Hey guys. My question pertains to the intake centerline of a certain BBC cam. This spec is not listed on the cam card, so I have taken it upon myself to find the intake centerline through mathematics.
The cam we are dealing with:
Single Profile Cam -
4* Advanced
Advertised Specs -
280 Duration
.323 Cam Lift
.565 Valve Lift (1.75 rocker ratio)
Intake Opens 30* Before TDC
Intake Closes 70* After BDC
Exhaust Opens 70* Before BDC
Exhaust Closes 30* After TDC
60* Overlap
Specs @ .050"
232 Duration
6* Overlap
Intake Opens 6* Before TDC
Intake Closes 46* After BDC
Exhaust Opens 46* Before BDC
Exhaust Closes 6* After TDC
The way I'm figuring is that the centerline of the lobe should be at exactly half the duration of the lobe:
280*/2=140* OR 232*/2=116*
To find the exact center from TDC, I then subtracted the amount of degrees before TDC that the intake opens:
140* - 30* Before TDC=110* After TDC OR 116* - 6* Before TDC=110* After TDC
Now, add in the 4* advance that is ground into the cam:
110* - 4* Advance=106* Intake Centerline
By the above mathematics, I get a 106* intake centerline. Did I do this correctly?