Cam bent or case warped?

[Glenb]

Trouble now with reassembly of a T1 1600 case using original stock crank and Mahle (stock size/grind) cam that worked well together before the disassembly.

Align bored case and shop provided corresponding Silverline bearings for ground and polished crank. I was told cam was polished and in good shape so instructed to purchase Standard size bearings for cam. I purchased Silverline standard size double trust bearings for the cam. Cam end play is seems good at .003”. Everything good until some tightening of the main studs. Noticeable resistance at 15 ft lbs and then quite difficult before 20. Same situation with or without 14 ft lbs of the perimeter nuts.

Crank only (without cam) the mains take 25 ft lbs and still turns easily. Then cam alone is where issue occurs. I reached out to the machine shop and learned the cam center saddle is sometimes out so was referred to an older VW mechanic known to have a bore tool for this cam saddle. I took the case there and went through that process, with expected shavings, but to no avail. Same issue with that mechanic’s spare set of single thrust bearing attempted.

Back home I remounted a case half then removed the middle cam bearing to check for warp on the corresponding area of camshaft and found no movement from the dial indicator during rotation. Adding the crank back to the mix on the case half I did find turns well as long as timing marks are aligned but if I set the gear teeth to random positions the cam will want to walk out at specific spots of the rotation. Of course the engine would never run with incorrect timing position between the crank and cam gears.. but is this a sign that one or both is bent? Or possible indication the case is warped, etc.?

[Pruneman99]

Take the silverline double thrust bearings out, and throw them in the trash.

Then go find something Malhe double thrust, install, and smile.

I messed around with 3 different sets of the silverline double thrust bearings before gave up. It was like each half bearing was 50.1% of a circle. When you tightened the case, the bearings went all taco shaped and locked the cam.

[raygreenwood]

I have no experience with the silverline bearings....

....but dig through this and pay attention to the section about crush points, warpage and especially the chamfer o the inside side of the thrust bearing bores.

https://www.thesamba.com/vw/forum/viewtopic.php?t=694420

My finding has been that...at least on type 4's...since teh factory never used a double thrust bearing...they didn't bother to chamfer as much on the side that is unused....and also different bearing brands and makes have a different radius where teh flange is pressed that may not fit the chamfer of the case

Ray

[Chickensoup]

sorry, i didnt read all of it, but the silverline double thrust cam bearings have tabs on both thrust shells. one needs to be filed flat.
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[Glenb]

[Glenb]

[Glenb]

[Glenb]

Thanks again everyone for your input! The suggestion from Pruneman99 worked for this situation.

Was still able to install double thrust cam bearings as planned. The solution was to remove the Silverline cam bearings and insert Mahle double thrust cam bearings instead. Ends up the cam is also Mahle so not a surprise they play well together.

Now spins well at proper case studs/nuts torque.

[Pruneman99]

[nsracing]

Learning from your experiences - nothing like it.

YOu gotta catch up w/ some posts. YOu have been here awhile.