Here is the setup; New main babbitt in block and caps, new crank gear, reground cam, good cam bearings.
For 1/2 revolution (one full rev of the crank gear) there is no issue then after that the crank gear starts making small tick marks on the front edge of the cam teeth. About the middle area of that 1/2 revolution it want to bind up for about 10 tooth's. Like it's out of round with a bump in the middle for half a turn.
Put the old iron gear back on, no real issue with it.
Has there been any reports of anything like this?
I don't know the source of this gear as it is a project started two owners back, I am just doing the work. I don't think the guy that started this and bought the parts is still around.
There could be 4-5 things causing problem you describe. Runout or wobble of the cam gear or crank gear-both could be caused by a variety of things. You don't mention how much backlash you have when you can turn things, but I suspect not much. The fact you can install a worn cam gear and turn the engine over means little. Your cam could be bent, the cam nose could be running out- either radially or axially, the crank nose could be running out due to an incorrectly ground crank journal, the cam/crank center distance could be incorrect, or you could just have a poor quality or damaged cam gear. My suggestion is to check these things one at a time until you find the problem. You should have .004"/.006" backlash all the way around the cam gear and it should not vary more than .001/.002". Dan
Sounds like the bore of the gear is not centered. This can be checked with a caliper.---Len
Good news, operator error! I reinstalled the gear and found that it was not fully seated the first time. I did not mark it but think I put it 180 to what it was and now is fine.
Mark, if it is 180 degrees out isn't that a problem for timing? Or do you just rotate the timer contact as well? I'm not sure but am curious.
Makes no difference, 2 revolutions of crank to one of the cam. There is no 180 out option with crank/cam timing.