I've put my engine numbers into Patrick Kelley's and KB's calculator and the DCR number's are no where near each other. The KB uses intake valve closing point at .050" lift + 15 degrees and Patrick Kelley's uses the actual intake valve closing point (my cam card uses at .006".) They differ by more than 1.6:1!!??
My engine info :
bore : 4.030
stroke : 3.25
rod : 6.25
head cc : 69
piston cc : 3.25 dome/pop up
head gasket : .039
head gasket bore : 4.166
piston to deck clearance : .020
Cam :Speed Pro CS1062R
Duration at .006" Int/Exh 304/287 deg ITC 78 deg
Duration at .050" Int/Exh 220/231 deg ITC 36 deg
Gross Lift Int/Exh .312"/.320" with 1.6 rockers
LSA : 110 deg
Intake centerline 106 deg (calculated from midpoint of opening and closing points)
Questions : 1st, which calculator is correct/more accurate?
2nd, am I missing something on my cam card or could it be incorrect? I ask because 42 degrees of crank rotation seems like alot of degrees for the intake lift to go from .050" to .006". And, according to the cam card there is more intake duration than exhaust at .006 lift, but vise versa at .050 lift. If my card is accurate, then that is ONE LOW ramp rate between .050 & .006 for the intake, and the ramp rate is a fair amount faster for the exhaust lobe in the same range. I checked a bunch of other cams and could not find one where the int duration was greater than the exh at .006" and then lower at .050" lift.
3rd, how low can the DCR be before issues develop?
FYI - I did not degree the cam when I installed it.
What do you think?
As always, all help and advice is greatly appreciated - Jim