> Our group disassembled his motor last weekend and found a lot of carbon on
> the valves which is understandable with the oil usage.
Is the carbon only on the combustion chamber side of the heads ? Or is it
also underneath the head and on the exposed part of the stem ? If it's
underneath the heads of the intake valves, then you've also got bad valve
guides, and possibly too much oil getting to the rocker area.
> I seem to remember the ring gap
> should have been 0.012 to 0.018.
I don't have a TR6 manual handy, but even that sounds large for a stock
motor. Usual is more like .006 - .010.
> Talked to Ken Gilanders and
> he suggested that we should measure the piston to cylinder gap
Good idea.
> He thought that 0.006 piston to cylinder
> gap at the
> piston skirt would be optimal.
That's appropriate for a race motor, but a street motor could be a smidgeon
tighter, maybe only .004" or .005". IOW I wouldn't bother trying to fix
it, if you only measure .004".
> In looking in two motor manuals, there was a reference to a Class A and
> Class B cylinder diameter
The difference between those will be very tiny, less than .001". Basically
you can ignore the difference at this stage.
> but no specs for 0.010, 0.020 diameter
> tolerances.
Just add .010" or .020" to the standard diameters given.
For that kind of oil consumption, you're not looking for a .001" or even
.002" error, it's got to be something huge. The .025" ring gaps might do
it, but I'm guessing there's something else as well.
Was this an amateur mechanic that installed the rings without checking the
gaps ? Or is there a professional somewhere we should be avoiding ?
Randall
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