Thread: Can I tune out this bog?

Tweet

Okay, just got back from a spin...

Vac at 1100 rpm in 1st gear reads right at 4"... cruise varies between 7-11+" depending on speed and gear and "normal" acceleration is around 6". Perhaps with the right power valve and some fine tuning of the idle circuit I could bring up the idle vacuum a little so looks like I'll need about 2.5" power valve (this is the smallest they make) or a 3.5" as a number of you suggested...

When I open up the throttle vacuum goes to 2-3" depending on the conditions so I would think 3.5" valve would be better (if not 4.5"?)... I don't want to go too low for fear of risking a high speed lean out in the 1/4 mile(?)

Since I do put down a lot of street miles (drive 30 miles each way to the strip and back), I'd like to not plug the power valves if at all possible.

Pump cams are brown in #2 mounting position on the secondary and what looks like "tan" in #2 position on primary (although I don't know of a "tan" holley pump cam? Maybe it's orange or dirty white?)

Also... I took another look at the boosters and if I go with tube nozzles it would actually squirt at the side of the booster since they are mounted much higher....

Thanks for all your help guys...

Chris

BTW: since this is high altitude it is not unusual to get 1-2" less vacuum for a particular application than you would near sea level

My Holley carburetor handbook states that discharge nozzles with tubes will better direct the flow and that's how I'd go.