Amal 376 float height

[ellis]

I have just checked the float height on my 1960 gold flash and found it to be 10mm - 3/8ths of an inch higher than the pip on the float chamber cover. There is no washer on the float needle seat so I cannot see how I can lower the fuel level in the float chamber( or should I ). I used the clear Perspex cover method to check the fuel level. The plugs are always very sooty when I check them. Any information would be appreciated .

[Peter in Aus]

Have you got a plastic float or metal (brass) if metal some one could have bent the tang at some stage, and is that level with the engine running or stoped?
Peter

[ellis]

HI Peter,

A plastic float is fitted and the bike is on the center stand and not running. Their is no washer under the float valve body so I have no adjustment there. I  am just wondering if the pip on the original cover is supposed to be the normal fuel level. I run an extended float bowl so I assumed the pip was at the dead center of the float bowl and that's where I have taken my measurement from.

[bsa-bill]

I've never checked the float level on any bikes as I think it's a bit unrealistic, the bike will not run level  surely, so the angle of the carb will alter as it travels up hill , down hill, setting it up on the centre stand also is a little bit false.

add to that I've heard the pip various in it's position on the cover (if it doesn't different down draughts are not catered for) and I don't think new carbs come with a choice of where the pip is.
Lastly I know for a fact there are different float chamber covers, I have one that when fitted has the writing on it at an angle many degrees out from others

[Peter in Aus]

Hi Ellis, Just try it with the engine running and if the fuel level is about 2/3 the way up the chamber it should be OK. bsa bill is right the pips very a bit, some one mite chime in and give a more actuate setting.
Peter

[duTch]

 
 Pete rounded me up...

I can't see how different covers will affect the float level ?

 As far as I'm aware, the nipple under the right leg of the Amal 'M' (two covers 'almost same')  is the datum for a 389, but unsure how the dot at the centre of the plastic floats is calibrated .
  I was using a plastic one on my 389 for a while until I realised it is for a 376, but in efforts to get the level right, I added a strip of brass or copper over the lug under where the float needle sits, kinda like a shim to pack it up. maybe try that?

 Regarding the clear perspex, depending on your fuel formula, it may react adversely. I tried clear perspex with the old fuel and it was ok, but the newer brew murked it up. I then tried clear poly-carbonated, not much better, and then Trevor at the plastics place did some research, and sold me some clear PVC (6-8mm?), which seems to be holding up ok after some months


 

[ellis]

Hi,
 I only made a Perspex cover so I could see the level in the float chamber. I wasn't sure if the pip on the original cover indicated where the fuel level should be. I made a Perspex cover and marked the center of the float chamber and that's where I got the fuel level of 10mm above the centerline. Probably a mistake on my part. The 376 carb is 1 1/16 with the main jet of 240 and the needle jet of 106 with the needle in the middle groove.Also I run an air filter on the bike so do I need to change either of the jet sizes.
Does anybody know the correct fuel level height in the float chamber ?. I will run the engine this coming week and let you know the fuel level results.

 Cheers ELLIS

[bsa-bill]

I can't see how different covers will affect the float level ?

although the pip is quite central it is not exactly central so the one on a slant is a little lower than the other, about 10 thou, is this enough to alter mixture - I don't know.
Both covers off 389 although I don't know the history of the dirty one

[chaterlea25]

Hi All,
Rather than a plastic or other transparent cover
I took an old main jet cover nut and drilled a hole in it
to suit some small bore plastic pipe (tight push fit), you can also remove the pilot jet cover nut and push on a plastic tube to that, (slower fill tho)
Bring the plastic tube up the side of the carb to check the level
To check the level with an extended cover either mark it the same as an original cover or bring the plastic tube up the other side of the carb, the fuel should reach the bottom of the pilot air screw hole

John

[duTch]

Quote

    I can't see how different covers will affect the float level ?


although the pip is quite central it is not exactly central so the one on a slant is a little lower than the other, about 10 thou, is this enough to alter mixture - I don't know.
Both covers off 389 although I don't know the history of the dirty one

  I was thinking more of extended/shortened bowls/covers, but the two covers I have are much the same as your (Bills) left one.
Maybe the dirty/right one are for a downswept inlet tract .
I measured them up anyway, and are as in pic.

 My left one the nipple is same distance from circumference over centre of screw holes, the other cover measures vary by about a half mm, but can't explain why the top measurement varies by ~0.8mm (not important enough).

 The 'AMAL' on my right cover is ~0.75mm closer to the perimeter than the other, which make the nipple appear to be lower.

 I initially made the perspex cover long before I heard of the tube on the pilot method, but then tried the tube method when the cover went opaque, but found it too fiddly and a need to do it repeatedly, so went back to the clear cover method, and left the clear PVC one on so I can monitor the level, and also to asses its resilience to fuel.
  The main reason why I've left it on thought is because I'm too lazy to change it- better things to do , but as it turns out, is handy because my float needle must have a slow leak, as if I leave the fuel on overnight, the level rises and floods , but under riding conditions, the level seems ok.

 phew! thinkin' I covered everything?






 

[ellis]

Hi Dutch,
Thanks for your reply, So are you saying that the pip indicates the position of the fuel level in the float chamber.

[duTch]

 

Thanks for your reply, So are you saying that the pip indicates the position of the fuel level in the float chamber.

 Yes. Well that's what I've been led to believe anyway- at least for a 389

[TassieChris]

Hi Ellis
I have just bought an A7 star twin that the previous owner removed the original twin carbs and installed a single monobloc.

I had the same issue where the fuel level was a good 12-15 mm too high in the bowl (almost at the top of the bowl) to the point where the bike was spluttering and missing whenever I tried to open the throttle under load and was carboning the plugs badly. (It took me quite a while to work out what the problem was - I eventually worked it out by turning the fuel off while riding along and after a few seconds the fuel level would drop and the bike run fine.)

I made a Perspex cover for the bowl and marked a line where the dimple on the outer cover was and adjusted the float height to that line by winding some copper wire around the float to raise the valve and lower the fuel level as there is no adjustment provided on the carby. I put some solder on top of the copper wire that I can now file down to adjust the level as required.

Adjustment is very sensitive as just a small alteration to the solder level raises or lowers the fuel level significantly - I've got it set a little bit low at the moment but intend to fiddle a bit more next weekend to get it correct.

It now runs fine however so it appears a little low isn't a big problem.

see photos attached.

I have no idea why the level was so high initially unless my carby has the wrong float or valve fitted but as far as I can see there is only one size?

Hope that helps.

Chris.

[ellis]

Hi Chris,
Great results and I bet the bike runs all the better for it. I went down a different route to lower the fuel height by levering the brass plate that the needle sits on. Started with a thin blade between the float and the brass plate levering the plate up bit by bit until I ended up with a float height at 5mm above the center line of the float chamber. Went for a ride today and as you say the bike responded much better, so I might tweak the plate a little more to get the fuel nearer the center line. Isn't life great when you can make improvements to your bike   

[TassieChris]

Yes - Glad you got it sorted.

I'd still love to know why the level on both your and my carbs were so far out though when there is no adjustment.

If anyone's got any clues I'd like to know.
I'm happy everything is now good but I don't like not knowing why.