[SEL] Couple questions please

[bill at antique-engines.com]

So would I.
It was actually taught at a college machine shop not too many years ago -
and in manuals it was touted as a valid way to increase piston life and
restore clearances on engines slightly worn but not bad enough to rebuild.
It was also shown that truck shops did this on new engines to prolong the
life because of the increased amount of oil held against the cylinder wall
in the knurling.
According to an older book dating back to the 60's, they would disassemble
new truck engines, knurl the pistons, cut the ring grooves wider, install
hard spacers above the rings and reassemble. They had fewer issues with
rings and pistons when doing so.

We did a small amount of knurling ourselves with good results. You can
actually run *tighter* than spec clearances with knurling.

I will not state it would be good or would work on an iron piston, (or a
non-aluminum piston), but an automotive piston from anything up through
the 70's, I'd not be a bit afraid to do it.

Bill

> I have to disagree with the knurling part of the answer. I've knurled
> pistons in car and truck engines with great results. It is not 'as good as
> new' but it is pretty close in many cases and it does last quite a while.
> The last engine I did it to was a Ford 2.8 and drove it about 40,000 miles
> with no problem before getting rid of it. (It had too many dents from my
> fellow SanFran drivers; otherwise I'd still have it)
> I'd ask a machinist for recommendations as to whether it should be done in
> your particular situation.
>
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