Pick one for the brand (GM/Chevy, I assume) and size (cu. in.) engine and configured to fit and connect as your 'plumbing' allows.
pvc valves
Thread Starter
Pro
Joined: Dec 2006
Posts: 665
Likes: 0
From: wilmington nc
pvc valves
I never knew pvc valves were engine specfic, they have numbers or letters on them. Some have straight hose connections an some have a 90 degree bend in them........some have stiff springs in them, some have a weak spring, some have no spring at all. Since the pvc valve is re-introducing burnt gases an water vapor under the base of the carb would that not be like tuneing a vacume leak with a carb, If your not running a stock engine how do you know which pvc valve to use?
Safety Car
Joined: Oct 2007
Posts: 3,729
Likes: 267
From: Austin Texas
Corvette of the Year Winner 2017
2016 C3 of Year Finalist
pick the closest pvc vlave to your application, and plumbing configuration ?
I have always used an orginal PVC even for modified motors.
I have always used an orginal PVC even for modified motors.
Thread Starter
Pro
Joined: Dec 2006
Posts: 665
Likes: 0
From: wilmington nc
Let"s use the 69 as an example here, there were 4 different 427"s
L36 427ci, 390hp Engine
L68 427ci, 400hp Engine
L71 427ci, 435hp Engine
L88 427ci, 430hp Engine
They use different pvc valves. (numbers on the pvc valves are different) Pretty easy so far right, just pick out which engine you have. Unless you have modified one of those engines !
If you put the wrong pvc valve in a engine, an it does not open an close at the right time, would that not affect performance and mileage. If your crankcase is not properly vented, would that not allow gunk build up inside there, not to mention make it prone to oil leaks. One would assume, since those engines have different hp ratings, they also produce different vacume levals.
L36 427ci, 390hp Engine
L68 427ci, 400hp Engine
L71 427ci, 435hp Engine
L88 427ci, 430hp Engine
They use different pvc valves. (numbers on the pvc valves are different) Pretty easy so far right, just pick out which engine you have. Unless you have modified one of those engines !
If you put the wrong pvc valve in a engine, an it does not open an close at the right time, would that not affect performance and mileage. If your crankcase is not properly vented, would that not allow gunk build up inside there, not to mention make it prone to oil leaks. One would assume, since those engines have different hp ratings, they also produce different vacume levals.
Thread Starter
Pro
Joined: Dec 2006
Posts: 665
Likes: 0
From: wilmington nc
I do not have the answer, thats why i ask. Here"s another example
1966 corvette
427 ci 390hp 10.25:1 cr hyd cam, oval port heads, Q-jet carb, uses a pvc valve marked #2
427 ci 425hp 11.00:1 cr solid lifter cam, rect port heads, holley carb, uses a pvc valve marked #6
both have straight vacume line hook ups, seems to me the differance would be the spring tension inside the valve.
In my case, 1974 has 2 different pvc valves listed. one is for a high performance engine, 250hp the other is for non high performance engine 195hp both are 350"s. I now have right at 390 hp what pvc valve would i need? One for a 390hp engine or one for the correct vacume that my engine produces? Thoughts please
I just came from the chevy dealer, for my 74 the non hp valve is marked E, the hp valve is marked K. The high performance valve deffently has a weaker spring in it. I have spoke to several parts people, an so far no one even knew they were marked !
1966 corvette
427 ci 390hp 10.25:1 cr hyd cam, oval port heads, Q-jet carb, uses a pvc valve marked #2
427 ci 425hp 11.00:1 cr solid lifter cam, rect port heads, holley carb, uses a pvc valve marked #6
both have straight vacume line hook ups, seems to me the differance would be the spring tension inside the valve.
In my case, 1974 has 2 different pvc valves listed. one is for a high performance engine, 250hp the other is for non high performance engine 195hp both are 350"s. I now have right at 390 hp what pvc valve would i need? One for a 390hp engine or one for the correct vacume that my engine produces? Thoughts please
I just came from the chevy dealer, for my 74 the non hp valve is marked E, the hp valve is marked K. The high performance valve deffently has a weaker spring in it. I have spoke to several parts people, an so far no one even knew they were marked !
Last edited by dmaaero; Nov 1, 2008 at 12:41 PM. Reason: add
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
5 Best & 5 Worst Corvette Daily Drivers
Joe Kucinski
The Headlights of Every Corvette Generation Explained
Joe Kucinski
5 Best & 5 Most Overrated Corvette Track Packages of All Time!
Joe Kucinski
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
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
Melting Slicks
Joined: Nov 2002
Posts: 2,231
Likes: 7
From: Fort Pierce Florida
