Holley guys
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Joined: Feb 2005
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Holley guys
Months ago I had an intermittant ignition problem causing some backfiring thru carb...new ignition switch fixed that...yesterday,pulling into driveway,had a quick little backfire thru carb...this after a 30 mile run on freeway...
I'm thinking my power valve is kaput..any thoughts ?
759 Holley/electric fuel pump..
Thanks...
I'm thinking my power valve is kaput..any thoughts ?
759 Holley/electric fuel pump..
Thanks...
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From: Corsicana, Tx
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Yes, new ones have a check valve that limits problems. Been there since like 1992 I believe.
Quickest way to tell if it's blown is to turn idle mixture screws all the way in. If it dies, PV is OK. When they rupture they pull raw fuel through the PV vacuum chamber right into intake. So if you close off idle screws completely and it still runs, then it's likely getting fuel through the blown PV.
JIM
Quickest way to tell if it's blown is to turn idle mixture screws all the way in. If it dies, PV is OK. When they rupture they pull raw fuel through the PV vacuum chamber right into intake. So if you close off idle screws completely and it still runs, then it's likely getting fuel through the blown PV.
JIM
Thread Starter
Race Director
Joined: Feb 2005
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Originally Posted by MILO
The newer holley carbs are suppose to have an anti backfire power valve. How is it running since the backfire?
Pro
Joined: Nov 2004
Posts: 659
Likes: 0
From: Flower Mound Texas
Originally Posted by 427Hotrod
Yes, new ones have a check valve that limits problems. Been there since like 1992 I believe.
Quickest way to tell if it's blown is to turn idle mixture screws all the way in. If it dies, PV is OK. When they rupture they pull raw fuel through the PV vacuum chamber right into intake. So if you close off idle screws completely and it still runs, then it's likely getting fuel through the blown PV.
JIM
Quickest way to tell if it's blown is to turn idle mixture screws all the way in. If it dies, PV is OK. When they rupture they pull raw fuel through the PV vacuum chamber right into intake. So if you close off idle screws completely and it still runs, then it's likely getting fuel through the blown PV.
JIM
Mine is running rich and rough with an occasional backfire. I am pulling 5 - 7" Hg at idle, and I know I'm running the 65 power valves. Going to switch to the 35's this weekend and see if that does the trick.
