I never knew what my timing was set at because I never had a timing light. I'm new to the timing world. I know I must learn how to tune my timing curve for those extra ponies. I usually just use a vacuum gauge, which I don't think is enough. I got a timing light today and I don't think that my timing marker on the timing chain cover is right.

71 Chevelle
350 @ .040 over 9.5:1
Accel HEI
Comp xtreme 256 212/218 @ .05 / 110* Lobe
NGK plugs
Fluid damper

By the vaccum gauge my timing is turned back or I thought so. When I put the light on it it reads about 19* initial and maxes out at under 30* with the vacuum advance unhooked. How can I tell if this marker is right? Can I have some timing basics?

How do I change the timing curve?

Thanks

To check if the timing mark is correct:

1. Bring #1 piston up to TDC using a piston stop or by looking at the lifters (both valves on #1 piston should be closed at TDC)

2. Put a mark on the harmonic balancer where your marker shows 0,

3. Turn the engine (by hand) Counter Clockwise until you reach TDC for #1 piston. Mark this spot on the balancer.

4. True TDC is half way between the two marks you made on the balancer. Mark the balancer again with a different color to show TDC (white works well).

5. Check to see if your mark is at 0 on the timing marker when the piston is at TDC. if it isn't, but an adjustable timing marker and adjust it so 0 is even with your true TDC mark on the balancer.

Chevy engines tend to like 36-38 total timing (vac advance NOT hooked up). I don't know how to acheive this so maybe one of the veterans here can show us the way.