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Re: MGB noise

To: Nelson Yaple <Nelson_Yaple@ccm.hf.intel.com>
Subject: Re: MGB noise
From: Scott Fisher <sfisher@wsl.dec.com>
Date: Wed, 08 Jul 92 16:05:42 PDT
Nelson reminds us of his worn out 200k-mile MGB-GT:

    The funny part to this story is the 
    car ran relatively well, did not burn oil, had decent oil pressure and 
    compression was ~120 for each cylinder. 

It never ceases to surprise me, after I fix some horror or other, just
how well these cars run when they're in awful shape.  The condition of
my head and gasket made me wonder how the car managed to run, let alone
get down the road the way it did.  (Of course, the benefit is that it
really does perform much more smartly now with the matched ports and
good compression...)

    I had a valve job done on the head about 18 months ago, where all the
    guides and seal were replaced. The head now shows wear in the Intake 
    valve guides. According to the machine shop it is due to an over rich 
    mixture.  He said it is quite common on cars with SU's.  True or False?

Hey, Danny, do HIF SU carbs ever get accused of running rich and spoiling
valves?  (Sigh...)

It can happen for one of several reasons.  The easy-to-diagnose reason
is that as a car ages, it often gets tuned slightly richer for the purpose
of improving performance.  This in turn ages the car more quickly because
the richer mixture washes the oil off the metal surfaces and permits more
wear.  (Did you put in iron or bronze guides?  Bronze guides are alleged
to be better in this regard, but I don't have any hard data.)

The other problem (alluded to above) is that if you've got the original
carbs on your '72, the floats are not interchangeable.  That is, the
front HIF carb has a subtly different float design from the rear ones
(due to the fact that on the HIFs, the fuel feed comes into the front
carb and then goes OUT of the front carb to feed the rear one).  If for
some reason you get a rear float in a front carb, it will run rich no
matter how you adjust it.  

    I'm also rebuilding the tranny. 

"Now sit right back and you'll hear a tale, a tale of a fateful trip,
 That started from this tropic port aboard this tiny ship..." :-)

    All totalled it will be around $1500 when all is said and done.  Not bad
    considering how many car payments that would be on something new.

Oh noooooo... Never never never get started on the line of thinking
what you COULD have done with the money you've spent on a Britcar.
Yes, it's pleasant now, because you're thinking that it's X many 
months of Miata payments (or whatever your fancy turns to).  But
stop NOW while you still can.  The next thing you might do is to
figure out how much you've spent all together on the car.  And that
leads to remorse over having bought this car in the first place, 
comparison to all the other cars (or other things) you could have
bought with the same amount of money, and in extreme cases has been
known to lead to (gasp) selling cars.  And since you have a Lotus
and an MGB, and are therefore a certifiable lunatic for these stupid
old cars, it's only bound to get MORE expensive because you'll surely
buy another one when these are gone.  The next thing you know you're
standing out on the street corner holding a cardboard sign reading
"WILL WORK FOR CASTROL."

As I said three or four years ago: "If I had all the money I've spent
on cars, I'd spend it all on cars."  I recommend that as the absolute
limit of introspection when it comes to car-cost comparisons.

--Scott "For what I've spent on this heap, I could've bought..." Fisher


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