Hot Rod Forum : Hotrodders Bulletin Board - View Single Post - Cam Selection help
View Single Post
  #2 (permalink)  
Old 03-20-2008, 11:30 PM
techinspector1's Avatar
techinspector1 techinspector1 is online now
Senior Curmudgeon
 
Last wiki edit: DynoSim combinations Last photo:
Join Date: Oct 2005
Location: Hemet, California, USA
Age: 72
Posts: 12,946
Wiki Edits: 326

Thanks: 760
Thanked 1,012 Times in 848 Posts
You didn't give two of the important details. Piston deck height and compressed head gasket thickness. These determine the squish. Guesstimating the gasket at 8 cc's (0.040") and the piston deck height volume at 5 cc's (0.025"), your static c.r. will be 10.56 and the cams you're looking at would work. Problem is, adding the gasket and deck gives a squish of 0.065". This may be too thick to allow operation on pump gas without detonation (ideal 0.035" to 0.045").

If whomever built the motor took squish into consideration and set it with, for instance, 0.025" deck and used a 0.015" steel shim gasket, then the squish would be at 0.040" but the static c.r. would be 11.23:1, so it wouldn't run on pump gas anyway, even with a tight squish (IN MY OPINION).

Now, you could go with a longer cam and try to squeak by with leaking off some of the compression, but you're already limiting yourself because the heads are gonna sign off about 5,000 rpm's and the cam you're lookin' at will operate from 2200 to 5700. If you went longer on the cam, you might operate from, for instance 2800 to 6200. Then the heads would be a mis-match and the converter would be a mis-match.

Who chose the parts for this motor anyway? What's the piston deck height? What's the gasket thickness?

Last edited by techinspector1; 03-21-2008 at 02:30 AM.
Reply With Quote