crank pulley timing marks

[anthony7777]

gents, a while back i read some place about dividing and marking the healey crank pulley into degrees, i.e. "btdc"/"atdc" my aged memory will not allow me to recall, was it here? yes i did do a "search" but could not pull up the info.thanks. /ubbthreads/images/graemlins/rolleyes.gif

 

[dklawson]

It may have been here. It's not a hard thing to do for any car.

Carefully measure the OD of the crank pulley (make several measurements and average them). Take the OD and multiply by PI (3.14159). That will give you the circumference around the pulley.

Now determine which marks you want (10 BTDC, 20, 30, etc.) Create a ratio for each degree mark you want (i.e. 10 degrees/360 degrees = 0.0278) and multiply that by the circumference. That will tell you where to make the marks (linearly) along the circumference of the pulley.

Say you have a 4" OD pulley and you want a mark at 10 degrees. The circumference for a 4" pulley = 4 x pi = 12.566" A timing mark at 10 degrees would be 12.566" x 0.0278 = 0.349" from the Zero degree timing mark. You can cut a strip of paper 12.566" long, make a mark 0.349" from one end of the strip, wrap the strip around the pulley (aligning the cut end with the Zero degree mark on the pulley), and center punch the mark at 0.349" to make a dimple at 10 degrees on the OD of the pulley. Fill the dimple with white paint and you're good to go.

 

[anthony7777]

dklawson,yes the calculation are correct,my guestion stemmed from a friendly argument with a buddy of mine who told me a generic "crane timing wheel disk" could be used on any engine, ya a single timing disk template that can be used on all engines, it would have to have so many markings you couldnt read it or it would have to be blank so you could fill in your own info.just trying to get him to understand that "timing is everthing" thanks for responce. /ubbthreads/images/graemlins/rolleyes.gif