Posted By: Wedgeman
How to ID a used cam ? - 04/16/09 01:37 AM
HI guys...
Got a cam from a fellow enthousiast here on Moparts, he did not know the exact specs of it.
Now how can I identify the cam and the specs..There are engraved numbers and stamped numbers at the end of the stick.....like so:
engraved E 3312 HR 12
stamped 960084
Can you help ? it a 5.9l magnum roller cam
Dan
Posted By: 70Cuda383
Re: How to ID a used cam ? - 04/16/09 03:56 AM
I would think that once you figure out who made the cam, they will be able to look up those numbers for you.
some machine shops have a cam profiler that will measure the lobes and tell you what the specs are
Posted By: pishta
Re: How to ID a used cam ? - 04/16/09 04:44 AM
Chuck it up in some V blocks and put a dial indicator on it and a degree wheel on the end. Set your marker and dial indicator to zero on the backside of the lobe and start to turn it slowly. Watch until the D.I. hits .050 lift and then note the degree on the marker. Continue to turn until it tops out for lift in inches (do some math with your rocker ratio to find valve lift) turn until the D.I returns to .050 on the backside and then determine the degrees past. You got your duration. Valve centerline is determined from som e lobe centerline, usually around 112-118 degrees from some other point (maybe between the intake and exhaust lobes?) that I dont know. Duration is measured differently from cam manufacturers. Mopar measures them from some weird number, many measure from .050 and some measure from initial valve lift, so you can get a 312 or a 250 from the same cam depending where you start to measure duration. Eg. [Email]250@.050[/Email] is lumpy, and Demon rates their carbs on this cam spec on weather it is a street Demon (lower than 250) or race demon (over 250) performance level. Has to do alot with vacuum requirements. Rollers have a fast ramp rate. Nice for a long duration at a low lift.
Posted By: 70Cuda383
Re: How to ID a used cam ? - 04/16/09 07:47 AM
well, that would work too, but isnt the lift calculated WITH the rocker ratio? so if the cam lobe has "lifted the lifter" by .050" then wouldn't the valve actually be .35"? (magnum motors have a 1:7 rocker ratio)
so for .050 lift you actually want .007 lift at the cam lobe.
and yes, it's true that cam manufacturers advertise different numbers for duration, but just about all of them list the actual duration from .050 to .050.
so my comp XE275HL, comp lists the intake duration at 275 degrees, but lists the @ .050 duration to be something like 235
Posted By: Wedgeman
Re: How to ID a used cam ? - 04/16/09 11:22 AM
I was under thw impression each manufacturer had his own signature on the stick.....
Posted By: TJP
Re: How to ID a used cam ? - 04/18/09 05:09 PM
Unfortunately if it's not stamped with a name and grind # your pretty much out of luck. IE: Comp cams 268XE.
you can do as previously suggested and measure it. That will give you the measured mechanical properties but won't neccesarily tell you everything you need to know IE: how steep the ramps are, what type of spring pressure is needed, and what's it's intended use was. Lot's of variables. Sorry wish there was a better answer, if there is I'm all ears
Tim
Posted By: polkat
Re: How to ID a used cam ? - 04/18/09 05:33 PM
Your math is a little bit off. At .050" lift at the cam with 1.6 rockers, the valve lift would by .080", or with 1.7 rockers valve lift would by .085"
I ran into this problem a few years ago trying to ID a Ford cam. About the only thing you can do if there are no stampings or casting numbers is to determine cam lift and search through the catalogs to try and match it. If you have the right instruments and knowhow, you can figure out duration and such, but it's not alwqays accurate. And even if you have some kind of markings, they will rarely indicate the manufacturer.