Nitrile gaskets for concentric float bowls

Anybody try these? Real gaskets in Tennessee makes them. I would think you would want a stiff gasket to keep the float pin in place unless you lightly crimp the bowl - which I've done now and then. These are not stiff, they look about like the silicone rocker gaskets. They recommend not to over tighten the screws and use a locking agent on them. Would the upshot be not having the constant weeping around the bowl? Anything else?

Brithit said:

Anybody try these? Real gaskets in Tennessee makes them. I would think you would want a stiff gasket to keep the float pin in place unless you lightly crimp the bowl - which I've done now and then. These are not stiff, they look about like the silicone rocker gaskets. They recommend not to over tighten the screws and use a locking agent on them. Would the upshot be not having the constant weeping around the bowl? Anything else?

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Nitrile does not hold up well in gasoline laced with ethanol. Viton would be a better choice of rubber. That said I think the stock gaskets work the best.

Always the ethanol factor. I think the Arab oil embargo is over so let's get back to real gas.

I've taken the stock gaskets and put a real light schemer of hi-temp silicone on both side of the gasket, let it dry before installing them.
You get the firmness of the paper and all the sealing of the rubber.
But of course you should surface the bowls on a flat surface like a 12x12 piece of granite which you can get at and home improvement store for a few bucks.
The rubber valve gaskets are not good either. Too squishy

Guido said:

I've taken the stock gaskets and put a real light schemer of hi-temp silicone on both side of the gasket, let it dry before installing them.
You get the firmness of the paper and all the sealing of the rubber.
But of course you should surface the bowls on a flat surface like a 12x12 piece of granite which you can get at and home improvement store for a few bucks.
The rubber valve gaskets are not good either. Too squishy

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I would advise others not to use the above method. Gasoline dissolves RTV [room temperature vulcanizing] Silicone sealer. The NTSB [National Transportation Safety Board] reports are full of aircraft accident investigation reports where a mechanic reused a float bowl gasket and coated it with silicone sealer [aka RTV]. The RTV dissolved, got caught between the float needle and seat and flooded the carb. In other instances, RTV was applied to a leaking fuel line fitting.
A flooded carb won't kill you on a Norton. It will ruin your ride, though.

http://www.matronics.com/forums/viewtop ... 43d63e9230

https://www.ntsb.gov/_layouts/ntsb.avia ... 218&akey=1

It is illegal [in the USA] to use RTV or Teflon tape anywhere in an aircraft fuel system. They should not be used in automotive or motorcycle fuel systems either. They say that the FARs [Federal Aviation Regulations] are written in blood. A word to the wise.

My bad. I wasn't aware he was using it in a airplane.
I've been doing it this way for a long time.
I guess I just got lucky.

Torontonian said:

Always the ethanol factor. I think the Arab oil embargo is over so let's get back to real gas.

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Prior to the use of Ethanol, MBTE [Methyl tert-butyl ether] was used as a replacement for Tetraethyllead. MBTE & other additives found in unleaded gasoline [petrol] also affect Nitrile rubber.

I have first hand personal experience here. The use of unleaded fuel became mandatory in the USA in 1975. In 1976 I was working at a large Dodge dealership. Chrysler Corp [parent company of Dodge] issued a recall for every Carter carburetor manufactured in 1975. Other manufacturers had the wisdom to replace the Nitrile rubber seals on their products. Carter did not. The Nitrile rubber seals on the accelerator pumps were affected by the additives in the unleaded gasoline. The seal would shrink, rendering the accelerator pump inoperative. To the driver, this showed up as an engine that would move about 10 feet from a dead stop, then stall. Numerous crashes occurred, when people attempted to pull out of a driveway or side street, onto a busy main street.

We spent months repairing these vehicles. We had to remove all the Nitrile seals and replace them with items made of Viton. Viton is impervious to nearly all chemicals. It also has the advantage of being rated for use up to 400 F. Working temperature for Nitrile is only 250 F.

MBTE is also a toxic carcinogen. It is hard to remove from the drinking supply. MBTE costs about $4 a gallon, Ethonol is about $1 per gallon [in the USA]. Which do you think the oil companies are going to use???

https://en.wikipedia.org/wiki/MTBE_controversy

Guido said:

My bad. I wasn't aware he was using it in a airplane. I've been doing it this way for a long time. I guess I just got lucky.

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I never said he was. The aircraft references were made to prove that this issue is not something I've made up. Your good luck probably relates to using the RTV sparingly. That said, it seems foolish to use a sealant which dissolves in gasoline. Float bowl gaskets are not expensive. Better to keep a few spare float bowl gaskets on hand. [My opinion & worth what you paid for it]

These gaskets seem like another solution to a problem that doesn't exist. If the float chamber is lapped flat the only fuel to leak out of a Concentric is when the tickler is depressed.

I agree with Matchless a problem that doesn't exist. I use a genuine Amal gasket with no sealant or anything and have reused them at least dozen times not a problem. Make sure your float bowl is flat and float height is correct (fuel should be below gasket anyway) an that's all there is to it.