Anyone know the stock compression ratio for a 1979 350 chevy ? - 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 06-05-2012, 10:35 AM
Registered User
 
Last photo:
Join Date: May 2012
Location: Bayonne NJ
Age: 22
Posts: 167
Wiki Edits: 0

Thanks: 7
Thanked 2 Times in 2 Posts
Anyone know the stock compression ratio for a 1979 350 chevy ?

it came out of a truck and as far as i've researched it had 175 hp and 250tq back in the day, previous owner said it is completely stock, does anyone know the compression ratio that came in this engine ? or perhaps the cc's of the pistons

I'm trying to get an accurate compression estimate because i just bought a set of 305 cylinder heads 601 casting which have been ported and machined to have 58cc chambers and 2.02 intake and 1.60 exhaust valves

the engine has a slightly more aggressive than stock cam and i'm hoping for a tad bit under 9:5:1 compression so i can run 89 octane

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 06-05-2012, 10:40 AM
Madmax305's Avatar
Registered User
 
Last photo:
Join Date: Jan 2010
Location: Brea, Ca.
Posts: 249
Wiki Edits: 0

Thanks: 1
Thanked 2 Times in 2 Posts
I don't know exactly, but you can figure in the 8.5-9.0 compression ratio.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 06-05-2012, 05:23 PM
Registered User
 
Join Date: Aug 2006
Location: Alexandria, VA
Posts: 1,762
Wiki Edits: 0

Thanks: 4
Thanked 66 Times in 64 Posts
If its stock, then not more than 8.5.

If you measure it you may find some engines calculate out as low as 8.1.

Bruce
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 06-05-2012, 06:09 PM
GMCBEAST's Avatar
Registered User
 
Join Date: Apr 2011
Location: Kingsport, TN
Age: 34
Posts: 64
Wiki Edits: 0

Thanks: 1
Thanked 0 Times in 0 Posts
I agree with above, 8-8.5:1. Those 76cc heads (Most likely what you have) kill compression, throw in a dished piston and you end up on the low end of the C.R. ladder. On the good side you don't need premium gas. If they are dished pistons I think they are 18cc cups, I'm not positive though, 58cc chambers are ok with dished or most 4 valve relief flat tops but you need to pay close attention to your timing with the flat tops. Summit and Wallace Racing have a compression ratio calculator on their site's once you figure out your specs. Hope this helps.

Last edited by GMCBEAST; 06-05-2012 at 06:20 PM.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 06-11-2012, 02:29 PM
78novaman's Avatar
The AMC, FORD, & CHEVY Guy??!!
 
Last wiki edit: Improving fuel economy
Last journal entry: Finally on the road
Last photo:
Join Date: Nov 2002
Location: Central Ohio
Age: 31
Posts: 299
Wiki Edits: 0

Thanks: 0
Thanked 3 Times in 2 Posts
According to my Hayne's manual:

8.2:1 for light duty trucks
8.3:1 for heavy duty trucks

All I can think is maybe slightly different pistons???
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 06-11-2012, 09:31 PM
Registered User
 
Last photo:
Join Date: Mar 2012
Posts: 94
Wiki Edits: 0

Thanks: 2
Thanked 2 Times in 2 Posts
My Firebird with a 305 is at 8.5 right now stock, yours should be in the same relm
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:
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
compression ratio on 350 chevy dar100e Hotrodding Basics 3 03-23-2011 12:44 PM
compression ratio of a stock 96-00 vortec engine?? redfish211 Engine 24 02-22-2011 07:56 PM
Pontiac 350 compression ratio? AndersonRacing44 Engine 3 07-21-2010 08:51 AM
stock compression on sbc chevy 302 327 or 350 dustinweaver Engine 5 04-07-2006 10:11 PM
compression ratio for a 350 sbc??? classic_chevy_guy Engine 6 10-27-2003 11:44 AM


All times are GMT -6. The time now is 02:35 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.