I received the following question and I'd like to pass it on to others
more qualified to answer. FWIW, I have heard that the 4 ring pistons
are not a good as the 3 ring variety, something about them being for
low compression tractor use not the TR engine. I let my machinist check
out my pistons so I've never gotten into this subject. I'll reserve my
own thoughts (until I'm enlightened by the collective wisdom) in order
to preserve the illusion that I know what I'm doing!
Bob Kramer, Austin TX
Hill Country Triumph Club
TR6x3, TR250 x3, TR3A vintage race
rgk@flash.net
> William F Daehler@DELCO on 03-10-98 03:52:46 PM
> I'm looking for a little help again. I'm trying to decide whether
or not
> to reuse my old pistons or not. The are 86 mm, have been cleaned up,
and
> have new Deves rings on them. The sleeves have been cleaned up too.
I had
> the rebushed the wrist pins too. The pistons are the old 4 ring
style by
> the way, the forth one near the bottom of the skirt.
>
> I have measured my pistons and sleeves per the workshop manual. It
takes
> a while to get all that calibrated equipment in one place, but I did,
by
> borrowing the right stuff from work.
>
> I'm in spec, but as defined by the work shop manual. The sleeves are
quite
> cylindrical, and all points are in spec. I'm nervous about the
pistons
> though. You are suppossed to take the measurements A-A and B-B
across the
> thrust face.
> A-A is on the skirt, taken just below the compression ring. Fine.
B-B is
> taken at the bottom of the skirt. Fine again.
>
> If I measure at the top of the piston, or perpendicular to the thrust
face
> (gudgeon pin circlip to gugeon pin circlip) I show 0.025" less.
But this
> is a measurement in an area that's undefined and not controlled.
>
> I don't know what dimensions new pistons are supposed to be. Am I
> observing a wear condition? Are pistons suppossed to be tapered and
oval
> shaped?
>
> What do I do? What do you know? What have you succeeded with? What
have
> you failed with? What do you recommend? Have you ever gotten into
any of
> these measurements? Do you want more information?
>
> Will Daehler
> 63 TR4
> 414 768-2170
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