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Re: Cam bearings and engine rebuild

To: Sally or Dick Taylor <tr6taylor@webtv.net>, tri mail lsit <Triumphs@autox.team.net>
Subject: Re: Cam bearings and engine rebuild
From: Chuck Arnold <chuck.arnold@oracle.com>
Date: Thu, 19 Apr 2001 21:04:31 -0700
Organization: Oracle corporation
References: <27067-3ADF715B-1774@storefull-285.iap.bryant.webtv.net>
Thanks Dick.  I really appreciate all the time and care you put into
responding to us listers.  I have upgraded my head and put in a 280 degree
cam and run triple webbers [my set up intent is to runt the car hard at car
club lapping days -- runs are about 25 minutes and RPMs will be above 4 and
5000 most of that time.  Did find that ARP has the con rod bolt for $80 and
probably has the bolts for the main bearings also.

As far as the cam bearings are concerned, once the engine is bored, how are
they kept in place [in my imagination with no facts to go on, I thought
these bearings to be a single bearing in the rear of the engine, now I am
beginning to understand they must be all along the cam.  If that is the
case, they must be installed when the engine is out and upside down with
pistons and crank removed [no problem, that is happening anyway].

Chuck

Sally or Dick Taylor wrote:

> Chuck---Others have told you that these bearings are listed in the major
> supplier catalogues, and were original equipment in the Mark III
> Spitfire.  So far as actually using these is more a matter of whether
> you want the added expense and how much you plan to 'build' your engine.
> It's my belief that KK advised them for engines to be used in
> competition. This would mean high lift cams with serious valve springs.
> The thought being that it's easier to replace these bearings when
> inevitable wear occurs, than to throw the block away.
> About 10 years ago I purchased a set of these from TRF. My plan was to
> rebore the block for + .020 pistons and line bore for cam bearings. The
> machine shop advised me later that their machine couldn't handle the
> 'long' block. I was not able to find a local shop that could, so
> somewhat reluctantly I put the engine back together without them.
> There's been no bad things happen because of this, but I use the stock
> cam and valve springs.  Unless you know the cam bore to be worn, or are
> going with heavy springs, the engine won't know that there's no cam
> bearings.
>
> I also use the nut-on-bolt method to determine thread stretch. If it's
> going to happen, it will be at the thread root or an area unprotected by
> the tightening.
>
> My block leaked oil after reassembly (from having it boiled and acid
> dipped) in two places. The aluminum (threaded) plug under the fuel pump,
> and the large plug (2"?) at the end of the cam. Replacing this with
> several 'stock' plugs-on-a-stick didn't solve this, and ended up with
> using a bolt that 'ran out of threads' before the head so I could
> tighten it enough to stop the seepage.  The plug behind the cam bore
> couldn't be replaced until the engine was again removed. Grrrr.    These
> kinds of snafus can get you familiar with an engine in a hurry!
>
> Dick T.
> '73

[demime 0.97c removed an attachment of type text/x-vcard which had a name of 
chuck.arnold.vcf]

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