Gordy,
Basic rule of thumb is the bores should not vary in taper or diameter more
than about .006". Beyond that, the rings simply can't conform reasonably.
Any ridge needs to be removed, though I have seen a set of Hastings rings
that had a top ring with a stepped groove designed to clear the ridge.
Whenever fitting new rings, the bores need to have a light honing to remove
any glazing and give the new rings a new surface to break in to. As for
scoring, the finger nail test will tell you.
The head should be checked for cracks and be made dead level, and with
today's fuel, hardened exhaust valve seats should be installed, and of
course fresh valve stem seals should go in.
Of course as you say, all this is to do a "poor man's" rebuild, and this
sort of rebuild is not recommended. This has not taken into consideration
any crack testing, big end sizing or balancing, things that are very
important.
Rich
--------------------------------------------------
From: <ggilliam@usol.com>
Sent: Thursday, April 22, 2010 12:12 AM
To: <healeys@autox.team.net>
Subject: [Healeys] Engine technicals
> For the engine experts:
>
> I am inspecting the "spare" BJ8 engine I have, and have questions
> regarding the amount of wear considered acceptable for use without
> machining. I realize there are no absolute values, just a generalized go,
> no-go evaluation. I have no idea how many miles were on the engine before
> I
> rec'd it. I also don't know it's service history, can't really see if it
> has been rebuilt or reassembled, but some of the head studs were extremely
> loose, mostly the first two on the front and rear ends, on the manifolds
> side of the head.
>
> How much cylinder wear is acceptable in terms of bore oversize and
> eccentricity?...there is very little scoring, some top end ridge.
>
> Just for arguments sake, say there is .002" variation from spec. and .001
> difference difference front to back and side to side, and the same
> comparing top of the cyl and the bottom of travel. Would just a honing and
> new rings be acceptable? I acknowledge that for max reliability, complete
> machining and
> rebuild is the way to go, but we can't always have everything
> we want.
>
> What is considered too much wear or scoring?...I don't know how to
> measure the scoring, perhaps just the drag the fingernail test? I see some
> "ripple" on the one journal whose cap I have pulled, but don't notice any
> wear on the bearing surface.
>
> As a side question, I see numbers stamped on the rod ends, such as
> 55...is this weight for balancing?
>
> Hope you can understand what I'm trying to explain and ask.
>
> Regards,
>
> Gordy
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