Date:         Wed, 26 Apr 95 11:00:40 MDT
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         aburczyk@dres.dnd.ca
Subject:      Re: Cam Bearing Part #s

Snip
>  If someone has a fiche for the type IV <Joel?> or a parts book, maybe you 
>  could help here: The part # of the cam bearing that _didn't_ disentigrate
>  is 021 101 521. The part numbers of the bearings that _did_ fall apart
>  are 113 101 511 and 113 101 522. Since most type IV parts have an 021 
>  prefix and the 113 prefix is generally found on type I <upright fan> engines,
>  I have become suspicious that the bearings may have failed simply because
>  they are the wrong parts. "How to Rebuild Your Air-cooled VW Engine" states
>  that the type I and IV parts look the same but are NOT interchangeable. 
> 
>  I'd like to understand this failure so that I can prevent the same thing
>  from happening in the future. It's a real heartbreak to dis-assemble an
>  engine which clearly had a lot of life left in it <the cross-hatch hone marks
>  are still visible on the cylinder walls> to find a problem caused by what
>  may have been poor attention to details <looks right, who cares about the
>  part number>.
> 
>  Thanks,
> 
>  Dave
> 
I know the feeling.  I am currently rebuilding a type IV motor that I had just rebuilt 3000 miles earlier.  In this case I used the wrong pistons that had a raised crown as opposed to the ones that have a concave depression on the crown.  This increased the compression ratio to approximately 8.83: 1 (as determined by ccing the heads andcalculation at autopsy).  It was supposed to be 7.3:1.  I managed to melt a piston (#4) in doing this.  I keep it in my office to remind myself of the stupid things that I've done in the past.

As far as the cam goes, make sure that there isn't a depression in the centre of the toe of any of the cam lobes.  This caused by the case hardening wearing through at that point since adjacent cam followers rub on the same area.

I always bought my cam bearings in sets.  If the cam journals are not undersize or torn up you may be able to just swap the bearings.

A new cam is about US$70 at Webber cams (stock and mechanical lifters).  You can also send them the lifters and they will resurface them for you.

If you have a stock cam you may have to buy a new wheel too.  Aftermarket wheels come in one size and are aluminum.  The old ones were cast iron I think and came in various sizes +2 to -2 which corresponded to hundreths of a milimetre under to oversize.  The new wheels are aluminum and are designed to wear in to the proper size with running.  You have to use this super loctite on the wheel bolts too.  

Personnally I've standardized on the type IV engine so I have no type I parts.  I can see how mixups could occure in a big rebuild shop though.

Andy Burczyk
'73 bus