L82 burning through Header Gaskets
Thread Starter
Intermediate
Joined: Jul 2020
Posts: 47
Likes: 7
L82 burning through Header Gaskets
Good evening all!
I blew out the first set of header gaskets about 4 weeks into ownership and now, about another 4 weeks and only 400 or so miles later, the passenger side gasket has given way somewhere again. They're not expensive, just a bit of a pain and time consuming if it's gonna happen once a month. I know headers are bad on gaskets, especially on the 350s with the really close exhaust ports, but should it be this bad? What could I be doing wrong here? Over torquing the header bolts maybe? Is there a preferred gasket brand/type? Also I have Vortec heads.
Thanks!
I blew out the first set of header gaskets about 4 weeks into ownership and now, about another 4 weeks and only 400 or so miles later, the passenger side gasket has given way somewhere again. They're not expensive, just a bit of a pain and time consuming if it's gonna happen once a month. I know headers are bad on gaskets, especially on the 350s with the really close exhaust ports, but should it be this bad? What could I be doing wrong here? Over torquing the header bolts maybe? Is there a preferred gasket brand/type? Also I have Vortec heads.
Thanks!
Thread Starter
Intermediate
Joined: Jul 2020
Posts: 47
Likes: 7
Oh, one more thing. The vacuum advance is not currently hooked up on my distributor. I plane on fixing this. However, could this be contributing to the gasket problem? Maybe running a bit richer than it should therefore backfiring more/more aggressively therefore causing undo pressure and stress on the gaskets? Just a thought, thanks
Burning Brakes
Joined: Jun 2020
Posts: 881
Likes: 113
perhaps timing is too retarded and burning late; burning in the exhaust ports and primaries
1 get Lars' timing white papers
2 verify timing mark on damper hasn't slipped: verify when #1 piston is at true TDC the damper is at Zero.
3 reconnect vacuum advance
1 get Lars' timing white papers
2 verify timing mark on damper hasn't slipped: verify when #1 piston is at true TDC the damper is at Zero.
3 reconnect vacuum advance
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,105
Likes: 9,236
From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
Try the aluminum gaskets. I like the Mr Gasket gaskets.I tried Perceys but they are super thin at the sides where the bolts go through the header. I also use the copper gasket sealant and this is the first time I havent had to deal with them. And find a locking header bolt you like. I had to use longer bolts for my setup so I bought allen head bolts with saftey wire holes and safety wired them. None of them are loose and the gaskets are still going strong.
Thread Starter
Intermediate
Joined: Jul 2020
Posts: 47
Likes: 7
Thank you. I sent Lars an email requesting the timing papers. I've read a few of his things before and they seem very in depth so I'm sure this will cover all I need to know. However, I have not messed with timing before and I am not too sure on the best way to go about it. What is the least intrusive/involved method for determining TDC of the #1 piston? And vacuum advance will happen this weekend.
Thread Starter
Intermediate
Joined: Jul 2020
Posts: 47
Likes: 7
Try the aluminum gaskets. I like the Mr Gasket gaskets.I tried Perceys but they are super thin at the sides where the bolts go through the header. I also use the copper gasket sealant and this is the first time I havent had to deal with them. And find a locking header bolt you like. I had to use longer bolts for my setup so I bought allen head bolts with saftey wire holes and safety wired them. None of them are loose and the gaskets are still going strong.
Le Mans Master
Joined: Mar 2006
Posts: 5,775
Likes: 585
From: Texas
Had the same problem years ago. Turned out the header flange wasn't flat. I had a machinist take about 50 thousandths off the flange and it fixed the problem. If the aluminum gaskets don't fix the problem, might want to get the header flange checked for flatness.
This is a good video of a machinist dealing with a bad header flange:
This is a good video of a machinist dealing with a bad header flange:
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
Next time you pull the headers back off, insert one header bolt into the head and bottom it out by hand. Measure the distance between cyl head & under the bolt head.
If that distance is greater than the thickness of the flange . . guess what . . . . .
I have not had any issues with Percys aluminum. They fill in any imperfections the the head flange often has. Great quality.
You may want to run a file down the inside of the flange looking for high spots, burrs, poor welds.
There is a huge difference between a $19.99 set of gaskets and $40 gaskets. Spend the extra $$$.
If you suspect the flange has a warping issue, make two kerf cuts on the back side of the flange (towards the head). A kerf cut is a shallow cut that allows the flange to twist, lay flat and straighten out when the bolts are torqued to spec. Make the kerfs between cyl 1 & 3 plus 5 & 7. Then do the other bank. A hacksaw blade works well for this task. Once the gasket is in place, the kerf becomes invisible.
If that distance is greater than the thickness of the flange . . guess what . . . . .
I have not had any issues with Percys aluminum. They fill in any imperfections the the head flange often has. Great quality.
You may want to run a file down the inside of the flange looking for high spots, burrs, poor welds.
There is a huge difference between a $19.99 set of gaskets and $40 gaskets. Spend the extra $$$.
If you suspect the flange has a warping issue, make two kerf cuts on the back side of the flange (towards the head). A kerf cut is a shallow cut that allows the flange to twist, lay flat and straighten out when the bolts are torqued to spec. Make the kerfs between cyl 1 & 3 plus 5 & 7. Then do the other bank. A hacksaw blade works well for this task. Once the gasket is in place, the kerf becomes invisible.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
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
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
Burning Brakes
Joined: Jun 2020
Posts: 881
Likes: 113
Thank you. I sent Lars an email requesting the timing papers. I've read a few of his things before and they seem very in depth so I'm sure this will cover all I need to know. However, I have not messed with timing before and I am not too sure on the best way to go about it. What is the least intrusive/involved method for determining TDC of the #1 piston? And vacuum advance will happen this weekend.
https://www.summitracing.com/parts/crn-99412-1
and you mark the OD of your DAMPER & split the difference per these instructions; simple job but pay attention to detail.
https://static.summitracing.com/glob...sum-900189.pdf
the "split" may be exactly where your timing groove is currently on damper;
but old dampers slip and if you above Verification "split" occurs other than groove, you can be sure the damper needs replacement.
If you set timing via an incorrect groove location, the timing job will be crap.