TOPIC: Cam Thrust washer

I may have posted this in the wrong place initially, or if it was the right place, then this is the wrong place, just seeking knowledge and guidance.


I am almost ready to assemble a 1973 750. Prior to doing the final assembly I out the cases together with the crank to insure that I had appropriate end-play; I measured .014", and I do understand that the oil pump tends to pull the crank to the right, so I'm good with this.

Next, I installed the cam and found that, when the case were snugged up, the cam was bound. I had installed new cam bushings and went with the Mk3 bushes for the timing side. I removed the timing side bushes and, in a lathe, removed a few thou from both bushings, now the cam spins well and the chain sprockets are in line; I have about .006 end-play.

Just before my smile got too wide I realized that I hadn't installed, or factored in, the steel thrust washer; I'd have to completely remove the lip on the inner Mk3 cam bush. OR can I assemble without the thrust washer; will the cam eat the lip on the MK3 bush?

Should I be using bushing 06-3020 that has a lip on one end, or go with 06-5425, no lips with the thrust washer?

Bill.

1. The magic number is 1.000 inch.
2. up to 20M3 have the outboard tach and no gear OF COURSE.
3. When the 20M3S+ engine has the gear and tapered washer and with the sprocket on the cam, you will have your basic 1.000 shaft length.+/-

All early engines up to/including 20M3s have fat diameter bushes,
200000+ use skinny bushes,
Only 200000+ engines have option for different styles of skinny bush. Any of them will work in any late engine.I have used them all and work with out problem or modification
back to 1.000 camshaft length

Dimensionally correctly made parts should assemble without mod and fit and work with a bit of insignificant end play.
Bad cams/sprockets might be a bit short due to over tightening (damaging) the sprocket your shaft will be under 1.000

Very curious to at this time have 3 cam fitment problem inquiries...one including a screw up by a "professional repair shop"
Parts in hand and a set of verniers should tell you prior to assembly what your outcome should be!!!

Any late case thickness plus 2 MKIII bush flanges should be 1.000

The replacement cam arrived today it replaced the cam I sent back to AN due to casting flaws on one of the lobes. I measured the width of the installed timing side cam bushes; I used a pair of Mk3 bushings. The installed width measured 1.00, as Dyno Dave noted.

I fitted the thrust washer and assembled the cam in the engine cases, no binding. Next I fitted the cam sprocket and snugged it best I could without the chain. Still no binding, a nice smooth rotation, and about .006 end play. I'd say that I'm good to go, thanks Dave!

I did measure the new can against the one that came out, and against a Web Cams 12a that came out of the';72 I blew up on the way home from the NENO meeting in Townsend on 12/19/15 on Rt. 495 at an indicated 105 MPH, and the new cam matched all the dimensions I measured on the other two. As I didn't have the cam that bound I couldn't measure it, but I surmise that it was defective in more ways than one.

I got my rotating and reciprocating parts back from Lindskog also today so I should have a completed engine sometime this coming weekend.

Thanks, again, Dave for your time and access to your encyclopedic information,