Holley question

Myron Piatek · 04-03-2017, 01:06 PM

The amount of jet change needed when blocking off the power valve is determined by the PVCR (power valve channel restriction) - the 2 little holes under the power valve in the metering body. That can be as high as 10. But I never used the formula.

As for using the vacuum reading "at idle, in gear", it's just a reference to make sure that the power valve you start with isn't opening at idle, in gear. If the reading is 7" of vacuum, you'll need a power valve below that to avoid a constant over-rich condition - i.e.: 6.5, 5.5, etc.). It's simply an on/off switch. But as mentioned, it's often eliminated in a race application with success. It's more important in a street application that spends more time idling.

04-03-2017, 01:06 PM	#1
Myron Piatek VIP Member Join Date: Nov 2001 Location: Florida Posts: 1,542 Likes: 34 Liked 138 Times in 51 Posts	Re: Holley question The amount of jet change needed when blocking off the power valve is determined by the PVCR (power valve channel restriction) - the 2 little holes under the power valve in the metering body. That can be as high as 10. But I never used the formula. As for using the vacuum reading "at idle, in gear", it's just a reference to make sure that the power valve you start with isn't opening at idle, in gear. If the reading is 7" of vacuum, you'll need a power valve below that to avoid a constant over-rich condition - i.e.: 6.5, 5.5, etc.). It's simply an on/off switch. But as mentioned, it's often eliminated in a race application with success. It's more important in a street application that spends more time idling. __________________ LOCOMOTION Racing