I got a cam reground to the specs of an Erson RV10 cam, but the machine shop didn't give me a "cam card" telling me the pertinent valve event times. All I know from the machine shop is the following:
Duration @ .050 lift = 212 intake and exhaust
valve lift = .435 intake and exhaust
valve lash is .012 intake and .012 exhaust
I am trying to figure out valve events for purposes of calculating dynamic compression ratio, and I would appreciate it if one of the more knowledgeable beings on this board could double check my math.
According to the Erson catalog, the RV10 cam has the following specs:
Duration = 254
Duration at .050 = 210
Gross lift = .435
Lobe center = 111
Advance = 4 degrees
Valve lash = .022
These are fairly close to what the cam grinder told me, so I will assume that the lobe center and duration figures from the Erson catalog match what I have.
So, a lobe separation of 111 degrees and a common duration of 254 degrees for each lobe equals the following valve events IF the cam was installed "straight up" with 0 degrees advance:
16 degree of lobe overlap ([254/2]-111)
Intake opens at 246 degrees BTDC (254-[16/2])
Intake closes 8 degrees ATDC
Exhaust opens 8 BTDC
Exhaust closes 246 ATDC
Or, calculating these events @.050 lift:
-6 degrees valve overlap ( [(210/2)-111]
is that right? no overlap at all?)Intake opens at 213 degrees BTDC (210-[-3])
Intake closes at 3 BTDC
Exhaust opens at 3 ATDC
Exhaust closes at 213 ATDC
Is that right?
Now I remember why I switched my major from physics to history...
