Generation III Internal Engine 1997-2006 LS1 | LS6
Sponsored by:
Sponsored by:

Cometics, .040 or .045?

Thread Tools
 
Search this Thread
 
Old Apr 3, 2007 | 09:15 AM
  #1  
chuckyt1's Avatar
Thread Starter
11 Second Club
iTrader: (33)
 
Joined: Apr 2006
Posts: 1,008
Likes: 0
From: Chicago Area
Default Cometics, .040 or .045?

Going to order my head gaskets today. I was told, by a very reputable sponsor, that .040's on a stock short block would be a little tight. That you would have to be very careful with the .034 quench because of the loose tolerances.

Anyone had any problems with the .040?

The difference between SCR/DCR is 11.4/8.43 for the 040 and 11.25/8.32 with 045. But I've read the the ideal quench is .034.

Any thoughts, comments or suggestions on which ones to use?

Tried searching - all I get is a white screen...
Reply
Old Apr 3, 2007 | 09:17 AM
  #2  
brad8266's Avatar
TECH Senior Member
iTrader: (23)
 
Joined: Aug 2005
Posts: 8,797
Likes: 0
From: Watertown, NY
Default

yeah .040 is a bit tight for a stock block. The .045 would probably be a better choise.
Reply
Old Apr 3, 2007 | 09:50 AM
  #3  
Xtnct00WS6's Avatar
TECH Fanatic
iTrader: (8)
 
Joined: Jan 2005
Posts: 1,429
Likes: 2
From: Sterling VA
Default

I've seen .040 recommended a lot because of the DCR, but I wanted to play it safe and got a .045 and didn't look back. The DCR is a very important element of the combo and I'd think you'll be fine with a .040. However, PTV clearance could become an issue if you have aftermarket valves, and a lot of duration in your cam.
Reply
Old Apr 3, 2007 | 09:52 AM
  #4  
brad8266's Avatar
TECH Senior Member
iTrader: (23)
 
Joined: Aug 2005
Posts: 8,797
Likes: 0
From: Watertown, NY
Default

.040 is more recommended more for the quench not the DCR.
Reply
Old Apr 3, 2007 | 09:55 AM
  #5  
KONG's Avatar
12 Second Club
iTrader: (4)
 
Joined: Oct 2006
Posts: 300
Likes: 0
From: Chesapeake, VA
Default

For an unmilled head the .040 Cometic is perfect. I run them and have no problems.
Reply
Old Apr 3, 2007 | 10:38 AM
  #6  
chuckyt1's Avatar
Thread Starter
11 Second Club
iTrader: (33)
 
Joined: Apr 2006
Posts: 1,008
Likes: 0
From: Chicago Area
Default

PRC LS6 heads milled .030 with 2.02 valves. The dcr only changes by .15 but I was just trying to tighten up the quench a bit.

Think I'll wait for the forged internals, (next winters project), before I get too crazy with it...
Reply
Old Apr 3, 2007 | 11:00 AM
  #7  
PREDATOR-Z's Avatar
TECH Senior Member
 
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
Default

It all depends on you piston to deck clearance.

I have my slugs .010 out and with .050 gaskets = .040 quench, and at 12:1 no issues with misfires or detonnation.

Good range is on average .040 for street.
Reply
Old Apr 3, 2007 | 12:02 PM
  #8  
chuckyt1's Avatar
Thread Starter
11 Second Club
iTrader: (33)
 
Joined: Apr 2006
Posts: 1,008
Likes: 0
From: Chicago Area
Default

.045's it is... Thanks guys
Reply




All times are GMT -5. The time now is 09:09 AM.