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You got more economy and perf. by taking timing out? I thought the idea behind good quench was to be able to run more timing/comp. w/o fear of detonation/ping? I run 16-18 initial and 36-38 total now but maybe I'll play with it and see. Have to wait till spring, car is sleeping in the garage now and we're in the middle of a 12" dumping right now!



You only want as much timing as necessary to wind up with max cylinder pressure at approx 20-30 degrees ATDC. With a good quench and port velocity the mixture is mixed much better due to the turbulence in the chamber and requires less total timing to get max pressure at 20-30 ATDC.

So with better heads with improved port design and a good quench it will require less total timing to make max power. Small Block magnum heads make best power with 32-34 degrees of total timing where as the open chamber LA heads require 34-36. The new GM LS series heads are running less than 30 degrees of total timing for best power.

On the other end you need more initial timing as the duration of a cam goes up due to the inefficient filling of the chamber due to the over lap. That's while to get a decent idle on a big cam you wind up running high teens or more of intial. Same thing that extra time is required to create max cylinder pressure at the 20-30 degrees ATDC.

Dave Clement Pembroke, MA 03 PT Cruiser GT Turbo 99 Dakota SLT+ CC 4x4 68 Barracuda sport coupe http://home.comcast.net/~dgc333/