The Dodge Challenger Message Board

Trying to tune carb and ignition on new built 440. Runs fine on all RPMs but lack immediate response when hitting the floor too quick at lower RPMs. Get a first "coff" before it takes off. Guess I have problem finding the right balance between too rich and too lean by acc. pump. Have tried both Holley 750 vac and Demon 950 dp. Have noticed this in several cars (both 440s and 383s) but some respond as if they were fuel injected. Anyone with experience in this? Thanks! / Lars

You have to do carb tuning from a step by step systematic approach. So you have to do the basics first to eliminate problems from there before moving up and getting to the fine tuning of pump squirters and the like.

So you need to make sure you have no vacuum at the spark port and set the idle mixture and throttle speed/position first.

Then measure manifold vacuum and set the power valve/ load enrichment level.

Then disable the secondaries and drive just on the primaries to get your primary jet size and accelerator pump right. Last of all tune the secondaries and either the secondary squirter on a DP or the opening rate on a vacuum secondary.

It does not matter what make or model of carb you use. They all need a bit of tuning to work right under all conditions.

It is hard to go too rich on the squirters. You would notice a blast of smoke from your exhaust if it was that rich. Chances are it is too small a shot of fuel. The squirter size effects how much fuel you get and the cam on the throttle shaft dictates how fast and how long you get the shot.