[DeTomaso] Piston ring recommendation

[JDeRyke at aol.com]

In a message dated 11/14/07 1:01:14 PM, pantera at kommevalla.se writes:

> What type of piston rings should I use together with my forged pistons? 
> Plasma-moly?, moly?, chrome? cast iron?, ductile iron? What does gapless mean?
> 
Depends on where they're going. Molybdenum-filled rings break in almost 
instantly and last well but will chip if there's detonation. I really like them for 
street engines. All moly rings are moly-surface-treated only; none are solid. 

Chrome-surfaced cast rings last pretty much forever, and work in really dusty 
areas or dirt track racing, but may not fully break in on a street car for 
10,000 miles. I rebuilt a Falcon-6 with chrome rings and the engine had such low 
compression it wouldn't start on the starter- needed to be bump-stared until 
about 4000 miles showed. 
Plasma-moly is a way of applying moly to the face of (usually) the top ring 
only using a plasma torch. 
Gapless is done two ways- first method overlaps the ends of the top ring only 
with a step so there's no straight-through gas-path. The second uses two thin 
rings with the ends staggered so again, no gap. They work so well at scraping 
oil off, cylinder wear sometimes increases with their use. One friend ruined 
a block in one season of racing from massive bore wear. 
Cast iron is good because the carbon in it provides a little slipperiness. 
Ductile iron is processed so it has its crabon in 'nodules' and flexes a little 
more than plain cast before it cracks. Most blocks including 351-Cs are 
ductile iron   Moly rings are cast or ductile-iron underneath. FWIW- J DeRyke



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