Eddie wrote:Pat,, I know you are VERY knowledgeable but I gotta ask. Did you check to make sure there is minimal 'slack' in the timing events by moving the crankshaft and checking the damper in degrees,(X2), in regards to actual rotor movement? With the timing chain, Intermediate gear drive to cam gear, and finally the rotor phasing? This is where I would start. If there is too much machining tolerance 'Stack up" then there is not much that can be done without replacing parts for new ones. Don and dave hughes are exceptionally Malcontents!
Adrian Worman wrote:I agree with that entirely Fabien
Vac advance on a street car for me is essential. You can't possibly dial in enough initial to match the 50 or so degrees of advance a vac can will give on the overrun or light throttle.
I still don't entirely understand the use of a non vac dist in anything but a dedicated race car
Adrian Worman wrote:So it's the slowness to respond then that makes vac not so popular on more extreme street engines
I used an FBO limiter plate on my 440 and set the initial at 20 deg, installed the plate at the 14 deg slot, total mech adv 34 deg and 18 deg of vac, 52 in total. Runs like a dream on the road and broke into late 12's last time out with everything hooked up on street tyres, 3.23 gears and appalling smoking 60 ft times of 2.3 seconds.
I know there's a half second to come of that on headers and sticky tyres.
Eddie wrote:,,but the spark advance is strictly PCM controlled and very accurate.