Second attempt, replacing several lines (in ALL CAPS) which mysteriously
vanished at
time of transmission...sorry to waste time/bandwidth.
---------------Original Message---------------
>Marcus Tooze writes, "A friend said he ran his
>Midget with a straight pipe (no muffler) and it sounded great...will
>it be WAY too noisy??
(apologies for being 4-5 issues behind) As a college student a few (well, too
many)
years ago I drove my first car (64 Midget) happily with a straight pipe for
many months
after my limited financial resources were diverted to expenses other than new
mufflers.
IMHO the car was not loud (when not driven too enthusiastically), although one
of
Austin's finest disagreed. I added a muffler. (I would put a straight-through
glass
packed muffler of some sort on today, so I could at least point to something
when the
officer and I lean down to look at the exhaust system!)
I have a question--I'm rebuilding the 1500 engine in the 79 Midget (of which I
earlier complained of dribbling oil out the dipstick). Still have no real
evidence as
to what might have been the cause, except the piston-bore clearances were 6-7
mils, but
no noticable wear, not even a lip you could feel or see at top of the bore.
The theory
is that the excess clearance (spec says .003 or so, I think) plus very STICKY
rings led
to
some blow-by of combustion products, just enough to pressurize the crankcase
and force
oil out everywhere. I went for +0.020 pistons, which came from same maker as
original
pistons, thru Moss (can't remember maker, AP?), and which were all very close
to each
other (within a tenth of mil or so) in diameter.
The question: the crankshaft (reground) thrust is out of specs (now 0.018,
can't
remember spec max, but it is 0.010 or so probably) with standard (new) thrust
bearings.
I've ordered +0.005 thrust bearings, got them last night, but haven't
installed them
yet. I decided not to get the 0.015 since they might have been too tight (spec
also
has a minimum, I think) Machinist (knowledgable) says I can dimple the back of
the
bearings with a center punch to raise deformations and effectively tighten the
thrust
clearance if needed. I have about decided to do that, but thought I'd get
opinions on
the subject...Is there anything wrong with the suggestion to dimple (he called
it
knurl) the bearing back if needed?
Also, I measured the clearance as per photo in Haynes MG manual, but the
measurement
pictured is *not* between bearing and bearing surface, but between the machined
surfaces on aft fwd side of crank boss-to-which-clutch-attaches and aft side of
rear
main bearing cap. The bearings are in top half of bearing only, the bearing
groove is
terminated by the main bearing cap. I expected to be required to measure
clearance
between bearing and surface.
(...LIGHT BULB GOES ON!) I REALIZE NOW THINKING ABOUT IT THAT I SHOULD
PROBABLY HAVE
MEASURED THE MAXIMUM
clearance (crankshaft pushed aft) and min clearance (crank pushed fwd) and
subtract. I
didn't do it this way. I only measured max clearance, as (I thought) was
implied by
Haynes.
Help, what measurement is needed, please?
Confusedly yours,
Ray
-------------------------------------
Name: Ray W. James
Texas Transportation Institute
Civil Engineering Department, Texas A&M University
E-mail: Ray James <rwj4123@sigma.tamu.edu>
Date: 08/23/94
Time: 06:56:18
-------------------------------------
|