anyone know why wrist pin offset is important? - 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> Electrical
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 11-25-2003, 08:34 AM
57Waygone's Avatar
New Member
 
Join Date: Mar 2003
Location: Austin
Posts: 17
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
anyone know why wrist pin offset is important?

Thanks for any information you can supply.

Ron
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 11-25-2003, 09:28 AM
troy-curt's Avatar
Shop Owner And Troll Hunter
 

Last journal entry: Detailing Eng. Compartment
Last photo:
Join Date: Apr 2003
Location: Prairie Grove Ar.
Age: 75
Posts: 2,646
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Supposed to keep the pistons from rattling by pushing them to the side of the cylinder.

Troy
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 11-27-2003, 10:09 AM
Sandflea427SS's Avatar
Anything with a throttle
 
Last photo:
Join Date: Apr 2003
Location: South Central Pa
Posts: 440
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Turning the pistons around is an old moon shiner trick according to Smokey Yunick. Smokey went as far as producing "math" that
calculated the maximum distance to offset the wrist pin to produce the maximum amount of HP gain. In the article, he mentions that with "modern" technology, the car companies didn't offset the wristpin anymore. He said in the old days, you could just install the piston "backwards" and get more HP. He felt that piston makers should offer offset pistons for race car. He did say said if you bought enough you should be able to get your
piston maker to do this. He indicated that every winston cup team did this.

Smokey said you might get a little bit more wear on the piston skirt and a little bit more noise. I can't tell any difference on engines that have this treatment. You certainly can't with a header. The piston will "travel" a small amount extra so you have to be carefull about valve openings and deck heights.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 11-27-2003, 10:55 AM
BOBCRMAN@aol.com's Avatar
Member
 
Last photo:
Join Date: May 2002
Location: Holly, michigan
Posts: 7,954
Wiki Edits: 0

Thanks: 13
Thanked 218 Times in 207 Posts
In a hotrod motor pin offset is not usually an issue. The OEM builders do this for cold piston noise controll on cast pistons. I have built long rod 400's and 383 street motors where installing a street cast piston backwards helped with internal clearances. Smokey and a few other old time engine builders say it also improves rod angle and torque output. Forged racing pistons usually have a centered pin as they are noisy anyway.
One of GM's biggest warranty problems now is the short skirt, minimal offset pistons they are running in the new cars. I change many sets of these each week. They are replacing them with a tighter fit piston and coated skirts. New car customers don't like that rattle in the otherwise silent (except for belt noise) powerplant when first started cold.
Reply With Quote Quick reply to this message

Recent Electrical 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



All times are GMT -6. The time now is 05:30 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.