William F Daehler@DELCO on 03-12-98 02:38:10 PM
As you might have guessed I've been doing my first engine rebuild, and its
on a TR4.
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,
decarburized, and have new Deves rings on them. I had the rebushed the
wrist pins too. The wet liner sleeves have been cleaned up too. 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. My
measurements are 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 by the
workshop manual.. So what am I worried about?
I don't know what dimensions new pistons are supposed to be. Am I
observing an excess wear condition? OR are pistons suppossed to be tapered
like this and oval shaped?
I throw question this out to this. While $180 are at stake here, the issue
goes much deeper. I just can't keep on spending money just to err on the
safe side. I would like to use facts once in awhile.
Will Daehler
63 TR4 CT25340
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