Re: The Aging of SU Carburetors

[mikeh@dist.gov.au (Mike Hutchings)]

     Robert C. Paulson wrote:
     
"The pair of HD6 carburetors on my XK motor that is in my 3.8 'S' type 
seem to be working correctly.  I'm not sure why."

Ain't it the way.  You worry when something doesn't work and then worry 
when it does!
     
"I own the Haynes SU carburetor repair manual and upon reading it I 
formed the opinion that many things rot and wear in the HD6.  Ok, but at 
what rate?"

I had my HD6's from my 3.8S completely overhauled by a shop in 1991.  I 
don't know for sure, but I paid for new everything - springs/diaphragms 
jets needles gaskets washers etc.  I then garaged the car for over four 
years.  The occasional startup etc.

Having recently put the car back on the road I needed to check out the 
carbies again.  Firstly some of the "new" parts I had paid for didn't 
look so new ( different length needles, different length piston springs, 
different coloured diaphragms, missing washers, etc).

However I did find that the bottom diaphragm springs were both half 
rusted away.  The bottom of the housing was full of rusted glug. This 
was a result of allowing water to accumulate in the carbs either by 
condensation in the carbs themselves or dragging it through from the 
petrol tanks.  I assume more regularly running would alleviate or 
considerably slow down this process.

I also found that various fibre washers were quite brittle.

I have just finished rebuilding them myself from new parts I purchased.
     
"preventive" maintenance on the carbs? If so, what type?
     
To me regular running and ensuring what goes in ie petrol and air (check those 
filters often) are as clean of foreign material as possible should just about be
all that's required.  I would hazard a guess that the fibre washers have a life 
span but can't advise what that would be.

It has also been suggested to me to swap over to a different model of SU's - the
HS I think.  I have yet to check this out.

I forgot to mention the linkages.  Which are my current source of headaches.  My
throttle linkages are in a terrible state - with some pins being more than half 
worn through, (maladjusted?).  Might be worth the occasional check also.

mikeH

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