Power Valve Plug for Holley
Thread Starter
Drifting
Joined: Jun 2011
Posts: 1,704
Likes: 27
Power Valve Plug for Holley
I think I found out why my holley is running so rich at idle-power valve blown. I've read where you can just put a plug in place of the power valve (Holley even sells them) and just increase the jets a few sizes to compensate. I was wanting to know various opinions on whether this is a good idea or not. Bare in mind I'm kinda a newbie a tuning carbs, I'm really an EFI tuner, but decided to buy this refurbished 4175 (spreadbore) for my '81 if nothing else because I wanted to REALLY learn about carb tuning which was a little before my time.
Thanks
Thanks
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Plugging is not a good idea. The easiest way to determine if your power valve is blown. If you can close the front idle mix screws and your idle quality doesn't change.
Safety Car
Joined: Oct 2000
Posts: 3,593
Likes: 103
From: Southern Indiana
Not a good street idea.
Get someone to put in a power valve protection sleeve.
It won't blow out anymore.
Spectre Performance 2408 - Spectre Performance Power Valve Savers $5.95 out of Summit.
Get someone to put in a power valve protection sleeve.
It won't blow out anymore.
Spectre Performance 2408 - Spectre Performance Power Valve Savers $5.95 out of Summit.
Le Mans Master
Joined: Nov 2008
Posts: 5,691
Likes: 12
From: columbus oh
keep a power valve in your carb for street use
the drill bit is needed to install the blowout protector, comes with instructions
the protector works well in 90% of the time.....good modification.....good luck....
Safety Car
Joined: Oct 2000
Posts: 3,593
Likes: 103
From: Southern Indiana
I don't know, what if someone ask "what are the wheels for on a car"?
But I know on this site someone would have a 6 page scientific explanation.
My answer would be, " don't worry about them they are not important"
But I know on this site someone would have a 6 page scientific explanation.
My answer would be, " don't worry about them they are not important"
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
(Just bustin' your chops, Tim!)Ya know the old saying: Ask a stupid question, get a stupid answer!
Keep it between the ditches!
Scott
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Melting Slicks
Joined: May 2002
Posts: 2,717
Likes: 121
From: Sulphur LA
St. Jude Donor '05-'06,'11,'13-'14,'16,'18,'19,'24, '25
May be getting a little mixed up with terminology here
a ruptured (blown) power valve will allow fuel into the manifold through the carb base.
an open power valve will not allow fuel to flow into the manifold through the base of the carb, the fuel form the open power vale flows through the main well therefore has to be drawn into the manifold by air flow through the carb.
Neal
a ruptured (blown) power valve will allow fuel into the manifold through the carb base.
an open power valve will not allow fuel to flow into the manifold through the base of the carb, the fuel form the open power vale flows through the main well therefore has to be drawn into the manifold by air flow through the carb.
Neal
Melting Slicks
Joined: May 2002
Posts: 2,717
Likes: 121
From: Sulphur LA
St. Jude Donor '05-'06,'11,'13-'14,'16,'18,'19,'24, '25
the info I found on the net indicates that this carb is a single power valve carb with 1 in the primaries and non in the secondaries. You shouldn't plug the valve in the primaries.
Neal
Neal
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
Keep the shiny side up!
Scott
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
May be getting a little mixed up with terminology here
a ruptured (blown) power valve will allow fuel into the manifold through the carb base.
an open power valve will not allow fuel to flow into the manifold through the base of the carb, the fuel form the open power vale flows through the main well therefore has to be drawn into the manifold by air flow through the carb.
Neal
a ruptured (blown) power valve will allow fuel into the manifold through the carb base.
an open power valve will not allow fuel to flow into the manifold through the base of the carb, the fuel form the open power vale flows through the main well therefore has to be drawn into the manifold by air flow through the carb.
Neal
Keep the shiny side up!
Scott
Melting Slicks
Joined: May 2002
Posts: 2,717
Likes: 121
From: Sulphur LA
St. Jude Donor '05-'06,'11,'13-'14,'16,'18,'19,'24, '25
Holy crap, that didn't even occur to me! Never dealt with a blown power valve, figured it would act the same as an open valve, but thinking about it, I see your point and feel a little ashamed for not thinking of it myself. Sorry I shot my mouth off without thinking it through.
Keep the shiny side up!
Scott
Keep the shiny side up!
Scott
Neal
Safety Car
Joined: Oct 2000
Posts: 3,593
Likes: 103
From: Southern Indiana
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
If you choose to buy a kit for the carb, make sure it has the right value power valve in it. Some of the kits I've been getting lately have a set of "generic" parts in them and the power valve has been wrong. They are -usually- stamped.
Thread Starter
Drifting
Joined: Jun 2011
Posts: 1,704
Likes: 27
I'm wondering if it's just not the correct power valve. It has "13" stamped on it, I'm only pulling 10 in of vacuum. If that 13 means 13 inches, the power valve could being held open. Normally I run 15-21" of vacuum, but after installing the holley, only able to get 10", and it runs pig rich, like AFR 10:1, and can't get it any leaner no matter what I do with the idle screws.
Thread Starter
Drifting
Joined: Jun 2011
Posts: 1,704
Likes: 27
