1970 Amal Carbs - 930/46 & 930/47 difference?

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930/46 & 47 are listed as having 180 main jets instead of the 30/31 220 main jets, other than that, they appear to be identical in specification.
 
thanks LAB, so external wise do u know if they are the same thing, eg. printed with 46 and 47 on them, or are they all 30 and 31 just with different jets? what difference would a 180 to a 220 jet make? only cause im trying to do this as original as possible thanks.
 
The carb "build" number (the number after 930/) mainly indicates which combination of jets and slide were originally fitted, and the actual carb bodies will be identical externally except for the stamped numbers.

interstateOz said:
what difference would a 180 to a 220 jet make?
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180's will be weaker than 220's, but you need to determine what the correct size main jets need to be, and it's usually best to start at the rich end, and then go weaker if necessary.
 
interstateOz said:
thanks LAB, so external wise do u know if they are the same thing, eg. printed with 46 and 47 on them, or are they all 30 and 31 just with different jets? what difference would a 180 to a 220 jet make? only cause im trying to do this as original as possible thanks.
Click to expand...

The first set of mufflers I had for my '70 750 were very quiet. It ran great on 180s. The second set and the new Togas are louder and need 220s to avoid being too lean.

Greg
 
Apart from the main jet the other difference between the two specs is that the 930/30 and 930/31 didn't have the drain plug on the float bowl, which was fitted to the 930/46 and 930/47.

Amal list both specs in their catalogue jetted as: "220 with early Megga, 180 with restricted Megga, 210 with modified Megga."
 
Be aware early commando 930 carbs came with removable pilot jets and also a difference in the air screw, the removable pilot apparently was not as good as the later fixed jet, these carbs were fitted for 68 but not sure how much later.
Al
 
The only difference two Amals is that one is even worse than the other. Lose them & get flatslides.

1970 Amal Carbs - 930/46 & 930/47 difference?
 
Just wanted to say that I bought one of Jim Schmidt's PWK flatslide kits and I am very happy with both the carbs and with his after sale support.

It was hard to dump the Amals. The sad thing is that they flow very well. Their slight depression for slide engagement in the body makes for great flow but when coupled with the zinc slide in a zinc body, it makes for a short life. The design is good, the zinc on zinc was always a bad idea.

With the PWKs, idle, off idle, and coming off of trailing throttle - the bike runs much better. Much better response.
 
Thanks for the links to the anodized and chromed slides. Too late for my carb bodies though. Somehow I never knew of their availability.

Frankly, the bean counters at Amal knew, or should have known, that their decision to switch to zinc slides with the introduction of the Concentric was pound wise and penny foolish. Over the years, that decision to make the slides of zinc instead of hard chromed brass was one of the things that elevated the reputations of Mikuni and Keihin over their own.

BTW, I believe that the Concentric's design is superior in operation to that of the Mikuni VM series that have been stuck on thousands of British bikes. Too bad Amal never adequately promoted this superior alternative; as a result, they lost a generation of sales to Mikuni.
 
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