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Amal Monoblock fuel spilling fix TECH

5K views 16 replies 7 participants last post by  supercrouton 
#1 ·
So your old OR new monoblock is spilling gas when tickled, or generally flooding? When you tap the bowl it stops, but you've inspected the needle, seat, and float and see no visible problem? Here is the likely culprit.....

This was on a brand new monoblock, but the same issue can happen on older carbs that have had floats swapped.

The casting seam of the float was contacting the left cover screw boss, where shown, binding the float in the down position causing fuel to spew.


The solution is to sand/file the corresponding area of the float to eliminate the interference. Easy fix for a super annoying, intermittent problem.
 
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#3 ·
Thanks, Dan! Added to the Tech Archives. Pretty soon we'll have to just rename that the British Tech Archives.
 
#10 ·
I dealt with this recently on my 64. An easier way is to remove the gasket washer from under the fuel intake bolt (terminology?) under the banjo, and seal it with fuel sealant. This brings the float needle down, you gain about 1/16" which was enough for me.
 
#11 ·
An easier way is to remove the gasket washer from under the fuel intake bolt (terminology?) under the banjo, and seal it with fuel sealant. This brings the float needle down, you gain about 1/16" which was enough for me.
The problem addressed on this carb wasn't a matter of the needle seat, and thus the float level, being too high. The float was physically binding on the inside of the carb body in its lowest range of travel thus holding needle off its seat and spewing fuel out of the tickler. No amount of needle seat adjusting, or washer removing would have solved this issue. ONLY the removal of material from either the bowl boss or float would solve this interference issue. Once the actual issue was discovered, it took less than five minutes to sand the offending material from the float and reassemble the carb, problem solved.
 
#12 ·
...you should send the information to Amal; may be if they accept suggestions, in the future they can retouch a bit the moulds. If not, they can put it in their archives. However, I do not understand how they are not aware about it...
May be is like the Hunt magnetos for the units that touch the cover and you need to sand it down (a lot) the flange that comes with the magneto to fit; and they said to me that no one ¿? never mentioned that...c mon
 
#14 ·
...they said to me that no one ¿? never mentioned that...c mon
^^THIS EXACTLY^^ is why I don't bother trying to help manufacturers. Without exception, whenever I have run into serial defects, then take the time to report it to the area rep or directly to the MFG, I get the same line: "You are the only shop with this issue" or "No, we've not had ANY complaints of this kind from anyone but you". This is not just motorsports, I've had same responses with jobs in furniture, electronics, and fabrication. I figure this forum (which gets tons of google search hits) is a MUCH better place to disclose workable solutions.
 
#16 · (Edited)
Another defect I've seen a fair number of new Amals is the tickler pin not retracting far enough (too far into bowl at rest position) resulting in bowl overflowing. This is *with* the correct float height having been set.

Easy enough to fix but it confused me the first time.

On the ones I've fixed, the bottom of the ticker pin was split along its axis like a roll pin. It was spread near the bottom to control how far upward it would stop in the carb body. Pinched it closed a bit more so it returned a little higher and problem solved.

If I had to boil down everything I've learned from building bikes over the last 25 years it would be * CHECK EVERY DIMENSION. ASSUME NOTHING *

Jason
 
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