Vented, non-vented gas cap
Thread Starter
Drifting
Joined: Jun 2005
Posts: 1,950
Likes: 498
From: Chino Hills CA
Vented, non-vented gas cap
Can youn take a non vented gas cap and make it vented by drilling a tiny hole in it? If so, is there a specific place to drill the hole? I want to plug the cannister hose.
Instructor
Joined: Sep 2005
Posts: 241
Likes: 0
From: St Louis Missouri
On my 75 I just went through this. I bought a “vented” cap from Autozone. I ran the car for a while before it died. I finally cracked the tank cap and THUD the tank took a bunch of air in. I was able to take the internals out of the cap because there was a one way valve that let hot fumes out, but no air in. Now it runs great.
Melting Slicks
Joined: Mar 2005
Posts: 2,838
Likes: 10
From: Austin TX
A 'vented' cap will allow air "in" to replace spent fuel. It will not (or shouldn't) allow fumes or fuel "out".
Some cars had a closed system which utilized the charcoal cansiter and the correct gas cap is a 'non-vented' cap.
If the charcoal set-up has been removed or you have a pre-1971 (I think) car you'll need a 'vented' cap.
I wouldn't drill a hole into your gas cap,..you'll have a fuel leak, smell, and possible safety issues.
Some cars had a closed system which utilized the charcoal cansiter and the correct gas cap is a 'non-vented' cap.
If the charcoal set-up has been removed or you have a pre-1971 (I think) car you'll need a 'vented' cap.
I wouldn't drill a hole into your gas cap,..you'll have a fuel leak, smell, and possible safety issues.
Melting Slicks
Joined: May 2003
Posts: 2,387
Likes: 2
From: Meriden CT
dont drill it, you'll risk a fuel leak. There was just a long thread about this topic.... I do believe that some vented caps only vent OUT, releasing extra pressure. Buildup of vacuum in the tank is supposed to be released through the air/fuel serparator adn charcoal canister. My vented cap does not releive the vacuum in the tank, only pressure.
Racer
Joined: Apr 2005
Posts: 494
Likes: 0
From: Virginia
Originally Posted by Hauq`
I bought a “vented” cap from Autozone. I ran the car for a while before it died. I finally cracked the tank cap and THUD the tank took a bunch of air in. I was able to take the internals out of the cap because there was a one way valve that let hot fumes out, but no air in. Now it runs great.
Drifting
Joined: Feb 2005
Posts: 1,438
Likes: 2
From: Melrose Florida
I drilled a hole through the sealed cap for the '74 donor tank for my '69. I think I used 1/8" drill bit, right through the middle.
I've done the same thing for my street rod.
No gas leaks, no vapor lock, no problem.
I've done the same thing for my street rod.
No gas leaks, no vapor lock, no problem.
Le Mans Master
Joined: Mar 1999
Posts: 6,744
Likes: 1
From: delmont pa
Cruise-In I Veteran
Cruise-In II Veteran
Originally Posted by halfmoontrail
I drilled a hole through the sealed cap for the '74 donor tank for my '69. I think I used 1/8" drill bit, right through the middle.
I've done the same thing for my street rod.
No gas leaks, no vapor lock, no problem.
I've done the same thing for my street rod.
No gas leaks, no vapor lock, no problem.
Pro
Joined: Jun 2005
Posts: 581
Likes: 60
From: USA
I've been drilling 1/16" holes in my gas caps for over 10 years now, never a problem. I always have to do this when I disconnect the "Evaporative Emissions Canister" also known as the charcoal canister. Drilled the hole in the center or any other convenient place. no leaks, done it for my 4x4, vettes, and other normal cars.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
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
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
Burning Brakes
Joined: Aug 2005
Posts: 1,126
Likes: 0
From: Hudson Falls, N.Y. 76 Vette Modified L-48
Originally Posted by halfmoontrail
I drilled a hole through the sealed cap for the '74 donor tank for my '69. I think I used 1/8" drill bit, right through the middle.
I've done the same thing for my street rod.
No gas leaks, no vapor lock, no problem.
I've done the same thing for my street rod.
No gas leaks, no vapor lock, no problem.
I did the same thing on the 76, same results....I expect if I roll the damn thing, it'll leak, but that's NOT in the game plan...
Instructor
Joined: Sep 2005
Posts: 241
Likes: 0
From: St Louis Missouri
Originally Posted by edheinrich
Removing my canister too and plugging the return line. Is this the best solution to this problem?