rwatson5651

iTrader: (5)

Can anyone explain why the 12a requires 20 deg. difference in leading and trailing and the 13b is 10 deg.?

Jeff20B

iTrader: (13)

Why? Emissions, combustion chamber shape (compression dish), spark plug location etc.

You can do a 10 degree split. I tend to do that on my stuff. Or try 15 degrees. Whatever works best for you.

j9fd3s

iTrader: (3)

Jeff is correct, as emissions standards change, timing does as well.

i tested an FC, and with timing +10, nox was higher, but HC and co were the same. the cat may mask a change in HC or CO. a healthy rotary with a cat will have HC's in the 20's, and without the cat it will be around 1900.... removing the airpump adds another 1000

anyways, at idle you want timing to be -5 BTDC L or at TDC, up to you, what ever the engine likes. at WOT you're also looking for what the engine wants, somewhere between 18BTDC L and about 26BTDC L.

once you're in the sweet spot (^^^) more timing isn't going to make much more power

rwatson5651

iTrader: (5)

Thanks!