Dart Head Issues
Melting Slicks
Joined: Nov 2004
Posts: 2,715
Likes: 0
From: Tinker till it blows... then back it off a notch, maybe!!
St. Jude Donor '08
After some thought and in agreement with Dart tech, I will be running Cometic C5317-51 gaskets, which are 4.13 bore x .051 thick.
This will drop my CR by a tenth or so as well, which is fine for my application
This will drop my CR by a tenth or so as well, which is fine for my application
Melting Slicks
Joined: Nov 2004
Posts: 2,715
Likes: 0
From: Tinker till it blows... then back it off a notch, maybe!!
St. Jude Donor '08
Originally Posted by vettenuts
Hmmmmm, I didn't want to run the Cometics so it appears I may be out of luck with these heads then.
It looks as though you are leaning towards dumping these heads? Any other issues?
Thread Starter
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Not sure if I can return them, need to discuss with TSP. I think the issues are I wanted to stick with the GM gaskets, have read too much about the Cometics and leaks. Not sure how well the Cometics stand up to street driving either.
The heads look good, but not sure I want to stray too far from my planned approach for this car. The AFR's, my original choice, are likely a better match.
The heads look good, but not sure I want to stray too far from my planned approach for this car. The AFR's, my original choice, are likely a better match.
Supporting Tuner
Joined: Sep 2004
Posts: 51,896
Likes: 39
From: ================== Houston, Texas www.englandgreen.com ================== Necessary Evil™ __________
CI 6-7-8-9-10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14
I have heard the opposite, Bob. In a supercharged/turbocharged application, it's the GM gaskets that leak (under boost) while the Cometic stand up like a champ - both with ARP studs of course.
Can you send me a link or info on where you read about problems with the Cometic?
Thanks
Stephen
Can you send me a link or info on where you read about problems with the Cometic?
Thanks
Stephen
Thread Starter
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Stephen,
Over on LS1Tech there are a number of guys who say they have had problems. I put up a post specifically on this, to see whether it is "operator error". Most who have responded so far love the Cometics so now it is a question of which is the best fit. Per the above, the 4.013 were recommended by Dart, but I have since found a 3.97 and a 3.98 Cometic.
Also heard from Bret Bauer who doesn't think the overlap is a biggy
Over on LS1Tech there are a number of guys who say they have had problems. I put up a post specifically on this, to see whether it is "operator error". Most who have responded so far love the Cometics so now it is a question of which is the best fit. Per the above, the 4.013 were recommended by Dart, but I have since found a 3.97 and a 3.98 Cometic.
Also heard from Bret Bauer who doesn't think the overlap is a biggy
Melting Slicks
Joined: Nov 2004
Posts: 2,715
Likes: 0
From: Tinker till it blows... then back it off a notch, maybe!!
St. Jude Donor '08
It's a bit of a crap shoot.
With chambers at 3.960 or better, if there is any misalignment of chamber or hole in gasket, etc. then a very small portion of the gasket will once again be in the chamber.
You will need perfectly spaced bores, perfectly spaced chambers and perfectly spaced gasket holes, if you want to use 3.97" and maybe even 3.98" gaskets, especially if you clean up the chambers a bit. It is easy to remove .005" just cleaning up.
Even if you had to go with the 4.13" MLS , either Cometic or OEM, you are only looking at a CR change of a tenth or so. IMO, it has become a NON issue.
As to why some people have problems and other don't? Probably warped head or deck of block. You should have a good flat head, just make sure that the block is also OK. Should be checked with mains installed and tight.
With chambers at 3.960 or better, if there is any misalignment of chamber or hole in gasket, etc. then a very small portion of the gasket will once again be in the chamber.
You will need perfectly spaced bores, perfectly spaced chambers and perfectly spaced gasket holes, if you want to use 3.97" and maybe even 3.98" gaskets, especially if you clean up the chambers a bit. It is easy to remove .005" just cleaning up.
Even if you had to go with the 4.13" MLS , either Cometic or OEM, you are only looking at a CR change of a tenth or so. IMO, it has become a NON issue.
As to why some people have problems and other don't? Probably warped head or deck of block. You should have a good flat head, just make sure that the block is also OK. Should be checked with mains installed and tight.
Last edited by RJW; Dec 29, 2005 at 03:24 PM.
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
Mill them to 59cc and make some tq! 
Former Vendor
Joined: Jun 2002
Posts: 2,045
Likes: 3
From: Bridgewater Ma
I've had 50/50 luck with cometics.Now I only use them for special situations. All my FI cars run GM MLS gasket's with boost from 10-20psi.There are some Turbo people pushing 1500rwhp with GM gaskets as well.
Safety Car
Joined: May 2003
Posts: 4,961
Likes: 2
From: Vette-hid.com Lost in DFW texas
Cruise-In V Veteran
Cruise-In VI Veteran
Cruise-In VII Veteran
St. Jude Donor '06-'07
Vette-hid has something in the works with the dart 225 that will be plugnplay coated and hand finished no issues with the rockers and will include the correct gaskets. Dyno numbers will be posted in the next 10 days .
Rocker shafts have to be machined slightly.
Rocker shafts have to be machined slightly.
Last edited by NOT-MEE; Dec 30, 2005 at 05:10 PM.
