Originally Posted by RalphP

The Megasquirt is one choice, yes.

I'd rather keep it all original as much as possible *grins* Just a'hankerin' to tune something, and dasn't dare do SWMBO's Cougar until I have a proven record (it's why teh truck will be self-painted first; if I do good, I get to do her car. If I screw up, someone else does her car. I'm not sure which one is the better choice .... *grins* )

RwP

Originally Posted by robertmee

Well, the length of an arc is Deg * Radius * Pi / 180

So, 1 Deg and a flywheel radius of 3.88 inches, would give .06768 inches or a little more than 1/16 of an inch. A half inch would give you close to 8 degrees of advance.

Originally Posted by RalphP

I'm not sure the tone ring is only 7.75" in diameter.

Considering the same ring is used with the fly wheel for a clutch ... typically 11" or so in diameter.

RwP

Originally Posted by ragged89

I came up with a little less than 7.5 degrees for half an inch, using a quick calculation of the flywheel circumference and dividing that into 360. So either way a significant change is needed in the mounting position of the crank sensor to get a good start point on the "advance" side I'd say.