Well, now that one's out I would say it does look like aluminum after all.
They're
all painted black but the ends have that aluminum looking colour, however, it
doesn't seem as though the ends were expanded. It is very hard to tell though,
as it's a bit mangled. Once I get back to the head I'll measure the i.d. of
the holes with my nifty new calipers from Lee Valley Tools. It is very dangerous
working across the street from that place.
Jim
TS81417
relevant earlier comments:
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>I believe the earlier (steel) pushrod tubes were a press fit. The later
>aluminum
tubes had to be expanded, much like with an exhaust pipe fitting.
>Otherwise, the aluminum tubes would fall out...
>
>Keith Edwards, who had very leaky aluminum pushrod tubes, once the head was
machined
>
>TeriAnn Wakeman wrote:
>a) what seals them at the top and bottom?
>>>> I think they are just a very tight pressure fit.
>b) anyone ever replace them with something fancy, like chrome or stainless
steel?
>>>> Yes the Factory did for the last of the TR4A heads. THey used aluminum.
ALuminum expands more when hot making for an even tighter fit to keep oil from
leaking.
>> TeriAnn
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