Cam "wear Plate"

DorianL

solid fixture here in the forum
Staff member
I am doing a retrofit roller cam swap on my 400 SBC.

I read here and there that a cam wear plate is required. The .030 plate (large washer) goes between the cam sprocket and the block and, presumably because one installs a cam button, this prevents the cam sprocket from digging into the block.

The plate also requires me to take the sprocket to a machine shop to machine the thrust surface down .030 to offset the clearance taken up by the wear plate.

This seems to be a new development. Eight years ago I swapped a roller cam into a 400 SBC and no wear plate was required there... just a cam button.

What are your thoughts on this ? Necessary ?

Best,

D.
 
What changed ? different cam mfg? updated block? maybe a later fix for a previous problem
 
From what I read this is probably a fix for a previous problem.

It seems some folks experience wear at front of block. I further read that if there’s no evidence of wear, not to bother.
 
I would find out where this supposed wear occurs, maybe do a little clearancing in that area, I would say it’s better to clearance the block for about ,080 or so
 
I think this came about from when racers blocked the oil drainback ports at the front of the lifter valley. That oil, returning to the sump, would lubricate the timing chain and gears. Without that oil there might be a lack of sufficient lubrication issue where the back of the timing gear contacts the face of the cam bore. Look at the back of the timing gear. There should be "slots" that let the oil leaking from the front cam bearing to lubricate that interface.
timing gear.jpg
 
Ooooh. So that’s what those are for !!!

On a traditional cam, the lifters thrust the cam to the back of block through beveled lobes... or to front ?
 
to the back of the block "On a traditional cam, the lifters thrust the cam to the back of block through beveled lobes"
 
I think this came about from when racers blocked the oil drainback ports at the front of the lifter valley. That oil, returning to the sump, would lubricate the timing chain and gears. Without that oil there might be a lack of sufficient lubrication issue where the back of the timing gear contacts the face of the cam bore. Look at the back of the timing gear. There should be "slots" that let the oil leaking from the front cam bearing to lubricate that interface.
View attachment 14879
index.php

That’s a cam gear for OEM roller cam, I know this from building my engine. Every parts house kept giving Gen I retrofit cam gear, mine is OEM roller with cam retainer. I kept getting the cam gear without those oil grooves! The bolt circle on these two cams is also different. The OEM roller has a smaller bolt circle, you have to be careful when ordering the locking plate for the 3 cam gear bolts. I eventually had to order the timing set and locking plate at my machine shop to get the correct part!
 
Last edited by a moderator:
Dorian you can also drill a 1/32 hole in the oil galley plug on the passenger side behind the cam gear to get oil sprayed on gear and chain! If your block had npt screw in plugs buy a new one, drill it out of the block, then install it in the block!
 
You will want to pay attention to where on the circumference you cut the slot on the distributor
housing. It's best when the slot is pointing where both gears are meshing into each other and the
ignition is timed properly.

OilingModForGear04_5229.jpg
 
the picture did not post, Im working on correcting that error
ok its working
 
Last edited:
This shows the size that I cut in my distributor. With a 10% volume increase of the Melling 10552
oil pump and all the other oiling mods that I did, I have about 20 psi at idle or 850 rpm. That's
while using a 10w30 oil.

OilingModForGear01_5221.jpg
 
You will want to pay attention to where on the circumference you cut the slot on the distributor
housing. It's best when the slot is pointing where both gears are meshing into each other and the
ignition is timed properly.

View attachment 14887
I whole heartedly agree with Rick, I would get the engine running, time it where it will run, pull the distributor, look down in the intake make a reference mark where the distributor intersects with the gear on the cam, make the mark on the intake very visible then put the distributor back in and time the engine where it will run and then mark the distributor body and transpose that down to the bottom of the distributor where the the oil channel will be located.
 
Yesterday I dropped off the cam sprocket at the machine shop and asked them to remove 0.030 of the thrust surface. Might as well do as is required tho I’m a little worried about this.
 
Back
Top