt. However, before playing with that, try a more aggressive pump cam.

I am using 73/83 jets on mine, and just put in 75/85s because it was running lean. You might need something similar, or even more. I believe stock 750 jets are 68/76.

How do your spart plugs look? Are they showing signs of fuel starvation?

 

[dogsht]

Good input. All I know is over the years I have seen many examples where the math says 700/750 and everytime that people try both the 850s go a little faster at the track. I have learned to pay the most attention to the maximum vacuum you can get it to pull. A little more than ideal and you can bet you will find at least a 10th with a bigger or at least slippery er carb. If the motor has to suck hard to get the air & fuel it wants your leaving power on the table.

 

[khan0165]

yeah, I'm just starting to learn this stuff...
last year, the car was having big bogg problems, and 60' was terrible. So I've been working on idle vacuum, idle mixture, and pumpshots.

... who woulda thought the car's idle effects how the motor reacts on a quick lauch of the throttle.

I've since then resolved the bogging and poor off-line characteristics. Now I'm trying to sort out fuel starvation at top end.