Questions about using a timing light

[68 P.O.S.]

Originally Posted by rsgt

I have read a lot about this on the team Chevelle forum and this seams to be the most popular way to set up the 350. I have done this to my 72 truck and it has never run this good. You have to make or you can buy a vacuum advance limiter. Attached is a picture of the one I made from a piece of aluminum. Crane sells one. You want to limit the vacuum advance to 8 to 10 degrees. Set your initial to 10 or 12. This gives you 20 or 22 at idle. A lot of the forums talk about this.

You are correct, this has been a thing here in the past too, as well as many other forums, and it has worked with great success. It seems the topic has dropped off here and people have forgotten about it. It’s really simple and works wonders: Buy the Crane 99600-1 adjustable vacuum canister kit, replace the current springs in the dizzy with 1 blue and 1 silver spring (if I remember the colors correctly) so the mechanical is fully advanced by 2500-3000 rpm, limit the vac can to 10 degrees by placing the stop on the opposite side of what the instructions say, adjust the vac can 4 turns out from bottomed out (should pull at approx. 7 in of vac), advance total timing to 34-36 degrees with vac can disconnected and plugged, check timing at idle to see where your initial timing number falls for fyi purposes, plug the vac advance back in to manifold vaccum, NOT ported, and adjust idle to 600rpm in gear with your foot on the brake (usually works out to 750-800 rpm in park), and then you should be in there like swimwear.