Cam bearing pinch. Are all 'STD' Silverline bearings equal?

[Who.Me?]

I went to seal up my engine case yesterday and the the rotating assembly bound up when I torqued the lower central main case bolt.

I disassembled and reassembled a few times to track down the cuplrit. It seems to be the cam bearings, but I don't understand why...

Type 1 1600DP, rebuilt to stock.

I'd pulled the engine apart after final assembly a few weeks ago, because I realised that I'd screwed up the cam backlash measurment and it was way too loose.

During that assembly; the crank and that cam had turned freely.

I found a NOS cam with a gear that gives the correct backlash and reassembled everything yesterday.

I fitted a new set of cam bearings as a precaution because I'd damaged the thrust surface of the previous set during dissasembly.

When I tightened that lower central main case nut however, it bound up.

The previous set of cam bearings were standard sized - provided by the company who did the case work. They are marked 9796COA, 3089D STD.

I bought a replacement set of 'STD' bearings. The replacement set are marked 9796COA, 3951F STD.

I've swapped out the central pair of the new bearings (3951F) and replaced them with the pair from the old set (3089D). The cam turns freely again when I torque that central lower bolt, so there is something different about the new 3951F bearings.

I can't find a website for Silverline bearings, or a size chart for the cam bearings online.

Does that central part of the reference 3089D/3951F signify that they are actually different sizes, even though they're both 'STD', or should they both be identical? I guessed that central part of the reference was a batch number.

Am I OK mixing and matching the bearings - using the central pair from the '3089D' set and the new thrust and narrow (cam plug end) bearings from the '3951F' set? The central 3089D bearings are fine.
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Andy


Looking for info on my truck's history. Are you from Campbell California or nearby. Do you recognise it? ... http://www.thesamba.com/vw/forum/viewtopic.php?t=636786

[modok]

I don't know.

There should be no problem mixing bearing shells, even different brands.

[Who.Me?]

Thank you.
_________________
Andy


Looking for info on my truck's history. Are you from Campbell California or nearby. Do you recognise it? ... http://www.thesamba.com/vw/forum/viewtopic.php?t=636786