New Amal carbs - are they any good?

[bsaketcase650]

When I started the restoration of my 60 A10 the one major part that was missing was the carb. I therefore bought a new monobloc 389, jetted as recommended, from a well known supplier.
The engine on the bike is now running a treat (having overcome my earlier ignition timing problems). However, after a very short time of running the carb floods, with petrol pouring out via the tickler. Thinking that there was a float/needle problem I have cleaned the carb thoroughly and blown all airways through with compressed air. Result - no change,  petrol still pouring out everywhere. The float appears to be fine with no hint of a puncture.
I seem to recall reading somewhere that "new" Amals are not without problems, including the flooding problem I have described. Is there a way to overcome this annoyance or would I be better throwing the carb on the back of the bench and obtaining an original monobloc 389 and refurbishing it as required. What do you think?

regards

Simon

[Caretaker]

Hi, can only speak about the new 276 I bought, which worked great for a period, then started to make the engine running very, very rich. Turned out to be a casting problem, bubbles\cracks in the carb body around the jetblock. Guess it was just bad luck, otherwise it looked and behaved superb, and the period I used it I got quite some extra power out of my a10. Could have returned it for an exchange, but never got around to sending it in, so I'll pay for another one one of these days. Some earlier posts regarding new amals are to be found on the forum.

e

[Richard]

There are some different type of float valves about one to try would be the one with a rubbery type tip this may seal within the orifice a little better than the hard plastic type.
You will have to ask around Martin Batsby (I think that is his name ) may be a source
Richard

[MikeN]

Simon,I think you have the same problem I had.
  I bought a new monobloc carb for my A10 from Surrey cycles.It works fine but when it was new it would often flood when i turned the fuel tap on,and keep on flooding until I turned the tap off and started the engine .Then it would be OK when I turned the tap back on.
 I think you have the same fault .When you push down on the tickler button Your float is sticking in the depressed position.
  Its  easy to cure.  If you take off the float chamber end cover, you will, observe a little brass spacer on the end of the float  pivot.
 On my bike it was just being nipped when the cover was tightened up.
  All I did was introduce a few thou of end float by facing a bit off the spacer on a lathe.
  You can easily do the same with careful use of a file ,or rubbing it ,end down,on a bit of emery cloth or course "wet or dry" paper. You just have to obtain a rattly fit so the float is free to pivot up and down.
 Its a bit fiddly to hold if you are going to file it.Try sticking the shank of a drill up the middle to give you a better grip.
 Of course,all new Amals  come with a Viton (rubber) tipped float needle valve so it wont be that.
  I have also had a new monobloc for a Triumph and an earlier style for my AJS.All have performed well apart from the above.
Hope that helps,Mike

[bsaketcase650]

Mike,

Thanks for the tip. The symptoms that you experienced are identical to mine. I will try what you suggest and take a few thou off the spacer.

Cheers

Simon

[bsaketcase650]

Mike,

I took your advice and so far,  it's looking good!!
Fingers crossed!

Simon

[MikeN]

Glad to hear it.
MN

[flashblack]

Reading this thread has reminded me of my monobloc i bought new a few years ago, it would flood like yours due to the float being stuck down. Only the reason for mine was protruding moulding flash on the float ( the seam around the middle of the float), which was fouling the inside of the float bowl, a quick trim was all that was needed. Otherwise the carb has been excellent, and still is.
                                         
                                                                Richie   

[MikeN]

I also wonder if the new style plastic float may get a bit "sticky" unlike the original brass one?

[Lannis]

I have no faith at all in the plastic floats in the new Amal carbs. 

The carbs themselves seem to be OK, but over a two year period I bought 6 new floats, and 3 of them leaked, sank, and caused the bike to flood. 

The dealer refunded my money for them, and opined that a bad batch have been made; others are likely still out there.

Whenever possible, I pick up an old float at a swap meet - even at 45 years old, they're more likely to be good than the new ones!

Lannis

[flashblack]

On the subject of original brass floats, i suppose any pinholes or splits could be soldered and made good as new, meaning you could then have a float for life, so to speak. Although i have never repaired a float with solder,  someone who has tried may well prove me wrong. I am now going to look out for an old brass float as i feel less plastic on a beezer is better   

                                                             Richie

[MikeN]

Richie,
  Ive never tried soldering a float, but I have tried soldering , silver soldering and welding other closed vessels and I think it could be tricky getting it to seal . As you warm it up ,the air inside will expand and you will be fighting against hot air tying to escape.Also if you did manage to blob solder over a leak you will make it heavier which could also be detrimental to float level.
 
I think there must be some specialised or skilled process in the original manufacture that overcomes this.
  i would just look for a good second-hand one.
 Mike

[A10Boy]

It is in fact quite easy to solder copper or brass floats if you get them nice and warm first which expands extra air our before you apply the solder. As with all soldering preparation is critical, and the idea is to apply the minimum amount of solder to the joint, this usually doesn't affect the weight of the float noticeably in use.