"Ray Gibbons" writes:
> On Fri, 18 Nov 1994, Lewis Dunbar Dove wrote:
>
> > Scotty,
> > IMHO, your low compression readings show that the rings have
> > not seated properly. I have always heard that you check compression
> doubts about its helping much. The rebuild was 3 years ago; if the rings
> have not seated I doubt that they are going to. If that is the problem,
Agreed. I have put over 10,000 miles on this engine. It may have had
this low compression on all those miles, hard to say. I did "break it
in" for 500 miles with 30WT, and then run 10W40 Castrol for 2000
miles, then switched to Mobil1. The new vettes are delivered with
Mobil1 fresh from the factory, having never been started. I would
think that breakin will still be something that happens on a new car
of today, but less necessary than the older vintage cars. Oil
pressure is nice and high, 35-40 at idle, 70 on the highway, after
good and hot.
> the cylinders may have been honed incorrectly. Or possibly rings were
> broken upon installation or shortly after startup (cylinder ridge not
> relieved properly, ring grooves stepped or not clean, or something of that
> sort).
Maybe. I think the cylinders where properly honed, as they were done
at a machine shop. They looked great! (looks can be deceiving?)
They cylinders where bored to .020 over, there was no ridge after that
I can tell you. The pistons and rings were new. If the problem is
that the rings haven't seated, then I agree that they will never seat.
If a ring had broken, wouldn't I see more oil consumption, or would
the oil control ring be enough to do its job?
I can tell you that the head won't be removed until another
compression check is done, and I've explored under the valve cover a
bit. There's lots of checking still to do! Removing the head is the
last resort. It would be a shame to remove it and still not find an
answer. I'm still dubious of the cam timing. I will check this with
the cover off, and do a static check.
> For example, air has to get into the engine to get an accurate reading.
> On a car with SU or Stromberg carbs is it sufficient to open the throttle,
> or must one also block the pistons in the up position? Which did you do,
> Scotty?
Duh... I put the pedal to the floor, and well, that was it. I was
thinking, I just wasn't using my brain! I will do that this weekend
for sure! (use my brain that is... :-)
Thanks for all the ideas and replys so far. I shall have news after
the weekend, hopefully good!
Cheers,
-Scotty "Righty Tighty, Lefty Loosy" Paisley
(I'm already using my brain, but is it the left side or the right?)
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