I'm always running into people who say they used to have an MG, but they got
rid of it because they never could get the carbs adjusted right. I always
ask them if they ever added oil to the carbs. They always answer "What
oil?". The oil damper on the SUs (or rather ignorance of) probably killed a
lot of MG sales in the States.
I've always intentionally overfilled the dampers, just for lubrication of
the piston. I always assumed the extra oil wouldn't hurt anything. Am I
assuming correctly?
Will there ever be a definitive answer to the best damper oil question??????
Bob Donahue (Still stuck in the '50s)
Email - bobmgtd@insightbb.com
52 MGTD - NEMGTR #11470
71 MGB - NAMGBR #7-3336
----- Original Message -----
From: "Mike Duvall" <duvallcom@sbcglobal.net>
To: <mgs@autox.team.net>
Sent: Friday, May 28, 2004 6:28 AM
Subject: carb oil
> I too have tried a variety of oils in my carbs. My Haynes SU workshop
> manual says to "top up the piston damper with thin engine oil grade SAE
> 20w/50 until the level is .5 in above the top of the hollow piston rod.
> On dust -proofed carburettors, identified by no vent hole in the
> damper cap, the oil level should be .5 inch below the top of the hollow
> piston rod." I think all B equipped SUs are dust proofed.
>
> I just fill the piston rod to the top and when I stick the damper in,
> it overflows and is amazingly about .5 inches from the top! I also
> have been using pneumatic tool oil. It has additives to keep the tools
> clean so I figure the slight overflow might help keep the piston moving
> freely up and down in the suction chamber.
>
> The way I read how the SU carb operates ( I imagine the Zenith is the
> same) , the thinner the oil, the richer the mixture will be upon
> acceleration. Just guessing, I would say that Marvel Mystery oil is
> the thinest followed by ATF and pneumatic tool oil. I think ATF is
> about 7.5 to 35 weight. The newer 5w/30 engine oils might work very
> well.
>
> I'm always running into people who say the used to own an MG but they
> could never get it to run right. I had one guy tell me he adjusted and
> adjusted the carbs and never could get them right. The manual says not
> to fiddle with the carbs. My guess is people would never put oil in
> their carbs.....any oil is better than none at all!
>
> Mike
> 50 MGTD, 59 MGA, 65 MGB
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