Distributor Phasing Question

KitCarlson,

You sound like a hard-core designer. The problem for me is ideas are many and life is short. I am lucky to occasionally be allowed to develop new designs at my day job, but aerospace instead of auto.

I agree that using just the distributor for spark timing, but in a distributorless system is the best balance for retrofitting old engines. I expect someone will come out with a turn-key system soon. Retrofitting a crank sensor is not trivial, given the varying components and pulleys on even the same engine type (ex. SB Mopar). Adding a cam sensor to avoid "wasted spark mode" makes it even harder. If the spark controller ultimately increases spark until knock is sensed, wear in the timing chain hardly matters, so why not just use the distributor directly?

Re resolution, even 36-1 crank wheel systems use a digital timer to interpolate between teeth, so doing similar in the distributor is reasonable. I don't know how many teeth in the new Hemi's "toner ring", but doubt >36. Still, I don't see how one can avoid customizing the distributor pickup since distributorless requires a TDC marker, so why not add more teeth for better resolution at the same time?

Back to my original post, everyone above concurs that the rotor won't move too much to not align with the post, even without advance weights. It works in both production engines (GM "computer" distributor) and many after-market racing distributors. Interestingly, I ran across a slant six distributor cap on e-bay described as special, with "wide contacts", which might work better. I also found posts on www.slantsix.org about new rotors with a short tip that causes mis-fires, even without a rotor phasing problem. Distributorless takes care of all those concerns.

For now, I will keep the weights and vacuum advance and let the computer add tweaks to that. That makes it easy to swap back to no computer control if stranded on the road.