Well my motor problem just got worse.
I took out the pistons and no 3 indeed has a broken oil ring. The bore is
also quite badly scored, as I say I overlapped the ring when installing it,
and the sharp protuding edge gouged a nice hole in the cylinder wall for a
couple of thousand miles before finally breaking, and the piece making its
way through the slot in the piston to the sump. I can be fairly sure of this
because no 4 is also overlapped, though not broken, and has also gouged a
nice hole.
This is all quite depressing, cause my quick removal of sump, replace the
big ends, and slide in new cam, has turned into discovering I have one
trashed motor.
I plastiguaged the big ends however and they were all around .0025". A bit
on the big size, but not enough to cause the knock. I wonder where that came
from?
Anyway, it is new motor time, and there were some good events coming up that
I was looking forward to competing in. Bummer.
I think I will just put together a sound basic motor. I was wanting to do
the big bore/stroker, but from the sounds of things, I need to spend plenty
of time to ensure the $$$ involved are not wasted.
So I think it will be new .040" pistons, lightened and ceramic coat, deck
block to 11:1 comp, reground standard crank, standard rods tidied up a bit,
overhaul oil pump, my SB-3 cam and lightened flywheel, full balance, my
current ported and flowed head with std valves 3 angle cut etc, extractors,
and my current twin inch and 3/4 SUs (which work quite well). Voluntary rev
limit of 6500 and I reckon about 110 to 120hp, depending on how well sorted
I get the carbs.
The pistons in the now trashed motor are .080" and I'd love to keep to that
size, but I don't trust them. The largest new I can find are .040". I would
love to find some .060" but am not having any luck.
So basically a depressing day... but hey thems the breaks I guess.
Thanks again for your help guys..
Greg
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