I just converted a "stock", 455 points distributor, to a Cam Sync for EFI and Coil Near Plug. I have to install a bronze cam gear, because of my roller cam, but need to know how much end play or play in general, is OK for a distributor? Thanks, Gary G.
I would not worry about end play too much. The distributor sees a constant load turning the oil pump. Its not like the drivetrain that sees loads on both sides of the gear- power or a coast load. There is no "coast" load in the distrbutor. As long as its not crazy loose I would run it. The shaft won't be moving up and down. It'll be pulled tight the whole time it's running
Make sure that a bronze gear is ok to use on a roller cam. My TA roller cam requires a hardened distributor gear.
X2, I have been using a hardened gear from TA with my hydraulic roller cam for 8 years now. I believe Dave Ray (The Ignitionman) used to set them up pretty tight, .012-.015" if i remember correctly.
we run the 350 probably the hardest of anybody(any 455's?) out there and when it comes to dist/cam gear wear. (i have my gears polished and treated)we run 60-100 psi oil pressure. all this brings gear wear. it also brings timing cover stretch! all the parts create stress on the t/c. doing a rebuild this past winter i found the dist wobbled in the hole. enough to make gear wear an issue despite metal finishing the gears. you may not see it, but its there. had to build a new t/c for the 350. just when you think you got it down pat, it throws you a curve.....
Yup, no more then .015" is needed even with a Aluminum body distributor, if you need more to not show ware then something is up!
I got this from Schurkey (I was hoping he would hop on here): "Chevy, Cadillac, and Buick spin the distributor CW. Distributor thrust is UP. Therefore, they have thrust washers between distributor gear and housing. Olds and Pontiac spin the distributor CCW, so distributor thrust is DOWN. Olds has a cast pad in the block that takes the thrust. I don't know about Pontiac. Gonna have to find out. IF you're going to tighten the thrust clearance, you must leave at least 0.010 clearance. The aluminum housing expands when hot, you need to leave room for the housing to grow because the steel shaft won't expand as much. Adding shims to take up clearance in effect makes the distributor housing longer. Make sure you're not binding-up the oil pump or you'll score the plate at the bottom. When the distributor is installed and tightened down, you MUST be able to lift the rotor (and therefore the entire distributor shaft) at least 0.010 I asked about an HEI, but I think the same applies to a points dizzy: I don't think it matters a stinkin' bit. The drag of the oil pump acting on the helical gears should assure that the distributor shaft is pushed "up" any time the engine is running. Hold the distributor in your hand. Push the gear and shaft all the way up. Does the reluctor still align nicely with the pickup coil? The reluctor doesn't sit with it's teeth higher than the teeth of the pickup coil? If that's true, shimming is optional. Again, if you shim--you MUST verify that there's still ~.015 clearance when the distributor is installed and torqued down. You'd check that by putting the distributor in, and then lifting on the advance mechanism to verify some play. You MUST have some up-and-down travel of the distributor shaft. No play--too many shims--no clearance--excess wear on oil pump and distributor thrust washers."
