[GOSFAST]

This question is specifically "aimed" at UDHarold, or anyone out there directly involved with the manufacturing of the cams. More specifically probably with actual grinding. We're seeing a greater amount of "runout" on the back-side (heel) of the lobes. We've always measured a .001"/.002" number, but as of late we're seeing some approaching the .003"/.004" range. Don't believe it's an issue with "lashed" cams, but am concerned how much, if any, taking the amount of oil and pushrod deflection into the equation, actually gets back to the valve using Hyd.-Rollers. May be enough to "lift" the valve at the wrong time, I can't "see" it on the dyno, however. Appears to be an "equipment" issue and was wondering how many grinders out there might be still be using the old "Nortons"? It appears more prevalent with the "lower-level" brands of cams. Can't get straight answers from the "big" guys, as usual. Thanks, Gary in N.Y.
P.S. Harold only, does the names Merkel or Reed (he used to grind B.M.'s cams) mean anything to you? If so, what happened to "John". Jack's OK.

 

[GOSFAST]

As Cam-Copier said......

Most of the problem on the cheaper cams comes because they are ground by gang-masters, 17 masters and grinding wheels on a machine. All lobes are ground simultaneously, so many seconds fast, for roughing, so many seconds slow, for finishing. Unfortunately, all those wheels don't wear at the same rate, even though they're from the same batch of wheels. This means that sometimes, when the wheels all pull away from the cam, some of the lobes are NOT FINISHED grinding, and this leaves run-out on them. Statistically, the cams were finished in the right amount of time, but statistically, EACH lobe has a 2.5% chance of not being right......
This adds up, or multiplies up......
Cams gound on CNC machines, like the Landis 3L, are ground one lobe at a time.
Any hydraulic or hydraulic cam with .004" of base circle run-out IS lifting the valve off the seat at that point. The SAE says .004" is the ramp height where valve lift occurs in hydraulic-style lifters......

UDHarold

Thank you for the reply. I have many cams in inventory from when CMC was selling direct (in plain brown boxes with their own numbering system) and plan to keep and use them in our own units. Seems there was a higher level of "quality-control" back then. They have (had) a nice product when a gentleman by the name of Harry K. and the rest of the guys we're down there. Thanks, Gary in N.Y.