pcv
Team Owner
Joined: Jun 2000
Posts: 38,923
Likes: 1,481
From: Southbound
Cruise-In II Veteran
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
The PCV valve output is oil vapors from the crankcase of your engine. If you have a fuel vapor canister and it is "T"-ed into the PCV output hose, then both oil and fuel vapors get fed into the baseplate of the carb.
You can tie that PCV output into the front or back of the carb's baseplate, BUT (as mentioned above) if you also have power brakes and they are fed from the rear of the carb baseplate, you run the risk of oil/fuel vapors getting into the power brake diaphragm and having it deteriorate from those fumes. So, while that hose arrangement may "work", it is not such a good idea to tie the PCV output and power brake vacuum supply hose together.
You can tie that PCV output into the front or back of the carb's baseplate, BUT (as mentioned above) if you also have power brakes and they are fed from the rear of the carb baseplate, you run the risk of oil/fuel vapors getting into the power brake diaphragm and having it deteriorate from those fumes. So, while that hose arrangement may "work", it is not such a good idea to tie the PCV output and power brake vacuum supply hose together.
Thread Starter
3rd Gear
Joined: Nov 2012
Posts: 3
Likes: 0
pcv valve hose
My power brake booster hose is tied in to a plug on the hi-rise aluminum intake leaving only the pcv hose on the back of carb.Will this make me lose some vacuum to ohter things like my headlights?Is it bad to have oil from the pcv getting into my carb?
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
It all depends what carb you have.
If it's a qjet, then any pcv connection (3/8" tube) will be at the front.
If it's a Holley, some are near the rear.
The important part is that the channels in the baseplate disperse the vapors as evenly as possible to all the cylinders. Check your carb to make sure it does not just go to one cylinder. The brake booster is fine going just to one.
If it's a qjet, then any pcv connection (3/8" tube) will be at the front.
If it's a Holley, some are near the rear.
The important part is that the channels in the baseplate disperse the vapors as evenly as possible to all the cylinders. Check your carb to make sure it does not just go to one cylinder. The brake booster is fine going just to one.
Race Director
Joined: Apr 2000
Posts: 17,672
Likes: 199
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
It doesn't matter if the PCV line is connected to the front or to the rear of the carb (at the baseplate). Both are "manifold" vacuum connections and both are large enough to handle the PCV output. But, it is best if the PCV line is the only line at its connection point.