Matt:
Further to the cylinder head discussion I found that bronze guides are fine
but you must ream them to the proper dimension after installation to prevent
the valve stem from binding.
Don't assume your oil loss is via the guides. The O-ring guide seal must be
installed at the top of the stem with the spring compressed and seals
against the upper valve cup, not the guide. It is more likely the oil loss
is due to worn rings. I agree that seals are not particularly important and
if your guides are sloppy the umbrella type of seal might result in an
improvement. Seals are only needed on the intake valves as the exhaust
valves are subjected to positive pressure when they open.
I have had no problem with standard seats vs stellite inserts. Perhaps a
little oil consumption is not all bad if it encourages some carbon buildup
which prevents valve recession. Your choice here may depend on how you
drive. High rev., high load operation will be harder on the valves than
moderate cruising where the standard seats might never fail.
If the engine isn't run low on coolant or overheated, it shouldn't develop
cracks. I agree with careful rocker adjustments and carburetor mixtures.
The Zenith carb. is not readily adjusted and should not be too far out of
range.
Fred Pixley
Napanee, Ontario, Canada
|