Cam/Block Wear Plate

[RANDALL]

Had to have block machined due to cam thrust face wearing block. I can only find a SBC wear plate/shim to make up for block machining (.030" thick). Problem is, Buick cam journal is about .100" smaller than SBC making wear plate very loose (about .100" on diameter) vs. cam bearing journal.

Is this acceptable, OK to use SBC wear plate?

Thanks in advance for your response.

 

[earlbrown]

.100" is way too loose. Are you sure a full .030" was removed? That would take some SERIOUS wear to need that much machining.

 

[RANDALL]

You are correct, .030 was not machined from block, that was the thickness of the wear plate I was advised to use (typical wear plate thickness for SBC/BBC). I made a bronze wear plate .032 thick (I would be concerned about the durability of anything thinner) and sized the O.D. to suit the cam thrust face and decreased the I.D. to suit Buick cam journal.

Thanks for the reply.

 

[earlbrown]

I would try and find out how much meat was removed from the block then. With any luck, it won't matter.

 

[RANDALL]

Checked, depth of cut is exactly .032 (ouch), I would preferred a clean up cut of something less and using shim as a "block saver". Agree, removal of 010 - .015 would not have mattered possibly moving cam lobes in relation to lifter bores.

Suprised though that I couldn't find any other experiences/recommendations re: block wear and wear plate on other V6 Buicks with a roller cam and only using a bump stop to control forward thrust.

Thanks for your reply/opinion on original shim I.D.

 

[earlbrown]

The direction of the helical cut gears push the cam against the block from fuel pump load. Normally a HV pump wears out the front cam bearing (or breaks) before searious block damage can occur. I have hear stories of undeburred tapped holes in the cam causing thrust issues.

With .030"+ of available room I'd look into one of the brass thrust bearings that have the bevelled hole for a pair of set screws. ...or just take your chebby shim and drill a couple holes in it with a countersink.

As long as you're block's bare it shouldn't be that hard to locate and tap a coupler holes for a wear plate.

Note: i've never done this on a Buick block, so right now that advice is purely academic. Spend some time looking for 'deal breakers' before the tap drills get on the clock.