Will cometic head gaskets leak coolant ??
Thread Starter
Melting Slicks
Joined: Sep 2007
Posts: 2,597
Likes: 3
From: READING PA
St. Jude Donor '08-'09-'10
Will cometic head gaskets leak coolant ??
Just had a discussion w Engine Builder about using the TF 225's I'm ordering w 61cc chambers using a .040 COMEDIC to achieve a CR of
around 11.5: 1. He said absolutly not. They will leak coolant in a short time and insisted the .051 OEM is the way to go w/o ARP Head bolts.
I was stunned at this because I thaught optimal QUENCH area was what
would be needed to get the most out of my setup w a 232 CAM currently
yielding 461 RWHP and looking to get to 500 RWHP employing the TF'S.
Are there any members having coolant leaks or other problems with the COMEDICS. Where am I going wrong ?
around 11.5: 1. He said absolutly not. They will leak coolant in a short time and insisted the .051 OEM is the way to go w/o ARP Head bolts.
I was stunned at this because I thaught optimal QUENCH area was what
would be needed to get the most out of my setup w a 232 CAM currently
yielding 461 RWHP and looking to get to 500 RWHP employing the TF'S.
Are there any members having coolant leaks or other problems with the COMEDICS. Where am I going wrong ?
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
I've never not used them and I never had a leak.
If his last try with them was a long time ago, he is out of date on info. He may also have used them on a non-ls engine and they may have had irregular deck surfaces. Many inferior mills on heads would have grooves that can cause leaks. Trick Flows are not bad mills.
If his last try with them was a long time ago, he is out of date on info. He may also have used them on a non-ls engine and they may have had irregular deck surfaces. Many inferior mills on heads would have grooves that can cause leaks. Trick Flows are not bad mills.
Last edited by SpinMonster; Jan 12, 2010 at 12:10 PM.
Thread Starter
Melting Slicks
Joined: Sep 2007
Posts: 2,597
Likes: 3
From: READING PA
St. Jude Donor '08-'09-'10
I've never not used them and I never had a leak.
If his last try with them was a long time ago, he is out of date on info. He may also have used them on a non-ls engine and they may have had irregular deck surfaces. Many inferior mills on heads would have grooves that can cause leaks. Trick Flows are not bad mills.
If his last try with them was a long time ago, he is out of date on info. He may also have used them on a non-ls engine and they may have had irregular deck surfaces. Many inferior mills on heads would have grooves that can cause leaks. Trick Flows are not bad mills.
said I would be lucky to see 435RWHP. A good MECHANIC but not a DYNOTUNER .
AM I on target using 61CC TF's w .040 COMEDIC to arrive at a CR of 11.5 ?
Premium Supporting Vendor
Joined: Oct 2004
Posts: 23,599
Likes: 1,225
From: Providing the most proven supercharger kits for your C5/6/7 609-752-0321
I have seen a few external leaks from Cometic gaskets and stopped using them, it was a while ago though, maybe they rectified the problem now. Good luck on your build! 
Thread Starter
Melting Slicks
Joined: Sep 2007
Posts: 2,597
Likes: 3
From: READING PA
St. Jude Donor '08-'09-'10
Melting Slicks
Joined: Sep 2004
Posts: 3,439
Likes: 105
From: Northern Colorado
I had a Cometic head gasket leak on my LS7. Gaskets were .51 thickness and we used ARPhead studs.
BUT
I later found out that my #4 liner ( Darton resleaved block) had dropped .001" allowing combusting gas's into my coolant system.
Took me 3 head gasket swaps to find it out.
The last swap we used stock GM gaskets.
If you compare the two side by side the stockers appear to have more material on them. If you do not need a thinner gasket..I'd stay stock.
Also remember, if you use any fastener than stock on the heads, you "should" be doing your final hone using those fasteners.
I now use ARP head stauds and STOCK GM gaskets with a 65CC combustion chamber on my latest build.
good luck.
BUT
I later found out that my #4 liner ( Darton resleaved block) had dropped .001" allowing combusting gas's into my coolant system.
Took me 3 head gasket swaps to find it out.
The last swap we used stock GM gaskets.If you compare the two side by side the stockers appear to have more material on them. If you do not need a thinner gasket..I'd stay stock.
Also remember, if you use any fastener than stock on the heads, you "should" be doing your final hone using those fasteners.
I now use ARP head stauds and STOCK GM gaskets with a 65CC combustion chamber on my latest build.
good luck.
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
Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
A lot of the issues concerning leaks with Cometic gaskets is not with the gaskets themselves but with block and head surface preparation. If the surfaces are not righ then you can incur leaks. For extra insurance I always copper coat the gaskets even though Cometic says no sealants are to be used with their gaskets, doing this and insuring that the surface prep is correct I have never had one leak. Except once when a customer supplied a set of ARP bolts that worked loose because they were not retorqued after a few heat cylcles.
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
I never heard of anyone having leaks with comedics. I do believe it was a while back when he came to that conclusion and those things stay in the brain. BTW the builder did not think the 232 cam was a good choice and
said I would be lucky to see 435RWHP. A good MECHANIC but not a DYNOTUNER .
AM I on target using 61CC TF's w .040 COMEDIC to arrive at a CR of 11.5 ?
said I would be lucky to see 435RWHP. A good MECHANIC but not a DYNOTUNER .
AM I on target using 61CC TF's w .040 COMEDIC to arrive at a CR of 11.5 ?
A 232 cam (not optimum) will make about 490rwhp with trick flow225's and a FAST. A 234 cam I have will break 500rwhp (closer to 510rwhp)
A 232 cam makes near 455rw with a FAST without changing heads.
Advanced
Joined: Nov 2006
Posts: 93
Likes: 0
From: Waukesha WI
Safety Car
Joined: Jan 2006
Posts: 4,598
Likes: 78
From: Miami FL
2020 C6 of the Year Finalist - Unmodified
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15-'16,'17,'18-'19-'20-'21-'22
I am running 62cc Livernois Stage 3 243 heads with 0.036" Cometic gaskets on a stock LS2 short block for 11.7 to 1 static CR. New GM head bolts. No leaks, and lots of fun with a tiny 224*/228* 0.595" cam.
Platinum Supporting Vendor
Joined: Sep 2001
Posts: 3,665
Likes: 341
We chased a loss of coolant for 3 months back and forth. It was a very small amount, but over time it all adds up. The motor was built by CRD and block and heads had a better finish then stock. It ended up being the Cometic gaskets. I talked to Cometic about it and they said they have never heard of an issue. The motor went back together with factory gaskets. I will say this, it didn't leak until the motor had about 7500 miles on it. I was on the fence about trying them again, and to be honest I will probably put them on my car and try but not on a customers.
Melting Slicks
Joined: Mar 2003
Posts: 3,116
Likes: 10
From: Macomb MI
Phil
Thread Starter
Melting Slicks
Joined: Sep 2007
Posts: 2,597
Likes: 3
From: READING PA
St. Jude Donor '08-'09-'10
They have revised their gaskets numerous times (Gee wonder why) in the past 5 years and IMHO they still SUCK! I as well quit using them due to numerous issues with coolant. I had a customer supply his own parts (may 09) and insisted to use them with his "Package". Well 5 months later I got the phone call needing a coolant issue resolved. Its a Dam shame when something that 3x+ the cost doesnt perform as well as the OEM.
Phil
Phil
Thread Starter
Melting Slicks
Joined: Sep 2007
Posts: 2,597
Likes: 3
From: READING PA
St. Jude Donor '08-'09-'10
to being optimal for a cam with zero issues with tons of torque for a DD.
I will only know if I can reach 500 buy putting the trick flows on and the tractionmonster TIRE & WHEEL setup , make a trip to the DYNO then straight to the track for that 129 mph run. Thanks for your input as I work out the final details on the Heads & Gasket combo.
Tech Contributor
Joined: Jul 2002
Posts: 14,950
Likes: 264
From: St. Louis, MO
St. Jude Donor '08
23,000 miles and 2.5 daily driving years and 250 drag strip runs on my cometics, no problems. My shop uses them all the time and I've never heard of any problems.
I want Trick Flows myself, but the price is close to a Grand Sport Wide body kit and I can't decide.
Good thing I don't have the money for either! 
Plus I'm afraid my beloved stock clutch might meet its match if I upgraded my heads.
I want Trick Flows myself, but the price is close to a Grand Sport Wide body kit and I can't decide.
Good thing I don't have the money for either! Plus I'm afraid my beloved stock clutch might meet its match if I upgraded my heads.
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
Guy, I know the 232 Cam is not optimal for peak numbers but it is close
to being optimal for a cam with zero issues with tons of torque for a DD.
I will only know if I can reach 500 buy putting the trick flows on and the tractionmonster TIRE & WHEEL setup , make a trip to the DYNO then straight to the track for that 129 mph run. Thanks for your input as I work out the final details on the Heads & Gasket combo.
to being optimal for a cam with zero issues with tons of torque for a DD.
I will only know if I can reach 500 buy putting the trick flows on and the tractionmonster TIRE & WHEEL setup , make a trip to the DYNO then straight to the track for that 129 mph run. Thanks for your input as I work out the final details on the Heads & Gasket combo.
