Bob,
I'm not sure even slender pushrods are going to help that much. I
talked to Gerard over the phone last night and we compared clearances in
a standard 1275 block he has at his house and the tubular pushrod
diameter. The hole in the block is only about 1/16 larger than the
tubular pushrod. Would this clearance slow 20W-50 Penrite Running In
Oil drainage back into the block? Gerard also mentioned that I am
probably building up pressure in the valve cover (not vented) because
the oil is not draining back into the motor, forcing oil to go the only
place it can, down the intake valve stem on the intake stroke. This is
why the blue smoke gets worse the longer the car is running. I can vent
the valve cover, but it does not solve the problem of the slow draining
oil and I will probably still get the blue smoke maybe just a little
less. The Tubular pushrod is 5/16ths diameter and the standard stock
solid 1275 pushrod is 1/4 inch diameter. Will 1/8th inch clearance
drain THAT much better than 1/16th? That does not sound like it is
enough to me, but this is what the stock pushrod runs in a stock block.
Maybe as oil pressure drops during run-in coupled with the pressure
relief of the valve cover it might get better, but why does the oil take
so long to drain when it is filled up after an oil change? I think
after all is said and done I will probably have to abandon the 1.5
rockers and the Isky Tubular Chrome Moly pushrods and go with a stock
1.3 setup, not getting the full use of the 266 cam and ported head. Oil
pressure is pretty high in this new motor, but limiting the oil to the
rockers still does not address the drainage problem.
Mike MacLean
60 Sprite
56 BN2
Robert E. Shlafer wrote:
Very interesting, Mike.
Yes, let's see how your experiment using
the more slender stock pushrods works
out. Bet your guess on this is right.
Just a thought, sir. The oil pressure on your "new" motor is bound to be
pretty
high due to relatively "tight" clearances.
You might consider installing a MiniMania
(maybe Phil has one of these lying about at APT?) oil pressure limiting
valve. This
MAY allow you to use the thicker Isky
rods by limiting the oil entering
the head via the valve gear, without having to "return" to the machine
shop
to enlarge bores?
Cap'n. Bob '60 :{)
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