squaring and trueing the deck Tolerance - LS1TECH - Camaro and Firebird Forum Discussion



Generation IV Internal Engine 2005-2014 LS2 | LS3 | LS7 | L92 | LS9

squaring and trueing the deck Tolerance

Reply
 
Thread Tools Search this Thread
Old 03-14-2017, 01:02 PM   #1
Launching!
Thread Starter
iTrader: (8)
 
Join Date: Oct 2004
Location: NJ/AZ
Posts: 291
Default squaring and trueing the deck Tolerance

Machine shop trued and squared the deck, what is the standard tolerance they should be held to? Just measured piston to deck surface front to back we are getting .006 difference, was not expecting to see that much of a difference. The crank was also reground due to spun 1+2 rod bearings, two new rods installed. I'm guessing that's were the problem lies since the other cylinders are true and square. Thoughts ??

1+2= .008
3+4= .003
5+6= .002
7+8= .002
Smo's04Gto is offline   Reply With Quote
Old 03-14-2017, 01:23 PM   #2
KCS
Moderator
iTrader: (19)
 
KCS's Avatar
 
Join Date: Mar 2005
Location: Conroe, TX
Posts: 7,614
Default

That seems odd to be out that much up front. How are you checking the piston protrusion?

It's not hard to get it within +/-.002", but sometimes you're battling tolerances in the crank, rods, and even piston machining.
KCS is offline   Reply With Quote
Old 03-14-2017, 03:46 PM   #3
Launching!
Thread Starter
iTrader: (8)
 
Join Date: Oct 2004
Location: NJ/AZ
Posts: 291
Default

Depth Mic, squaring up piston every 90 degree's till the piston is parallel to deck.
.006 seems like a lot for stack up tolerance piston, rods.
Smo's04Gto is offline   Reply With Quote
Old 03-14-2017, 07:53 PM   #4
KCS
Moderator
iTrader: (19)
 
KCS's Avatar
 
Join Date: Mar 2005
Location: Conroe, TX
Posts: 7,614
Default

Quote:
Originally Posted by Smo's04Gto View Post
Depth Mic, squaring up piston every 90 degree's till the piston is parallel to deck.
.006 seems like a lot for stack up tolerance piston, rods.
I agree but usually any difference from one end to the other is more linear. Going from .003" to .008" so abruptly isn't normal. I'd say the problem lies in whatever was done to repair the #1 and 2 rod journals.
KCS is offline   Reply With Quote
Old 03-15-2017, 10:45 AM   #5
Launching!
Thread Starter
iTrader: (8)
 
Join Date: Oct 2004
Location: NJ/AZ
Posts: 291
Default

KCS, trying to get the details on the crank now. All I know at this point is all the rods and mains are .010 under.
Smo's04Gto is offline   Reply With Quote
Old 03-15-2017, 10:59 AM   #6
KCS
Moderator
iTrader: (19)
 
KCS's Avatar
 
Join Date: Mar 2005
Location: Conroe, TX
Posts: 7,614
Default

I replied in your YB thread too.

I think checking the piston position at BDC might answer some questions too. If the crank grinder was out a little more on that rod journal to fix the damage, then you may have a little more stroke just on those two cylinders. If it is in the rods and pistons, then stroke would be the same.
KCS is offline   Reply With Quote
Old 03-15-2017, 12:08 PM   #7
Launching!
Thread Starter
iTrader: (8)
 
Join Date: Oct 2004
Location: NJ/AZ
Posts: 291
Default

Thanks for your input, great idea on checking stroke/crank swing without pulling it a part.

Quote from builder.

Cranks was magnafluxed and checked for cracks, none found. The Crank journals were ground .010 to clean up the spun bearing.

I have never seen an engine with all pistons sticking out of the hole exactly the same. These are normal variances that all blueprinted engines have
Smo's04Gto is offline   Reply With Quote
Old 03-15-2017, 12:52 PM   #8
KCS
Moderator
iTrader: (19)
 
KCS's Avatar
 
Join Date: Mar 2005
Location: Conroe, TX
Posts: 7,614
Default

Quote:
Originally Posted by Smo's04Gto View Post
Thanks for your input, great idea on checking stroke/crank swing without pulling it a part.

Quote from builder.

Cranks was magnafluxed and checked for cracks, none found. The Crank journals were ground .010 to clean up the spun bearing.

I have never seen an engine with all pistons sticking out of the hole exactly the same. These are normal variances that all blueprinted engines have
Man, that's kind of a shitty response. Like I said earlier, it's not hard to get within +/- .002" and any worse is than that is sloppy IMO. When it's almost dead nuts the same in all cylinders except for just those two, that should be a red flag that something was off. It's not something that is going to make or break the whole build, but it's a good indicator of their quality policies/customer service.
KCS is offline   Reply With Quote
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
F.s. Brand new -rhs- lsx short block Birddogg Parts Classifieds 3 09-24-2017 11:55 AM
Effect Of Quench On Detonation Question 97 6speed z LT1-LT4 Modifications 40 01-07-2017 11:16 PM
Engine builder says it's ok that the liners are above EXPERTS INSIDE PLZ! C6smackdown Generation IV Internal Engine 16 07-08-2016 11:31 PM
Forged Lq4 Adam Hudson Parts Classifieds 4 06-30-2016 11:10 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 09:04 PM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: