I don't see any problem at all with turning down the bearing diameter of the
larger cam cores. If you want, having the camshaft parkerized will give a
little more protection to the surfaces such as the cam grinders usually do,
but the bare metal will be just fine also if run in bearings not a bare
block. I say this 'cause all the cams should be run in bearings if they
have an upgraded lift curve. You might bear in mind that when you increase
the diameter you also increase the surface speed and also increase the
frictional loss (minute) but sitll there. The bearings surfaces will work
harden a little just as the lobes do. The cast cores are ground pretty deep
too
create the finished lobe and only the work hardening is effective in giving
the core long life.
(my opinion as usual)
----- Original Message -----
From: "Bob Bownes" <bownes@seiri.com>
To: "Brad Kahler" <brad.kahler@141.com>
Cc: <fot@autox.team.net>
Sent: Thursday, September 11, 2003 6:43 AM
Subject: Re: grinding cam journals
> I'd be more inclined to have the blocks bored out. Larger journal = more
> bearing surface = less wear.
>
> What do you go through more of, blocks or cams?
>
> Would also guess the cam journals are hardened along w the rest of the
> surface of the cam, while the blocks are not...
>
> iii
>
>
>
> Brad Kahler wrote:
> > Amici,
> >
> > While looking through our pile of good cam cores for Susan's spitfire we
have found we have a lot of the large journal cams that were used in the
mk1/2 and 1500 spitfires.
> >
> > I know it is technically feasible to turn the journals down. We have a
Paeco cam in the box that was originally a mk1 cam that has had the journals
turned to match the small journal cam. However since its a Paeco cam we
aren't going to use it.
> >
> > Susan talked with Iskey yesterday and they said they could do it but
apparently they have had very few requests to do so.
> >
> > Myself, I can't see any technical reason not to turn cam journals down.
However I'd feel more comfortable doing so knowing that others have done it
or would recommend it.
> >
> > Thanks
> >
> > Brad
> > 1957 TR3 vintage racer
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