Thread: Degreeing cam
View Single Post
  #1 (permalink)  
Old 05-16-2014, 06:55 PM
Texasdoc's Avatar
Texasdoc Texasdoc is offline
CC Member
Visit my Photo Gallery

 
Join Date: Feb 2012
Location: Keller, TX
Cobra Make, Engine: Lonestar Classics LS427. Self-built 408W, AFR 195 heads, Performer RPM Intake, Quick Fuel 750, 407rwhp, 479rwtq
Posts: 549
Not Ranked     
Default Degreeing cam

OK, what am I doing wrong? Brent, feel free to chime in here.

Trying to degree my new custom Comp cam. These are the steps I've taken.

1. Install a pointer and verify crank and piston 1 is at TDC. I have a dial caliper. I have verified TDC by visualizing the #1 piston is at the top of the stroke (head off), and then using a dial caliper to measure .050 travel before TDC and .050 travel back down after TDC. Both readings are the same on the cam dial before and after the TDC mark. So I know the motor is at TDC and the cam indicator dial is accurate.

2. Insert a sold lifter into intake #1's bore. I know this isn't a roller lifter, but it should still work. Set the dial indicator onto the top of the solid lifter. Rotate the crank until the lifter rises .050. This is 20 deg BTDC. Keep rotating the crank until the lifter reaches full lift, then goes back down. Stop when the dial gauge reads .050 before it gets back to zero. This reads 250 ATDC.

3. Add 20 + 250 = 270. Divide by 2 = 135. This should be the installed centerline, right? My cam card says: Valve timing at .050 should be intake open at 9 BTDC, close at 41 ABDC (221 ATDC). Cam installed 106 degree intake centerline.

OK, so what am I doing wrong? The cam is installed straight up. Why would I be off by 11 degrees on the opening, 29 degrees on the closing, and 29 degrees off on the intake centerline?

Any suggestions?
Reply With Quote