On 4/12/01 12:03 AM, Barney Gaylord <barneymg@ntsource.com> wrote:
>At 10:06 PM 4/11/2001 -0400, Steve Morris wrote:
>>Gotta ask this again, as there were zero responses, ....
>
>Well that was a little unusual. There are usually opinions enough to go
>around (like mine for instance).
Yep, I kinda thought so, but I got my copy back, so it did go out to the
world. Strangely, same results with the spark plug question. I sent both
out the first time the same day. Must have been a day no one was reading
the mail.
Actually, as noted in the the follow-up message, I hadn't intended in
sending out the message quite yet. It was supposed to be a more
abbreviated version, as in the later message, and have a complete subject
line. The original message (a few days earlier) was so meandering that
the questions probably got lost in my babbling. The original is pasted at
the end of this message if you missed it before.
>>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 presume you mean making contact with the top of the BLOCK.
Yep, I meant the block. The valve better be making contact with the head
each time it closes!
>>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?
>No way. Not unless you have a high lift cam of a severely shaved head
>(cylinder head that is). First measure the thickness of the head.
>Original dimension is (was) 3.187 inches. Oringinal valve lift was .355.
>I don't have a head loose to measure at the moment, but I seem to recall
>the original chamber depth being about .420. That makes the valve head
>clearance at full lift about .065 plus the thickness of the head gasket
>(about .020 compressed).
The original head measures 3.170 to 3.178 thick and chamber is about .400
deep. It is pretty carboned up, so this is a rough dimension. The head I
got from you is exactly 3.148 thick all around, and chamber is .400 deep
as measured with a scale across the chamber area (and subtracting the
thickness of the scale, of course.) Yours must have had a bit more
removed from the top than the block side. I'll measure the valve lift
when I get the head back on by measuring the pushrod lift.
Might be a broken or weak spring, but the valves all react and sound the
same when whacked with a rubber mallet. I'll get a spring compressor and
check it out better whenever I get around to rebuilding the old head.
>>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?)
>
>That thingy, assuming it's original, is a fuel separator, intended to keep
>fuel droplets from the carb throat from getting into the vacuum diaphram on
>the dizzy. It should be mounted vertically with the end connected to the
>cab pointing down, and the end connected to the dizzy pointing up.
Yep, that's the way it is installed.
>>Any suggestion for reconnecting this joint for someone who does a lousy
>job with a soldering gun? Super glue? JB Weld? Duct tape?
>
>It was originally metal line all the way through, with the tubing soldered
>to the fuel separator. If the tube has been cut, with the mating ends
>being the same diameter, a push fit hose connector will work. Some people
>cut the line there intentionally, as it makes it easy to remove part of the
>line when working on either the carb or the dizzy, but not wanting to
>disturb the other end.
The tubing hasn't been cut. It looks like a bad or broken solder joint at
the bottom of the fuel separator. It was just slipped together. Maybe
I'll give my meager soldering skills a shot at it after all.
Thanks again for all your help. I'm going away for the weekend, but I
hope to get things back together while I'm off Monday. Good seals, good
compression, clean pistons and valves, and no possible vacuum leak should
improve things dramatically. I still think the carbs are running too
rich, but I've got to get it firing on all four before I go tinkering
with the carb adjustments.
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/
_+_+_+_+_+_PREVIOUS MESSAGE_+_+_+_+_+_+_
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
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