We just finished a freshen up and I'm interested in testing cam timing or more specifically where the cam is degreed compared to the crank. I tested 4 degrees advanced vs. straight up in a street/strip car several years ago and the difference in ET was astounding. It made a .1 difference in the 1/8 and the throttle response changed significantly. This combination loved advanced cam timing!
I'm sure a race combination with high stall, larger cam and high compression may react much differently.
Have you tested cam timing on the track or dyno? What was your result?
Matt Ward
Posts: 1389 | Location: South Carolina | Registered: March 20, 2004
I saw a guy "TEST" cam timing at the track one day , advanced his cam somewhere around 5-6 * , end result was 8 bent valves .. be careful ....
I always degree mine, and put it where I want it installed, make notes , then move it to 2 , 4 , and 6 degrees each way and write down the clearances , so I know whats gonna happen "if" I decide to track test it ...
Posts: 784 | Location: hopefully pickin up a check in the winners circle | Registered: November 29, 2006
Originally posted by Brktracer: We just finished a freshen up and I'm interested in testing cam timing or more specifically where the cam is degreed compared to the crank. I tested 4 degrees advanced vs. straight up in a street/strip car several years ago and the difference in ET was astounding. It made a .1 difference in the 1/8 and the throttle response changed significantly. This combination loved advanced cam timing!
I'm sure a race combination with high stall, larger cam and high compression may react much differently.
Have you tested cam timing on the track or dyno? What was your result?
I have tested at the track a couple times. Didn't see a whole lot either way. I agree converter stall plays a larger roll. Higher the stall is in relation to shift point I think the less it matters. Also the higher the stall is in relation to where the engine makes peak torque seems to lesson the effect. Now if stall is lower than peak torque it makes a more profound difference.
Originally posted by Paul S/Q: I saw a guy "TEST" cam timing at the track one day , advanced his cam somewhere around 5-6 * , end result was 8 bent valves .. be careful ....
I always degree mine, and put it where I want it installed, make notes , then move it to 2 , 4 , and 6 degrees each way and write down the clearances , so I know whats gonna happen "if" I decide to track test it ...
Great advice! I currently have over .150" clearance on the exhaust and over .180" on the intake when installed straight up. I wouldn't dare run it without checking clearance first. In other words, this wouldn't be an at-the-track change. (Test springs make checking the clearance really easy.)
I'd like to hear some results though. Maybe it's not worth my time.
Matt Ward
Posts: 1389 | Location: South Carolina | Registered: March 20, 2004
Originally posted by Brktracer: [QUOTE] Great advice! I currently have over .150" clearance on the exhaust and over .180" on the intake when installed straight up.
wow .... why so much ? you are giving up a lot of cam and or compression .... were these off the shelf pistons ? ...
Posts: 784 | Location: hopefully pickin up a check in the winners circle | Registered: November 29, 2006
I used a different engine builder to rebuild my engine and instead of degreeing the cam at 102* CL that I requested, he decided it really needed to be at 104* . Lost 0.20 et and 2 mph in the 1/4. Putting more fuel in it by going down 4 pill sizes got 0.10 and 1 mph back.
Posts: 2459 | Location: 53056 | Registered: December 30, 2009
3500lb street/strip car w/406 SBC. The cam degreed significantly larger than I expected so I installed it with 8 deg adv (104). Later on, I decided to try it at 4 deg adv (108). With a relatively tight converter (3500 flash), it made almost no difference. Short time got a bit worse, but it made it up in the rest of the quarter.
Posts: 722 | Location: Somers, ny | Registered: October 15, 2001
I've set the cam timing without the valve train installed then checked it with everything in place and with both a double roller and a Jesel belt drive the setting retarded right at 3 degrees. Now I just allow for the 3 degrees.
TAKE IT TO THE BANK!!!!! Later, Bill Koski
Posts: 11005 | Location: LAS VEGAS. NEVADA, US of A | Registered: December 03, 1999
