Dragula

I have a new MSD distributor and 6AL setup that I will be putting in my car shortly. The advance can be adjusted by switching springs and bushings. The instructions have charts for when the curve comes in. I know I need to have about 36 degrees total advance with the vacuum canister unplugged (give or take based upon detonation). I have also heard to make sure that all 36 degrees are in somewhere around 3000 RPM. What do you guys think? Is this too quick or should I slow down the advance and have it coming in at a higher RPM.

Dragula

Nobody knows the answer to this?

GregWestphal

iTrader: (1)

I'll take a shot at this. How fast you bring in the timing depends on how much compression your engine will have (static and dynamic compression, check how much cranking compression you have), how tolerant the heads are to low/mid-rpm spark advance, what octane of gas you'll be running, and the powerband of your engine.

For my 355, I have a little over 11:1 static compression and 225 psi on the compression test due to the relatively-small LT4 HOT cam (compared to the CR). I ramp up the timing to 26 degrees at 3600 rpm, then gradually increase it to 28 degrees by 4800 rpm (burn my own chips). I can run another degree of timing, but any more and it detonates. Also, my powerband is from ~4000 rpm to 6200 rpm, so when I manually shift the auto tranny, I never drop below 4000 rpm.

So, I'd bring it all in by 3600-4000 rpm depending on the low end of your powerband. A plus to this is that less timing at the lower revs will help kill some of the low-end and mid-range torque at WOT, which will help you hook up at the track.

Dragula

Cool...I'll be running 10:1 with aluminum heads. CompCams 236/236 @ .050" solid roller with .550" lift on both lobes. I'll set it first like you said and play from there. I was kinda worried about the low end torque (~515 lbft )