Hi gang,
Last fall several of you helped me out figuring what to do with my low
compression, oil burning rebuilt MGA. We came to the conclusion that I
probably had a blown head gasket (pretty obvious since the blow-down test
in #2 cylinder came right back out #3), and that the oil burning was
probably due to rings or oil around the valve stems (as suggested by the
PO when I bought the car.) I got a rebuilt head to swap out with mine
(thanks again, Barney) but I put off the swap until the nice fall drivig
weather ended.
Well, the sudden arrival of winter weather here in Ohio, the holidays,
and some family medical problems put off the work until this spring, and
I finally began tackling the head swap today. I didn't get done, but I
didn't break anything or run into any major problems, either! (Notice the
recent questions about the fog lamp, and something else last week, and
you will see a trend here. I was putting the job off knowing full well
that a one day job would probably last me a week, based on past
experience.)
I haven't been inside an engine since tearing down VW Bugs and a Ford
Model A in the late '60s and early '70, so I dove in with a little
hesitation. Not too bad once I got things going. The head gasket was gone
in a section about a quarter inch wide between #2 and #3 cylinder, as
expected. No damage to the head or block that a couple minutes with a
stone didn't take care of. Cylinders looked good, and the piston tops
cleaned up of their accumulated carbon build up with some work.
The first surprise was a bright thin worn edge where the #2 exhaust valve
had been making very slight contact with the top of the head. I would say
no more than .005 inches deep. Sounds like there wasn't enough valve
clearance, but is it that close with standard parts? I've seem Barney's
web page on how to grind clearance for a high lift cam, but this one is
supposedly standard. Maybe the valve was partially opened all the time,
which sure wouldn't help much!
Next surprise was that this rebuilt engine had all four cylinders
re-sleeved, and has standard pistons in it. (That is unless they came
sleeved as new, but I don't think so.) Pretty expensive work, isn't it,
unless there wasn't any material left for another oversize re-bore?
I also found the vacuum tube between the carb and the dizzy was just a
loose slip fit at the joint below that thingy in the middle of the tube
assembly (What is that thingy, anyway? An accumulator?) Any suggestion
for reconnecting this joint for someone who does a lousy job with a
soldering gun? Super glue? JB Weld? Duct tape? <g>
That's about how it stands right now. I've got the block stoned and
cleaned, and the head just about ready to put back on. Got the oil
drained, but don't have a spare filter element (I knew there was
something I was going to order over the winter!) I should probably have a
lot better performance with no compression loss, larger exhaust valves,
correct valve adjustment, and elimination of a possible vacuum leak. I'll
let y'all know how things go from here...
Steve
Steve Morris Avon, Ohio
1958 MGA 1500 Red/Black
NAMGAR #5987 BuckAyes Ohio Chapter
LoCo Brits <mailto: MGA1500@mac.com>
http://www.en.com/users/smorris/mga/
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