A coat of paint probabily doubles the strength of the rubbish that amal cast the carbs in. Zinc or a white metal alloy used to get the maximum life out of the dies the carbs were cast in, no thought given to the life of the carb (supposedly 10,000 miles in the case of a concentric)
You could not be more wrong if you tried .
Amal use the said same alloy as all of the carb makers used to and still do today.
Melt down any modern carb and you will find it is the same alloy
It is used because it is the best alloy for the purpose and can give a mould detail retention in the order of .ooo1". Fine detail retention and accurate sizes are exactly what you want from a carb.
Back when they were new & we rode our bikes daily they did not give any trouble because they were designed to be lubricated by petrol vapour being adsorbed into the oxide layer. Now that our bike are toys we haves problems because we ride our bikes once a month ( if that ) and the carb dries out.
The only big problem with the concentrics was the flange distortion which can be eliminated by using a soft washer against the carb and tossing the O ring .
The O ring was a specification of the bike companies not Amal, Enfield did not use them and when was the last time you heard a Connie or Inter rider complain ?
As for only being good for 10,000 what a load of total shit.
I would have put up well over 50,000 miles every year, year in year out and all I ever replaced was slides about every two years and needles with needle jets at about the same frequency as points.
The 626 on the M20 had done well over 40,000 since I put it on in 2001 and it came off the B40 where it had been for 8 years and about another 20,000 miles.
It got a new No 2 slide co I could could cut the correct cut away ( ended up at about 3& 1/4 ) and a couple of needles till I got the tune where I wanted it.
I have changed the needle twice and the slide once & it is still going strong.
There is absolutely nothing wrong with the alloy of an Amal just with the idiot moron journalists who have no understanding of foundry metallurgy and write shit in magazines that gets repeated by more riders with no understanding of metallurgy till it finally becomes a totally incorrect "fact".
You can trace all of this back to an article where the "writer " ( I can not call him a journalist ) overheard the foundry men calling the alloy "pot metal " and this twit actually wrote that they were made from "old pots" where as the type of furnace used in die casting is called a "POT" thus any metal that goes in it gets called "pot metal" regardless of weather it is zinc, lead, tin , or bismuth based alloy.
