My timing is set at 16* initial, mechanical is 18* at 3400 and the vac can is 14* at 14 inches. I have it connected to manifold vacuum so it had 21* total at idle.
I have been looking at the stock 340 cam for my car, I'd be fine with that.
I missed something here; Earlier you said the idle vacuum was 15inches at 850rpm.
Well if the Vcan is able to pull in 14* at 14inches, AND the initial is 16*, then, with the Vcan hooked to manifold vacuum,shouldn't the engine be idling on 16*initial plus 14*Vcan at 850 =30 degrees?
What did I miss?
the reason I ask for clarification is cuz;
If the Vcan is non-linear (and they mostly are), and the vacuum drops to say 10 when you put it into gear, then perhaps the can would lose it all, and the timing would revert to the 16 initial. And it would do it almost instantly. Dropping from 30* to 16* would sure kill the idle.
34* at 3400 works for me with aluminum heads and 10.9Scr, and 8.6Dcr. If you have a linear advance curve you are running about .75degrees of mechanical advance per 100 rpm . At a cruising speed of 2600rpm, that might translate to 42degrees of cruise timing. This is probably 10 degrees short of optimum. But with your combo that is sometimes the way things are. So if you spend a lot of time on the hiway, there are some tricks available.