DeTomaso Mailing List: February 99, Message #4

-> Thanks everyone for the replies about pistons.  I think I'll call
-> Dennis Q. and inquire to his purported .015 over pistons.  I'll see
-> what I can do.

 For a .015-over piston, the block has to be almost perfect.  Most
blocks have troubles cleaning up at .030 without leaning 'fingernail'
marks where the pistons have rocked at TDC.  Simply miking the hole
isn't a guarantee it will bore clean; some of them aren't bored
prependicular to start with, and they tend to wear mostly on the thrust
side.  You have to bore it and see, so bore FIRST.


->  And this way, just maybe, I can simply Hone the
-> cyclinders myself without requiring a machine shop to bore the block.

 Not if you're really interested in keeping the cylinders round.


-> I'm looking for opinions and recommendations.  Has anyone run the
-> Total Seal? and what were your inpressions?

 They're okay.  They're fairly expensive, and if your pistons use
narrow-type rings, they're not a good solution.  I think a set of
ordinary, quality rings, properly file fit, will do just as good in a
non-supercharged motor.  For blower work, the Total Seals seem to work
quite well.


-> One school of thought goes, if the OEM's haven't started, why
-> should you.

 OEMs used to, up into the '50s.  They used overlap rings like the CH&A
'gapless' offerings, but went away due to the expense and installation
hassle.  Modern materials and machining are good enough that gapless
rings aren't required to meet their longevity requirements.  Ring seal
isn't a big issue with catalyst cars - most modern engines run low
tension rings to lower friction, and they bleed more oil past the rings
than '60s and '70s cars did.  But the convertor takes care of it, and
the blowby that goes down into the crankcase.  Engineering is a
continual juggling act.