Flow Measurements on Ewarts Fuel Tap

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Hi RobSS, Although AMC took over in 1953 they were not producing Nortons at the AMC facility untill the Norton factory closed around 63 , Once AMC took over production they started to change all sorts of things from threads to finishes .I have bikes from both factories but only really regard The Norton Birmingham produced bike as a "proper " Norton . A sort of snobbery!. I am interested in the Ewarts flow experiments as I have had an odd experience of Running out of fuel on main, turning on the reserve and finding it all gone tank dry. As the tap filter and standpipe are intact I can only assume that the fuel reserve can seep through the main tap workings at just enough rate to keep my 99 ticking along ( one was tested to over 100mpg !!). Going to fit my spare Ewarts to the Atlas to replace the modern leaky tap. Have to warn son about the non reserve reserve!.
 
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Here is one that looks promising. States 1/4 Inlet; 1/4 Outlet, but is it NPT or BSPP? I am guessing the lever on the side is Reserve Function. All brass suggests good quality.
From India.

Did a flow test on this style.
260ML/minute same for main and reserve
The top of the tube for main is lnot much over 1/2" above tanks bottom
I'm going with a rethreaded 3 position DAPCO
My 63 slimline is a small tank test bed. I will attempt to rotate the rolling chassis between the 122SS, then 650SS, then combat spec atlas before going back to the original 20 engine commando CR pistons.
YRMV:)
 

texasSlick

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I do not think 260 ml/min is adequate for a hopped up 650, or a stock 750, and certainly insufficient for a warmed up 750.

If you look at my data in post #1, 260 ml/ min is not enough to satisfy the flow rate that a. 0.125" needle orifice can pass.

Many users of chopped dual Monoblocs report their engines "poop out" at WOT over 5K rpm.
They are simply running out of gas! My Atlas with the monster needle and seat that I have, pulls hard right up to 6800 rpm. Looking again at my data, I am getting 354 ml/ min with a 0.200" needle orifice.

Slick
 
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Can't you make a brass connector to the fuel
pipe that is bored a bigger hole like the ewarts fuel tap that I used to use on my Norton?
 

texasSlick

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Can't you make a brass connector to the fuel
pipe that is bored a bigger hole like the ewarts fuel tap that I used to use on my Norton?

Read Note (6) following the data table. A slightly larger bore is not likely to yield a significant increase in flow.

Slick
 
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