> The piston rings were very tight with no end gap.
Some rings are deliberately supplied slightly oversize, in case you are
fitting them to worn bores.
> My two manuals list two different ring end gaps. My Bentley manual
> states that they should be .003" to .015", which is quite a spread.
> My Haynes manual has it a bit higher at .015" to .038".
Funny, my Bentley says only .003" to .010". My Haynes echoes this number
(on page 15), but also specifies .010" to .015" for the TR4/A. Those are
new clearances, I believe the .038" mentioned in the text is a wear limit.
The TR4 factory manual also says .010" to .015".
I'll also go out on a limb here, and guess that the original specs were for
a different ring material, and that modern rings (meaning anything made
since about 1953 <g>) should use the TR4/A specs.
> A good friend of mine
> suggests .010. He feels that tighter may cause the rings to break.
I agree, .010" is a good number unless you're going racing. Then Mike P's
suggestion of .014" would probably be a good idea, especially for the top
ring.
However, I doubt that going too tight will cause the rings to break, rather
it will cause binding and cylinder wall damage. IMO, top ring breakage is
usually due to the ring hitting the cylinder ridge, which can happen if the
engine is revved beyond it's normal limit, even if that limit is below red
line. IOW, if you've gone 30k miles without ever exceeding 4500 rpm, and
then take it to 5000, you might break a ring.
Randall
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