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-   -   cam timing (https://www.racingjunk.com/forums/showthread.php?t=30711)

john910 07-18-2011 04:14 PM

cam timing
 
over the winter i replaced my cam.. the car is i900lbs . power glide w/brake. 350 sbc 30 over . last year the cam was comp cams 292 , 501 lift hyd. cam 202 valves, vortec heads. 750 holley. car ran 6.50 -60s 1/8 mile. with 60-fts at 1.44. then i had a cower cam #00357 587 lift mech. installed with a adjustable cam gear, and have it set @ 0. with 35 degees timing. car runs the same as last year. my question is what wound help in timing advancing the gear 2 or 4 or more degees

zipper06 07-18-2011 09:26 PM

I would suggest advancing the cam 4* and timing 40* BUT i think the cam is still too small for that weight car, it would run better with a 6.30/6.40 lift cam.

JMO

Zip.

john910 07-22-2011 04:54 PM

cam timing
 
now if i advance it, will i have any issues with valve to piston clearance. or will that stay the same. thanks for your help.

wazup 07-22-2011 07:43 PM

I agree with Zip on the bigger cam, something in the low six hunderds or advance the cam in the engine. This will give a little more bottom end power and when you advance it you will bring the intake valve closer to the piston. Would really need to know what size pistons and where the valves open and close. I would advance the cam and check the PVC this should help.

oldandtired 07-23-2011 07:08 AM

Re: cam timing
 

Originally Posted by john910
now if i advance it, will i have any issues with valve to piston clearance. or will that stay the same. thanks for your help.

For stock motors, .045 is the minimum valve to piston clearance
On High RPM motors, use .080 on the intake and .100 in the exhaust.

1. Write down the lash you will use (example Int = .028, Exh = .030.
2. With the cam on the heel, adjust the lash to zero, do not lock the polynut.
3. Put a dial indicator on the rocker, just above the spring retainer.
4. Intake number = .080 minus lash (example .080-.028 = .052).
5. Tighten the poly nut .052.
6. By hand, rotate the crankshaft while watching the rocker go up and over the nose of the lobe "feeling" for interference.
7. If none, tighten another .020 and rotate again. Repeat and you will eventually find your clearance.
8. Repeat for the exhause (example .100 - .030 = .070).

If you change the advance on the cam, you must start over.
JMP but works from me.


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