Cam identification how-to??
Finally got around to ID'ing the cam (I think).
I put a dial indicator on the cam lobe and measured .3155" on lobe lift. The shaft was purple as well. Am I correct in assuming I've got a 280/474 MP cam???
Are these decent cams? I like the way it sounds, but I can't get it to produce any more than about 10.5" of vacuum at idle. I'm hoping it'll run better after swapping the old Torker 340 for an Air-gap.
Take .3155 x 1.5 = .47325
Or round it to .473"
You really need a degree wheel on the crankshaft to measure how much duration it is off of it's seat.
Direct Connection used to have a nice .474/274 cam back in the old days, it may be one of those.
You need to put a degree wheel on the crankshaft and record duration that the lifter is just coming off of it's seat (measured with a dial indicator on the lifter), and also try to get the duration @ .050".
To do that you will need to divide .050" by the rocker arm ratio (1.5):
.050"/1.5 = .0333"
So you will need to measure the duration off of the lobe (without going through the rocker arm) at .033" on the dial indicator at each angle on the up stroke and down stroke.
Then with lift AND duration we can better guess your cam. If you can measure the lobe centers for the intake and exhaust lobes also since you are mostly there anyway, we can have an even better guess.
Every .033" on the dial indicator directly off the cam lobe will equal .050" lift at the rocker arm, which is how cams are spec'ed.
Are you sure that it is even a Mopar purple shaft cam?
