The Ford Barn - View Single Post - Finally some Cam Degree Numbers

Brian · 10-22-2020, 05:57 PM

I think Jack is right, ie, they measure from base circle...
however, going by your numbers you have;
ex opens 59.58 BBDC
ex closes 9* ATDC
This gives a duration of 248.5* as opposed to their stated 260*
Looks like your opening is close, however the closing is too early.
The closing events are more important than the opening....so, if you retard the cam by the one tooth as I suggested earlier, the new figures will be;
open 51.5* BBDC
closes 17* ATDC
duration obviously remains the same @ 248.5*
Furthermore, by doing this the distributor timing will be knocked back 16* and will be near where it should be.
My opinion....
I would have checked both inlet and exhaust timing events during the initial assembly

10-22-2020, 05:57 PM	#5
Brian Senior Member Join Date: May 2010 Location: Masterton, New Zealand Posts: 3,834	Re: Finally some Cam Degree Numbers - Now what? I think Jack is right, ie, they measure from base circle... however, going by your numbers you have; ex opens 59.58 BBDC ex closes 9* ATDC This gives a duration of 248.5* as opposed to their stated 260* Looks like your opening is close, however the closing is too early. The closing events are more important than the opening....so, if you retard the cam by the one tooth as I suggested earlier, the new figures will be; open 51.5* BBDC closes 17* ATDC duration obviously remains the same @ 248.5* Furthermore, by doing this the distributor timing will be knocked back 16* and will be near where it should be. My opinion.... I would have checked both inlet and exhaust timing events during the initial assembly __________________ Unfortunately, two half wits don't make a whole wit!