I have one 51mm IDA Weber that I have more or less confirmed to be a Real Racing Beat modified carb. I purchased what I thought was a normal 48mm IDA Weber just the other day.

When I received it, taking a closer look it measured 51mm at the base. It also has the fuel bowl wall machined and/or ground away to create a larger fuel area. And the black cap screws holding the auxiliary venturis in place. They also both have the threaded fitting into the fuel bowl for the oil injection. All these clues leave me to believe that they are both in fact Racing Beat 51mm carbs.

Both Webers are identical with everything except the stamping. One has H1 48 IDA 13. And the other is stamped 8k 48IDA 4R.

Anyone know why the stampings differ, or what they mean?

 

Pics for reference.

 

are they both Italian? that part is a Weber stamp, so its anyone's guess what it means

 

They both seem to be legitimate Italian Weber's by their looks. But the area where it would normally be stamped on both is blank I believe. I have to check again to be sure when I get home.