Cap for Zenith Carbs

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Steve Douglas
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Cap for Zenith Carbs

#1 Post by Steve Douglas »

I had a few plastic caps that fit the tops of Zenith Carbs. I was told they came on new carbs when bought back in the 60-70s, also on factory rebuild engines shipped to dealers. I have only 2 pair left and few friends have asked for them, but want to keep the ones I have. They keep the gas fumes due to evaporation to a minimum, as well as keep the spare carbs clean.
Anybody have a source? I tried some of the rubber plumbing caps but they don't fit tight.
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John Brooks
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Re: Cap for Zenith Carbs

#2 Post by John Brooks »

It’s been years, I need to look up the DIN specification. They are electrical distribution box plugs used on larger electrical cabinets. The EU/DIN spec has a chart in mm in diameter then mm of depth and then material.
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Alan Hall
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Re: Cap for Zenith Carbs

#3 Post by Alan Hall »

Steve, I believe the original covers that came on new carbs were actually a thin cardboard, see photo. I suspect that a suitable plastic or vinyl cover would be made by Capplugs or similar manufacturer, but not sure how easy it would be to order small quantities, maybe McMaster-Carr would have something suitable, perhaps vinyl flange cover, p/n 9532K38 which has a 2.5 inch ID.
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Steve Douglas
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Re: Cap for Zenith Carbs

#4 Post by Steve Douglas »

Thanks for the replies, I know the B/C mirror access holes covers where the same as German DIN round electrical box covers used to keep plater and paint from the inside, and were removed upon installing fixtures, but the ones I've seen didn't have tabs. and were ribbed on the outside. The Capplug is something I'll look into. My friend who's wife has a problem with gas smells in the garage, he has been popping his air cleaners off and using foil to cover the top, but would like ones like what I have.

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Al Zim
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Re: Cap for Zenith Carbs

#5 Post by Al Zim »

One thing you need to be aware of is that the fuel does not evaporate. It Boils because the Zenith Carburetors get hot. Fuel flowing down, out of the carburetors, will enter the one cylinder with the intake valve open and possible other cylinders where the intake valve has worn out he destructive situation is that it wipes the lubricant (oil) from the cylinder. The resulting fire will probably be very expensive. You are welcome to call me 817-267-4451 al zim
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Vic Skirmants
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Re: Cap for Zenith Carbs

#6 Post by Vic Skirmants »

If its boiling, its no longer a liquid.

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Re: Cap for Zenith Carbs

#7 Post by Steve Douglas »

Al, I have never seen the fuel boil in a Zenith, maybe in Texas it does, or in my old flathead Ford during a hot weather vapor lock.
The issue with the Zeniths is that the carb throat is wet with gas, and the vent tube open to the air and the fuel evaporates over time, fumes pass thru the mesh air cleaner and into the air of the garage. When parked after a drive, let the engine cool down for a few minutes, pulling the air cleaners and putting the caps on keeps the odor to more tolerable level. A friend places the air cleaners in a metal ammo box, as they normally have gas on the inside and it will keep them clean and the fumes enclosed. An inconvenience for some, but it's always a good idea to take a look at the engine after being driven, so an extra couple of minutes is no big deal.

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Re: Cap for Zenith Carbs

#8 Post by Dave Erickson »

Liquids boil, gases don’t…. Boiling is evaporation that occurs when the vapor pressure of the liquid exceeds the pressure surrounding the liquid. E.g. you can make a liquid boil by using a vacuum pump to reduce the pressure surrounding the liquid. Or you can heat it in an open container until the vapor pressure exceeds 1 atmosphere of pressure

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Don Gale
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Re: Cap for Zenith Carbs

#9 Post by Don Gale »

Try a 65mm camera lens cap
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Don Gale
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Re: Cap for Zenith Carbs

#10 Post by Don Gale »

Drum brake front hub dust caps fit perfectly, p/n 356.41.427
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1958 356A 1600 Super Sunroof Coupe
former 1966 Euro 912 Sunroof
former 1978 Intermeccanica Speedster w/'68 912
Member Since 1983, #4039

"Nostalgia isn't what it used to be"

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