Jake Wade

How do you calculate the seat to seat intake valve closing point when all you have is the .050 number? The intake closing point is 31 at .050.

KCS

iTrader: (20)

I don’t really look at DCR, but if I did, I would use the Comp Lobe Master catalog, find a lobe with similar lift and duration at .050”, and use the “rated duration” for that lobe. Should get you close enough.

https://www.compcams.com/lobe-catalog

Shtstr

You need to know multiple engine parts static compression ratio and valve timing events.

static comp ratio
rod length
Inlet valve close timing ABDC
bore size
Stroke length
Obviously 8 cylinder
Altitude
and boost pressure if any.

I use the Wallace online calculators for static compression ratio and dynamic compression ratio.

68Formula

Most camshafts grinds are 50* or more difference between advertised and .050" (Isky @ 48*, so there still are exceptions). If you don't know, then adding 50 will at least be on the conservative side majority of the time.

QwkTrip

iTrader: (23)

Call the place that made your cam, give them the code stamped on the cam so they can look it up, and they will tell you intake valve closing event at 0.006" lift. Then you can run the numbers to estimate DCR.

​​​​​That was a good idea thrown out earlier to reference Comp cams catalog. Close enough, it's not something that needs to be down to the gnats ***.