logan_abrams

Ok guys- I need your expertise. So I got a Holly 670 Street Avenger on a 383 LT1, camed(Lift: .576"/.570), with Edlebrock performer LT1 heads and hooker Super Comp LT and a 4 inch mufflex exhaust. I am tired of my Holly blowing the power valve, so I plan to plug it, and re-jet. I came from Georgia, and now I am in Colorado, PRI jets were 65s, and SEC jets were 68s. Colorado is approx 5500 ft higher that GA. If I plug the power valve, what jets should I go down to. My Holly Jet kit only goes down to 64, but i did get a pair of 62s from a buddy. Maybe 62/65 with power valve plug? Or 64/67s?
Thanks in advance guys.

lukn4trbl

How did you come to the conclusion that the PV is blown?

The Avenger Series (as most modern carbs) has blow out protection.

I don't suggest plugging the power valve if this is a street cruising car.

If you do however, the jets need to increase by 8 sizes on the PV metering
block.

You shuold have more than 67 in the back for a 383 cube motor. Check the
plugs for A/F ratio patterns. I suspect it's too lean for power.

logan_abrams

Well, I am uncertain if the power valve is actually blown, however at idle(when it idles) there is a black film under my exit pipe where it is obvious that it is running way too rich. The car will be driven on the street, and I have heard that Hollys are famous for blowing power valves and letting gas just seep in at idle.

lukn4trbl

It is possible you need to change the power valve to a lower vacuum opening
point.

Stock is 6.5 in./hg.

Do you know your idle manifold vacuum?

logan_abrams

well i dont know the vacuum, but i know it is not alot because of the cam. so should i get idle vacuum and then maybe change out pv? ahh- carbs are simple, yet confusing.

lukn4trbl

No maybe...it's a must!

Carbs are all about pressure. If you don't know where you're at, you can
begin to tune it.