Original vs aftermarket fuel valves

I owned some original petcocks on my Norton which were stiff and leaked a bit. I didn't really think about rebuilding them since I could just buy some stock looking valves on eBay. After I did that it didn't take long for the regular (Non-reserve) one to stiffen up to the point that the lever was getting bent. I took it apart and gave it some lube but it just did it again. So, I decided to rebuild my original Ewarts valves.

When I got inside I found out how they are different from the new "all brass" ones available on eBay and other Norton suppliers. Here is what I found:


The taper on the original Ewarts valve (the top one) is much steeper so it doesn't get jammed in tight. I polished out some of the nicks on the handle and used super fine car polish to lap it in, replace to O'ring and it is working great.

Been there. Done that. They work for a while. Then the lube washes away. And the tapers bind. And the handles bend. Sometimes the inner taper binds so bad you have to use vice grips to remove it from of the body.
Some folks speculate that the lead in the old gas kept the tapers from binding. I wonder if there was an interference angle in the original manufacture that disappears with lapping.

Stephen Hill

I guess what I was trying to say is that the new ones with a narrower taper tend to stick and the original Ewarts do not. In the machining world tapers are used to lock things together. The Morse taper being the most common. It is a shallow taper that will lock up firmly when simply put together with a bit of force. In the fuel valve, locking up is a bad thing so a steeper taper makes more sense. I think Ewarts got it right and the new guys are missing the whole point of the taper arrangement.

I've rebuilt some of my original EW taps and they've worked fine, but not gotten a lot of use because I'm sort of afraid of them. I also got some that look like the EW from Clubman except that they're chromed and have a rubber valve in them, but they do flow like the originals, I just put a set on the other week, not sure how long they will last, but I also use ethanol free fuel. I've never been real happy with the BAP ones, they're stiff and mostly just don't look right to me although they've been working for at least 5 years now. They're rubber too.

Lapped my original brass ones in , they do not leak out but leak internal. Not real bad, just after long while stored.Rigged up some nuts, spigots and rubber caps removing the fuel lines and installing them, to keep the fuel from drooling into the engine over time. Oops just remembered , I gotta go install them now :roll:

I lapped one and it leaked (internal) as jimbo says. I used a metric O-ring which I will post the specs of this afternoon. I lapped the 2nd one more carefully with automotive rubbing compound. It seals fuel and is working good right now. Colgate tooth paste is the finest lapping compound I have used. It works on some really small things. I also hit the end of the male part with a hammer to "form" the taper of the valve body. I am not sure this helped but it can't hurt. I think taking the handle off first by driving the pin out would be a good idea as well then you could spin it in a drill to do the lapping.

Oh, and if hitting it with a hammer didn't make it stick in it's taper then it is not going to ever hang up for that reason during normal use. I think if you hit the aftermarket one you would never get it out of the valve body.

The other reason I didn't use my originals is they didn't have the lock nut on the tank end and are too short to put one on. So they end up tightening on the tank where ever they end up, which means the levers are not to the outside but skewed.

I have one of the short thread ones and one of the long threaded ones on my bike right now. I solved the positioning problem by using the rubber middle washer and putting a lot of heavy duty Teflon tape on the valve. It tightened about a half turn from where I wanted it so I just cranked it around and let the washer take it.

"Rubber middle washer"? Here's what mine looked like, they just tightened up against the bottom of the tank. I never saw any washers. There also was no standpipe on one, I just used one side or the other as reserve, it would give me a few pints. But I never did run out of fuel, nearly every time I passed a station I filled up. Time for a break anyhow.

DogT said:

they just tightened up against the bottom of the tank. I never saw any washers.

Click to expand...

Should be....

http://bigdcycle.com/tempbooks/nor/1969_1970.pdf

PETROL TANK
.
.
000183 fibre washer.......2

Click to expand...

[7]
http://www.nortonmotors.de/ANIL/Norton% ... 023&Part=7

OK, you've jogged my feeble memory, there was a 'fibre' washer in there. But no rubber one.

Repost of EW fuel taps requested by member. Less the fiber washer. From a 69 S.