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Carburetor damper thingy

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M

MtnMGB

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I just picked up a 79 B and was going through my maintenance checklist when I got to the carburetor damper on my Zenith carb. I tried to check the oil level as stated, but didn't get any reading. So, then I read about topping it off and got even more confused.

After moving the air filter box out of the way, how and what do you remove? Is the damper assembly easily seen at that point? Can you just add oil from the top? And finally, what happens if the oil is empty and/or low?

Help and advice is greatly appreciated!!
 
The little black "cap" in the middle of your carb is the oil damper (you can't miss it, it's the tallest part of the carb). If you carefully unscrew it and slide it out of the carb you'll see it has a little cylinder at the end, that cylinder is meant to ride in an oil-filled tube within a large piston that eventually creates the guts of the carb.

On Moss Motor's site (Click Here) the oil damper is part #8 way up near the top.

I think on the Zenith's it's safe to just fill with oil that cavity that the damper rides in. Different people use different oils with varied success. Some swear by 20w50, some by Marvel Mystery Oil, some with ATF, or the oil sold specifically for the carbs.

Good luck!

[ 04-15-2003: Message edited by: aerog ]</p>
 
Aerog, thanks for your advice here, too!

I identified the cap and damper OK, but for some reason my manual says to remove the entire hollow piston to fill it with oil. I'm not sure why this is necessary and unless I hear different, I may just try to top it off for now.

Thanks for your input!
 
you may want to drain whatever is in there first unless you know what it is.
 
I agree with 78Z; don't add oil to other oil unless you know what the first oil is. I have had mechanics tell my son to put brake fluid in the carb, I have had occasion where straight weight oil was mixed with multi-weight detergent oil ( that turned into "glue" and required a full rebuild). Unless you know what is in there, get it out and start off with KNOWN oil product. I use 20W50 per my local MG shop and it works fine, but I know of others who disagree. Moss sells "dashpot oil" for $7.95 specialy designed for SU and Zenith carbs.
 
My opinion is that for a street car the dash pot oil should be of a similar weight as the motor oil you would use IF you used straight weight in the crankcase. Heavy oil slows down the carb response but makes it act smoooooth. Light oil gives quicker carb action but occasionally results in a flat spot on sudden acceleration. On a Spit racing engine I used about 10 drops of 3in1 brand oil (about the consistency of water). Bob
 
Gary,
There may be some merit to using the same oil in the dampers as in the engine if you assume that the engine & carbs are at similar seasonal temperatures, eg. lighter oil in the winter & heavier oil in the summer or a multi grade for both seasons. It might give more consistent damping operation throughout the seasons.

Race conditions require a faster response (lighter oil) than a street engine which may be throttled wide open from low rpm which a race engine usually is not.

In reality the lightest oil which gives good throttle response without bog or spit back is the one to use. The factory recommended oil is 20 wt motor oil. The special expensive damper oils are 20 wt oil. People have had success with very light "3 in 1" oil, 20-50 motor oil, & everything in between.
I personally have good results with ATF which I think is similar to 5W20.
D
 
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