Moparchat - Home of MOPAR enthusiasts worldwide!



Go Back   Moparchat - Home of MOPAR enthusiasts worldwide! > Technical Forums > Performance Talk

Click here to search for Mopar cars and parts for sale.


Reply
 
Thread Tools Display Modes
  #1  
Old 09-09-2009, 01:21 PM
coupe32's Avatar
coupe32 coupe32 is offline
Registered User
 
Join Date: Jan 2003
Location: newburgh in
Posts: 300
Default 340 head gasket thickness

Anyone know what the standard head gasket thickness was on a early 68 340stock engine with X-heads? I think I might have screwed up by using thicker head gaskets after a valve job. I had some gaskets that were in a rebuild package and I believe they were steel fel-pro but I'm not sure. They seemed rather thick to me when I put them on but I didn't even consider compression when I used them.
Anyway I may be taking it apart again this winter. A compression test showed about only 125 to 130 lb in each cylinder. I would think it should be more than that. Im using a racer brown flat tappet cam with I believe 470 lift and 230 duration at .050. Also the heads were surfaced as well as the block to clean everything up. The old Motors Manual says compression should be 180lb for the stock 68 340. The pistons could also be the problem for lower compression as they were replaced with what was supposed to be stock flat top pistons with a bore of .040. The engine runs strong but seems slower since the rebuild. I have been wondering about those head gaskets.
Reply With Quote
  #2  
Old 09-09-2009, 01:48 PM
DJM DJM is offline
Inactive User
 
Join Date: Sep 2008
Location: VC, ND
Posts: 258
Default

Never seen one stock that would pump that kind of pressure.
OEM on that car would have been the steel shim gasket. No longer available for several years. If you can find them use the P4120094 Mopar Pwerformance gasket that is .024-.028 compressed thickness. I don't feel that you are too far out of line withthe gaskets that you are using if you had the heads trued some will take up some of the thickness and are you sure that the engien has never been apart and updated pistons installed in it. IMO be a pretty rare bird to be a virgin.
Reply With Quote
  #3  
Old 09-09-2009, 07:10 PM
dgc333 dgc333 is offline
Inactive User
 
Join Date: Jul 2002
Location: Pembroke, MA
Posts: 773
Default

The difference in compression between the steel shim gasket and the typical 0.040" thick composite gasket is about 0.3:1. Definately not the difference between 130 psi and 180 psi cranking pressure.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
head gasket thickness coupe32 Performance Talk 4 08-16-2007 12:34 AM
head gasket thickness: zlfanatic Performance Talk 7 05-28-2003 08:18 PM
Head gasket thickness cushmanr Performance Talk 4 11-05-2001 07:43 PM
production head gasket thickness? shannon Performance Talk 3 06-26-2001 12:24 AM
Head gasket thickness Squad Performance Talk 5 01-07-2000 10:59 AM




All times are GMT -4. The time now is 11:11 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
. . . . .