Originally Posted by KNanthrup
So I've been trying to get my ignition timing figured out on my sbc 350 lately and im having a lot of trouble with it. The problem im having (as it seems) is that im not getting enough timing in the lower rpms (it sort of stumbles on hard throttle low rpm runs). So what I had done was I cranked the timing way up, which resulted in great low-mid rpm power but ended up dogging on the top end.
Just to get a solid start, I threw a piston stop on #1 today and hand cranked it both directions, made marks, and took the halfway point to verify TDC. It matched fine with my balancer mark.
So I pulled the vacuum advance off of the dist. and set total timing to 35* (a bit conserative), initial ended up at about 20* (still without vaccum advance hooked). I threw the vaccum on from direct manifold port (ive tried direct and ported with same result) and it brought timing up to around 30* (10hg vacuum pull at idle).
So with everything set as described, it just doesnt run right. It idles high with the direct vacuum (even with idle screw all the way out), mid range power is bad and it doesnt even feel right on the top end until its turning around 4500+rpms. The only way my motor feels right is when it's pulling a buttload of static timing.
So what gives?
I figure it may need the timing curve to be changed, but should it be fairly decent with a range of 20* initial to 35* total? Total timing comes in at about 2200rpms
More data, what engine (Ok somebody's 350), how big (figure it's 350), how old/miles on it, what cam, how much compression, type of piston, what carb, what distributor, what spark plug and wires, what intake, what kind of exhaust, what car/weight, what type of transmission, what are the rear gears? All this plays heavily with ignition tuning.