Go Back   The Supercar Registry > General Discussion > Pit Area - Racing


 
 
Thread Tools Display Modes
Prev Previous Post   Next Post Next
  #1  
Old 12-27-2002, 09:22 PM
Chevy454 Chevy454 is offline
Senior Member
 
Join Date: Mar 2000
Location: Alton, MO, USA
Posts: 11,923
Thanks: 0
Thanked 8 Times in 8 Posts
Default BBC compression mapping

This is a continuation of another post on this board, but I ran across some info that I felt prompted starting another thread. For those of you who are looking for a little more from you LS-6 or L-72 build up, read on...

In the earlier thread, Jim Lerum posted the compression mapping for a 454, which looked like this:

Intake valve closer/ Compression
IVC 68 degrees = 11.54cr
IVC 69 degrees = 11.64cr
IVC 70 degrees = 11.74cr
IVC 71 degrees = 11.86cr
IVC 72 degrees = 11.96cr
IVC 73 degrees = 12.06cr

As Jim says, "this formula involves % cylinder volume vs crankshaft angles". Well, at the time, he didn't have the numbers for a 3.76" stroke, but I have since ran across them. Here is what I found:

Intake valve closer/ Compression
IVC 68 degrees = 11.60cr
IVC 69 degrees = 11.71cr
IVC 70 degrees = 11.81cr
IVC 71 degrees = 11.91cr
IVC 72 degrees = 12.03cr
IVC 73 degrees = 12.14cr

What these numbers should be telling us is what the target compression ratio should be given a certain IVC (intake valve closing). Well, Jim guessed the IVC of the #3863143 cam to be 70 degrees, and I used the same range of numbers to map the 427. BUT, one problem I'm running into is finding the correct "seat to seat" timing of the cam. I've found them measured at .006", .015", and .050", but they don't seem to match up with what I need. So, anyone have a 3863143, a degree wheel and a cam doctor? [img]/ubbthreads/images/icons/grin.gif[/img]
Reply With Quote
Click here to view all the pictures posted in this thread...
 

Thread Tools
Display Modes

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

Forum Jump


All times are GMT. The time now is 10:53 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2025, vBulletin Solutions Inc.

O Garage vBulletin Plugins by Drive Thru Online, Inc.