GN and T-Type Performance Enthusiasts (GNTTYPE) Forums GN and T-Type Performance Enthusiasts (GNTTYPE) Forums
This is a general site search and does not include list archives.

Go Back   GN and T-Type Performance Enthusiasts (GNTTYPE) Forums > Technical Topics > Engine Mechanical

Reply
 
Thread Tools Display Modes
  #1  
Old 03-30-2005, 09:42 PM
BH-84 TType BH-84 TType is offline
 
Join Date: Mar 2005
Posts: 2
BH-84 TType is on a distinguished road
Default Engine rebuild help (specificatons)

I am currently rebuilding a '84 TType engine. Installed the new crank main bearings, torqued them down, removed one cap at a time to check the main bearing oil clearance w/plastic gage and it measured 0.002" to 0.0022" across the 4 bearings. My Chilton's and Haynes manuals call out 0.0003"-0.0018" for mains (and 0.0005"-0.0026" for rods). I took the bearings back to the NAPA parts dealer and their Clevite 77 bearing manual calls out 0.0005"-0.0034" for mains (and 0.001"-0.0037" for rods). Which specifications are correct? What concerns are there if I was to use the 0.002" to 0.0022" clearance bearings? My goal is to get 100K+ miles out of this rebuild. p.s. I am also installing a high volume oil pump kit.
Reply With Quote
  #2  
Old 03-31-2005, 11:42 AM
pfredricks's Avatar
pfredricks pfredricks is offline
Administrator
 
Join Date: Aug 2004
Location: Illinois
Posts: 244
pfredricks is on a distinguished road
Send a message via AIM to pfredricks
Lightbulb Re: Engine rebuild help (specificatons)

My 1984 GM factory service manual states clearances that match what you quote from your Chilton's manual: Mains = .0003-.0018 Rods = 0.0005-.0026.

Jack Merkel (http://www.merkelengines.com/) writes: "…we recommend main bearing clearance of .0015” - .002” (.0015” preferred) and rod bearing clearance of .0018” - .002” (.0018 preferred)."

I'm going with Jack's recommendation on my rebuild since I expect infrequent racing use and mostly street driving.
__________________

Paul Fredricks
pfredricks@gnttype.org
Reply With Quote
  #3  
Old 04-01-2005, 04:07 PM
BH-84 TType BH-84 TType is offline
 
Join Date: Mar 2005
Posts: 2
BH-84 TType is on a distinguished road
Default Re: Engine rebuild help (specificatons)

Thanks for the input- the tighter specification sounds better to me as well! I guess I will have to work this out with the parts dealer.
Reply With Quote
  #4  
Old 04-01-2005, 07:56 PM
arthdgls arthdgls is offline
New Member
 
Join Date: Mar 2005
Location: Ga
Posts: 12
arthdgls is on a distinguished road
Default Re: Engine rebuild help (specificatons)

Im also in the middle of a rebuild. I spoke with Jack Merkel personally and he says things have changed since federal mogul now offers 3/4 oil groove main bearings. Also make sure you go with the wider rod bearing. Part # 6-3755APA are 10% wider than stock. The updated clearences if I remember correctly are .0018 to .0022 .002 prefered mains . 0015 to .0022 rods with .0018 stiil being an excellent choice for a hot street engine . All out race motors go with the looser of the specs . Good luck and let me know how things turn out. Doug Conyer 1985 WH1

Last edited by arthdgls; 04-01-2005 at 08:16 PM.
Reply With Quote
Reply

Bookmarks

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


All times are GMT -4. The time now is 02:28 AM.


This page maintained by: gnttype-webmaster@gnttype.org

The content, images, text and multimedia displayed and contributed by the members of the Grand National and T-Type Performance Enthusiasts Organization are Copyright ©1996-2005. No part, section, image, article or whole of this site may be reposted or redisplayed without permission of the author/contributor and/or the Grand National and T-Type Performance Enthusiasts Organization.

Powered by vBulletin® Version 3.7.3
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.