350to a 383 compression difference - 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> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 08-14-2010, 09:23 PM
Registered User
 
Join Date: Jun 2007
Location: pickering
Posts: 243
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
350to a 383 compression difference

If i swap all my parts from my rotating 350 assembly and put in a 383 rotating assembly with my same 041 heads.Will i change the compression drastically, again using the same cc volume pistons ,head gasket etc but for a 383,and instead of a XE268, put in a XS274s,or even a XS282S, current compression 10:1 in the 350.

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 08-14-2010, 09:51 PM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,024
Wiki Edits: 0

Thanks: 3
Thanked 358 Times in 354 Posts
When using 64cc heads on a
383 use a dished piston to keep it pump gas friendly.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 08-15-2010, 12:40 AM
ericnova72's Avatar
More for Less Racer
 
Join Date: Jan 2007
Location: S.W. Lower Michigan
Age: 47
Posts: 9,222
Wiki Edits: 0

Thanks: 26
Thanked 422 Times in 386 Posts
With all variables kept the same, just changing from 3.48" stroke to the 3.75" stroke will result in the 383 having .5-.6 more compression due to the larger swept volume(more cubic inches) being squeezed into the same size space at TDC. Your 10-1 will become 10.6-1.

Compression ratio calculator here at www.wallaceracing.com on the calculators page
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 08-15-2010, 06:04 AM
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
Quote:
Originally Posted by sapsz28
If i swap all my parts from my rotating 350 assembly and put in a 383 rotating assembly with my same 041 heads.Will i change the compression drastically, again using the same cc volume pistons ,head gasket etc but for a 383,and instead of a XE268, put in a XS274s,or even a XS282S, current compression 10:1 in the 350.
Besides the rise in CR, the pistons for a 3.48" stroke crank will have the wrong compression height.

So, since you have to change pistons or rods anyway, the best choice is to use a "D"-shaped cup piston w/the correct volume to keep the CR where you want it.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 08-26-2010, 12:40 AM
Registered User
 
Join Date: Jun 2007
Location: pickering
Posts: 243
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
350to a383

I was thinking a 3.75 scat 9000 crank, scat 6 inch pro comp rods floating pins, 7/16 cap screws, clearanced for strokers, but I have no clue as to the type of piston i neeed,the cam will be a Comp solid flat tappet grind # 12-677-4,or12-676-4.
Asfar as the pistons any recommendatrions the block is .060 397010 with 041 heads fully ported 2.02-1.60 254cfm@.600 lift flow bench tested,before last rebuild,due I go forged ,hypereutectic,?, I will not be adding any power adders,but I do intend on using the cams full potential any suggestions D shape ,2 valve releifs ,4valve releifs I'm not very good in this dept. I dont want the compression higher than 10.50-1 --11.00-1 we have 94 octane here plus the availabability of additives makes getting 100 octane no problem to put in the tank. Any help would give me peace of mind fellas.Thanks everyone
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 08-26-2010, 01:51 AM
ericnova72's Avatar
More for Less Racer
 
Join Date: Jan 2007
Location: S.W. Lower Michigan
Age: 47
Posts: 9,222
Wiki Edits: 0

Thanks: 26
Thanked 422 Times in 386 Posts
A zero decked block and a 2 valve relief piston(4cc) will get you 11.1-1 if you truly have a 64cc head.

Your 041's probably were bigger than 64cc when new, likely 66cc, and it is hard to say how big they are now if the port work was done right, relieving the chamber around the intake valve would make them bigger yet, then some milling might have taken some volume back off. You really have no idea what they are now.

Best thing you can do is get a 30-50cc syringe from the pharmacy or a veterenarian and along with an old CD check the chamber volume so you know what you are working with.

Block the head up level on the bench seal the valves lightly with a little grease, install a spark plug, and seal the CD to the deck surface with some grease(or Vaseline) to make a pocket that will hold liquid. Add some food coloring to some water or rubbing alcohol and fill the chamber thru the CD center hole and record the volume needed to do it.

Then you will be able to make accurate decisions, anything less will just be a big guess.

I consider forged pistons the only choice, especially with the rpm capability of the solid cam. Keith Black/ICON forged or Probe are good low cost forgings.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 08-26-2010, 05:13 AM
Registered User
 
Join Date: Jun 2007
Location: pickering
Posts: 243
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
350to383

Thanks alot you sure are an eye opener.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 08-26-2010, 09:58 AM
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
Do be sure to use a CD or piece of plexiglass, plastic, etc. w/a hole in it for adding water and allowing air to escape.

If you don't use a cover like that, the surface tension will allow you to add a LOT more water than the chamber's actual size. You wouldn't think it would be all that much, but it is.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 08-26-2010, 09:38 PM
Registered User
 
Join Date: Jun 2007
Location: pickering
Posts: 243
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
350 to 383

Thanks a bunch Cobalt.
Reply With Quote Quick reply to this message

Recent Engine 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
sb350 no compression underthegallows Engine 19 04-13-2010 12:35 PM
350 vs 383 build for performance Biscuit6447 Hotrodding Basics 20 03-05-2010 08:42 AM
350 to 383 "Camparison" ssmonty Engine 5 05-17-2007 07:17 PM
Most compression for Pump gas? NWayne Engine 19 03-09-2007 01:46 AM
Best blocks for 383 chevy, there is a difference roys63 Engine 20 03-20-2003 08:38 AM


All times are GMT -6. The time now is 10:10 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.