To Vacuum Advance or Not to Vacuum Advance
Adding more timing at part throttle will reduce exhaust temp by a bunch and you'll improve fuel economy. You said you didn't care about gas mileage but I bet you care about excess fuel washing down your cylinder walls. You might also care about a 300 or 400 degree difference in exhaust gas temp.
Well; the headers will last longer if not approaching cherry red some/most of the time. Not to mention the underhood temps.And anything near the headers.......oh like, say the wires and such.
To the streeter that says the Vcan is not needed, any guy, no one in particular ;
The expanding exhaust gases need to transfer their energy to the crank to make locomotion possible, and there is a theoretical best time to do this, to maximize power output. If the pressure peak comes too late, the engine will not make it's optimum power. If the peak comes to early, the pressure gets stalled by the crank being semi-immoveable. When you start the fire,,in large part, determines when the pressure peak happens.
The mechanical advance system, from stall speed on, determines this peak pressure transfer point..... at WOT.
But honestly, how much time does your street engine spend at WOT, compared to Part-Throttle? Would you guess 3 or 4 seconds per hour? Or maybe you are a wild man, and spend 15 seconds per hour at WOT and 59:45 at some other throttle setting. Ok wait, you say you are really wild and spend 2 minutes per hour at WOT; which being around 30 x 4 second WOT runs to the speed limit in that hour, or once every 2 minutes.. That's really really wild.
Ok 2 minutes per hour maths out to 96.7% of the time is spent at not-WOT. So 96.7% of the time spent above idle, without a Vcan, your engine is operating with the wrong timing. No wonder the fuel-consumption is thru the roof. No wonder your oil needs changing every week. No wonder your rings wear out early. No wonder...... a lotta things.
There are times, at part throttle, when the street-engine is wanting timing perhaps in the 50* plus range,maybe pushing 60* and if you have only 20*, or even approaching 30* at that time, then the fire may not even be finished burning inside the chamber, and so finishes in the header............ which destroys the overlap cycle, and destroys the headers ability to do it's job, and of course makes a lovely red glow.
But ,you say, you don't need a Vcan. Hey; it's your money, you can burn it if you want to. Me; I can't afford that.
Of course if your car is a racecar, and you trailer it to the track, this does obviously not apply, cuz your engine operates mostly in two modes; idle and WOT,lol. Still, I can see times the engine could benefit from a Vcan, just used in a different way.
End rant.
