I'll be hitting up the track tonight with my setup.

350

Vortec heads
XE274
Performer RPM
Holley 750DP (were 72's 80's, now 70's 76's)

Wondering what I should do to jet it down even more. I believe its still running pretty rich. But I dont watn to risk going to lean. For a ballpark figure should I jet it down another 4 jets on each side?

Any ratio I should keep between the primary and secondaries?

Thanks.

 

Do not jet down any further. You're right in the ball park for a 750DP with your combo. Definately do not jet down 4 sizes. Something is wrong if it's very rich with that combo.

Where is it still rich? Are the float levels set correctly? I prefer 1\16" below sight plug threads on the Primary side and about 3\32nd below sight plug threads on the Secondary side.

Make sure idle mixture is set correctly and you should be running whistle vents or a looped piece of fuel hose between the two float vents. Cut a hole in top of hose for venting. This stops fuel from spilling out of Primary vent and into airhorn on launch.

Accelerator Pump setup is critical. Don't confuse a rich pump shot with a rich fuel curve. Has tricked lots of people.

Make sure float bowl screws are good and tight...not just snug....TIGHT!! Spray the air bleeds in the airhorn with some carb cleaner. These will varnish up after a time and will cause the car to run rich.

What is your fuel pressure? Should be no more than 6.0 to 6.5PSI max at idle. 6.0 psi is more than enough. Too much fuel pressure will cause float levels to creep and it will never be consistant.

Lots of info on setting these up. Check these links out:

Holley Tuning

I really need help with my Holley