Gm piston number what does it mean - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Hotrodding Basics
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 02-03-2013, 05:54 AM
Registered User
 
Join Date: Apr 2011
Location: new hampshire
Posts: 31
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Gm piston number what does it mean

I have a gm piston. just try to figure out what the numbers on the bottom of the piston means 3991476 60 thanks.

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 02-03-2013, 09:13 AM
vinniekq2's Avatar
Registered User
 
Join Date: Jun 2012
Location: BC,Canada
Age: 56
Posts: 7,714
Wiki Edits: 0

Thanks: 309
Thanked 744 Times in 715 Posts
contact fbird88 I think he has used these pistons
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 02-03-2013, 12:26 PM
BigEd36's Avatar
Registered User
 
Last photo:
Join Date: Nov 2009
Location: Auburn, IN
Age: 65
Posts: 386
Wiki Edits: 0

Thanks: 17
Thanked 43 Times in 39 Posts
From searching online I can't find much about that casting number, but Silvolite shows a piston replacing that part number, it's either 11 or 13 cc dish piston, Silvolite's version is 1.54 compression height instead of the factory 1.56 so they would be considered "rebuilder" pistons that will give you .020" more "in the hole" or piston deck height than standard pistons. The 60 at the end of the number probably means they're .060" overbore sized.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 02-03-2013, 01:33 PM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 59
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 597 Times in 546 Posts
I'd tend to agree w/BigEd36- Silvolite Pistons, bottom of the page. Two possibilities are shown, one has a 0.070" deep dish, the other a 0.080" dish. Both are available 0.060" over. The numbers shows up under "O.E. Casting No."

If these are original pistons, they should have a CH of 1.56". But if they're aftermarket replacements, they're prollably going to be the shorter rebuilder type.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 02-03-2013, 07:11 PM
Registered User
 
Join Date: Apr 2011
Location: new hampshire
Posts: 31
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
The 60 is under the the rest of the number . What do you mean ch of 1.56
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 02-03-2013, 08:44 PM
BigEd36's Avatar
Registered User
 
Last photo:
Join Date: Nov 2009
Location: Auburn, IN
Age: 65
Posts: 386
Wiki Edits: 0

Thanks: 17
Thanked 43 Times in 39 Posts
Quote:
Originally Posted by firebird7980 View Post
The 60 is under the the rest of the number . What do you mean ch of 1.56
CH - Compression Height - is the distance from the center of the piston pin to the top of the piston. 1.56" is the compression height of a standard 350 piston. Many aftermarket pistons are what's called "rebuilder" pistons, they are only 1.54" compression height, or .020" shorter. The reasoning is that it's assumed when the engine is rebuilt the block will be decked, so making the piston shorter will keep the piston deck height (the distance the top of the piston is below the top deck of the block) will be the same. If your engine is rebuilt using "rebuilder" pistons and the block is not decked, now your pistons will be .020" further "in the hole" (down in the cylinder). That will lower your compression ratio, and add .020" to the squish/quench height (distance from the top of the piston to the cylinder head) which makes an engine more likely to have detonation problems or require higher octane gasoline to prevent the detonation.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 02-04-2013, 04:25 AM
Registered User
 
Join Date: Apr 2011
Location: new hampshire
Posts: 31
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Thank you
Reply With Quote Quick reply to this message

Recent Hotrodding Basics posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may 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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Piston ID number goodnigh Hotrodding Basics 3 07-03-2012 02:03 PM
Piston number question kohle1ce Engine 3 04-30-2006 01:34 PM
piston number 78 chevy truck Engine 27 06-24-2004 12:26 AM
piston part number confusion Sleeve396 Engine 0 04-13-2004 09:03 PM
piston number 78 chevy truck Engine 1 01-24-2004 09:44 AM


All times are GMT -6. The time now is 03:24 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.