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F8E barrels and Carbs

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F8E barrels and Carbs

Post  kerabo on Wed Mar 21, 2018 8:06 pm

I have an 8E and want to fit an S25 Carb with an idle screw. After finding the carb and rebuilding it I find it's too big for my 8E adaptor Stub.
I have been told to sleeve the stub and can do that but can someone explain the Fitment on these.
Looking through the parts book I see the S25 listed for the 8E so there must be something to fit them to the barrel. Or is it the barrel without the adaptor that they fit?

Regards Ken
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kerabo

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Carb manifold

Post  piston 197 on Wed Mar 21, 2018 8:40 pm

There are 2 carb manifolds the early one used on the 6E and early 8E are smaller for the brass bodied and earlier S24 carb, the S25 came in circa 1954 and this needs the bigger diameter manifold, you have an earlier manifold which is about 1/16" too small for the S25 carb and will have a smaller hole internally than the carb, so ideally you need the bigger later manifold as there will be a mismatch between the carb venturi diameter and the internal hole in the manifold causing a slight step and turbulence in the intake even if you make a nylon sleeve so the carb ,
8E trials carbs pictured, first pic is FB trials, second pic is Norman trials carb

*fits

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piston 197
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Carb

Post  kerabo on Wed Mar 21, 2018 8:46 pm

Thanks John
So there is a manifold to fit these. It was sounding as it the only way was to make one.
As I compared them it's easy to see the smaller internal bore that even if I fit the bigger carb will still restrict it.
I will search for a while and if nothing may make one.

Regards Ken
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Manifolds

Post  piston 197 on Wed Mar 21, 2018 8:54 pm

And further to confuse things there are straight manifolds and ones that are cranked to one side,
FB never fitted the Villiers carb to the Trials machines that used the E series engine
Falcon 60,62,76 all used a clip fitting Amal 276 as shown in the first picture with a special manifold also shown in the first picture, the Norman second carb shown in the pic above also used the AMAL 276, but on the standard Villiers manifold.
The engine does go a lot better on the Amal 276 carb than it does on the Villiers instrument, i have used both
JH
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piston 197
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Carbs

Post  kerabo on Wed Mar 21, 2018 9:03 pm

I have the amal carb on my other bike but the Villiers is so simple and seem to start easier. I just don't like adjusting the idle on the cable.

Thanks for the input

Ken


Last edited by kerabo on Fri Mar 23, 2018 9:53 pm; edited 1 time in total
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AMAL CARB

Post  piston 197 on Thu Mar 22, 2018 6:54 am

i expect you have an AMAL concentric on your other FB, they are a truly awful instrument and i have never had one on a Villiers trials engine i was completely happy with.
Villiers bought the Mills patent in the 20's which enabled them to make the carb they did, AMAL bought out AMAC,BINKS, etc. and because of the Mills patents could not make a Concentric carb until the 60's and when they did it was not great 1

The carbs as pictured above are without doubt the best item for 7E/8E engine and FB fitted them from 1952 to 1957 on all of their E series trials bikes in preference to Villiers carbs, so that should tell you something

JH
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f8e barrel and carb

Post  alan67 on Fri Mar 23, 2018 9:33 pm

Hi guys i also have a nice s25 carb which i was going to fit to my 8e , i have a cranked manifold small 28.5mm o/d neck, and a straight manifold with the 30mm o/d neck , as you may know i can't fit the straight manifold as there is not enough clearance under carb and the fixing hole centers are 1mm different .reading your comments on shimming the small manifolds neck out to fit the s25, would as you say create a step, but how about cutting the neck of the cranked manifold and welding on a new neck to suit, the neck on my straight manifold measures 30.2mm o/d and 25.3mm i/d . would this be sufficient regards Alan
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welding

Post  piston 197 on Sat Mar 24, 2018 7:11 am

Unfortunately the material of the manifold will make it next to impossible to weld, it may be possible to braze it, but looking for another manifold around the autojumbles is the best answer, just slip the carb in your pocket so you can be sure you get the one that fits .
JH
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welding

Post  alan67 on Sat Mar 24, 2018 8:37 am

AHHH there was me thinking they were mild steel thanks John that's saved messing up a good manifold Alan
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Re: F8E barrels and Carbs

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