BBC and CRAZY VAcuum system???
Thread Starter
Burning Brakes
Joined: Aug 2008
Posts: 845
Likes: 12
From: LAKE BARRINGTON IL
BBC and CRAZY VAcuum system???
Hi all!,
FInishing up my build on 69 vette vert, 454 ~500 HP, 4 speed....and replaced the canister on pass side engine bay. also did the couple valves on drivers side.
I am wondering if my cam...about a .620 lift is too big-robbing the system.
the sucky part is that the lights will just come up under HARD/FUN
acceleration....
ideas?
thanks!
R
FInishing up my build on 69 vette vert, 454 ~500 HP, 4 speed....and replaced the canister on pass side engine bay. also did the couple valves on drivers side.
I am wondering if my cam...about a .620 lift is too big-robbing the system.
the sucky part is that the lights will just come up under HARD/FUN
acceleration....
ideas?
thanks!
R
Le Mans Master
Joined: Aug 2006
Posts: 7,426
Likes: 1,559
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Something is wrong with that.
Your engine produces the least vacuum on acceleration.
You have the highest vacuum when you let up on the gas.
You have the highest vacuum when you let up on the gas.
Le Mans Master
Joined: Aug 2006
Posts: 7,426
Likes: 1,559
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
Yep, your zinc 3-nipple check valve is probably not holding vacuum as it should so under hard acceleration your headlights are defaulting to the open position.
Thread Starter
Burning Brakes
Joined: Aug 2008
Posts: 845
Likes: 12
From: LAKE BARRINGTON IL
Thanks all!!! Good info!
Will hopefully get vacuum gauge in this weekend.
Actually replaced that metal 1to2 valve in restoration. So it's new.
Should not be the issue.
Will post back this weekend!
So got a bet for 13...so far...
Where does it have to be for proper working of headlights/wiper door?
Thanks!
Will hopefully get vacuum gauge in this weekend.
Actually replaced that metal 1to2 valve in restoration. So it's new.
Should not be the issue.
Will post back this weekend!
So got a bet for 13...so far...
Where does it have to be for proper working of headlights/wiper door?
Thanks!
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
Safety Car
Joined: Oct 2007
Posts: 3,729
Likes: 267
From: Austin Texas
Corvette of the Year Winner 2017
2016 C3 of Year Finalist
isolate remove all vacuum connections anything above 10" should be sufficient.
you most likely have leaks, compare base vacuum with vacuum reading with everything connected. if you have leaks isolate using the vacuum gauge.
you most likely have leaks, compare base vacuum with vacuum reading with everything connected. if you have leaks isolate using the vacuum gauge.
Thread Starter
Burning Brakes
Joined: Aug 2008
Posts: 845
Likes: 12
From: LAKE BARRINGTON IL
Will look into!
Thanks...should have a gauge on saturday.
HAD a buddy mechanic of mine say I would need a vacuum pump...b/c of all systems AND power brake booster too...
Thanks!
Thanks...should have a gauge on saturday.
HAD a buddy mechanic of mine say I would need a vacuum pump...b/c of all systems AND power brake booster too...
Thanks!