ulix,
i would not accept having my piston skirts knurled! it is a short term fix
for a long term problem. the knurling will effectivly raise metal up and
reduce the piston to cylinder wall clearance. but it is a false economy
repair. the amount of metal that knurling raises is in no way as much as if
the piston were the correct size for the bore. so technically you do have a
piston that will fit a specific bore but you now have a reduced area of
contact or suport against the bore. this repair, though it will work
initially will have a short term life compared to the correct piston in the
correct bore. also, the cross hatch pattern that is scored into a surface
to raise metal leaves a pattern of deep scored marks....right? so if you
really got on the car frequently and really enjoyed the extra ponies it
creats.............what are the chances that the wonderfull cross hatch
pattern on the piston skirt could result in a catastrophic failure? the
cross hatch pattern offers the piston skirt an area where it can develop a
crack leading to seperation and catastrophic failure. in adition, you
still are confronted with a piston that is too large for the bore up at the
top end too! excessive carbon build up above top ring could lead to a whole
'nuther boat load of discussion on skuffing and wear on the bore in a long
term aplication.
sleeving is a whole 'nuther thing to consider and the biggest problem is
remaining cylinder wall and it's ability to suport the sleeve after
instalation. that is up to a competent machinist to determine, as i an
unfamiliar with what formula will work for wall thickness of a sleeve and
how much metal must be present to suport the sleve after machining block to
accept a sleeve.
just a few thoughts on the subject?
chuck
----- Original Message -----
From Ulix Goettsch <ulix at u.washington.edu>
To: Spridget List <spridgets@autox.team.net>
Sent: Tuesday, November 07, 2000 3:36 AM
Subject: Sleeving the block on a 1380?
> Thanks to everyone who responded about my piston to bore clearance.
> Knurling crossed my mind after I posted, but after talking to Dave Anton
at
> APT today, it would require bigger rings to match the bigger bore and
would
> offer less surface area to the bore, making the pistons wear faster. Does
> anyone have experience with knurling pistons?
>
> Dave also mentioned antifriction coatings that could potentially be
applied
> thick enough. Any opinions?
>
> I also talked to the owner of the LBC shop through whom I had contracted
the
> work. He talked to the machine shop and they say they will fix the block
if
> they indeed made a mistake. So next, I have to tow the car to the shop to
> have them measure the bore and pistons. They will probably suggest
sleeving
> the block. Is this possible/safe to do on a block that is to be bored to
> 1380cc? I checked Vizard but found no info. Des Hammill suggests in his
> book to avoid blocks that have been sleeved in the factory due to
> manufacturing defects for racing use since the sleeve might break. I
won't
> be racing, but bore flex might stress the sleeves. Also I just don't know
> if there is enough room for sleeves.
> Will an even thinner wall and a thin sleeve be as strong as the wall is
now?
>
> If sleeves won't work, I would have to find another block and have the
shop
> redo bores, cam brgs, align hone the mains, etc plus potentially pay for
the
> block. That might be a hard sell on my part.
>
> Thanks for any input y'all might have.
> Ulix
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