Cliff,
Same thing happened to my rebuilt TR250 motor many years ago - a couple of
lobes on my reground Isky cam worn near round after only 12,000 miles.
Turns out soft lifters were unfortunately common back awhile and made short
work of the cam. I'm in the process of rebuilding it, using nitrided
lifters from APT in Riverside CA. I am not sure if Isky hardens reground
cams, at least at the time I had mine done. Most cam regrinders do this
now.
I did not see any mention of a crankshaft grind. Just putting new bearings
in a run-in motor makes no sense. How did the PO know what size to
install?! I can't imagine a machine shop doing this. Could very well be the
culprit for the bearing wear you mention.
Sizing pistons to the bores is another critical part of engine rebuilding.
Again, if they were installed without any work to the cylinders then the
condition you state is not surprising. Over time cylinders develop a slight
taper that needs to be corrected if too severe before fitting new pistons.
I'm looking at cams myself, but I think it best to let those listers that
have recently bought a regrind to let you know what they think. Sources for
street cams include APT, Isky, Goodparts, Triumphtune, Elgin, Piper, Kent,
TSI, British Frame and Engine, and PRI. Some only do regrinds. The one
thing I'll say, though, is that they are all as helpful as can be and are an
absolute pleasure to deal with.
As you may know, though, going the high lift cam route may require that you
line bore the block for cam bearings, install better valve springs and
tubular pushrods. It should not be necessary if you keep the lift to a
modest increase from stock. Except for a modest compression increase and
0.040 over pistons my motor was stock except for the Isky Z-19 grind. And
make sure your compression ratio matches the performance level of the cam if
the CR was or will be modified.
Chalk it up as a learning experience and do some research before you move
forward. Besides the listers' personal experiences there are many, many
websites devoted to TR six-cylinder performance modifications.
Good Luck!
Greg
CD6250L
Chapel Hill, NC
----- Original Message -----
From: "CLIFF DAVIES" <c_davies@sympatico.ca>
To: <6pack@autox.team.net>
Sent: Monday, March 10, 2003 10:47 PM
Subject: Motor rebuild Can this be ?
> I just completed a tear down of my engine, much to my surprise there is
> significant
> wear. The cam is toast, lifters too, a couple of main bearings have wear
to
> the copper, big rod
> bearings some have scratches, pistons have evidence of scratching on
thrust
> sides. Cylinder walls
> don't look bad at all, but I'll wait for the machine shop to look at it,
same
> with the crank.
> So all of this bad news inspired me to dig up the old bills from the PO's
PO.
> In 1988 the motor was...
> I'll say refreshed, new pistons, rings, reground cam, lifters, head job,
all
> bearings, sprockets and chain
> oil pump, water pump, tranny, clutch .. on and on. The motor alone was
$3,200
> Canadian in 1988. No rebore or hone??
>
> Now here's the thing. There was 68,000 miles on the cars odometer the year
it
> was rebuilt today it
> has 85,000. Why so much wear in only 17,000 miles? I am almost certain
there
> was no tampering to
> the odometer. Any ideas? Maybe the PO's Mother was racing it?
>
> Cam question I was going for the BPNW regrind version of the Piper 270.
Now my
> cam has no core value
> and was wondering should I get a regrind at all ? I want a little
performance
> upgrade? where is the
> best value coming from these days?
>
> Cliff
> 73 TR boxes full parts
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