I remember from many years ago the reason for boring the larger hole and reducing it w/ the pin was they had issues breaking the smaller boring bits on the finishing line. I heard it first at an update seminar. SO yes, carbs were made w/o the pins. I just don't remember when as I started going to update schools in the mid 70s. According to the service manual, the pin is not used after 7HP models anyways. Must be that the passages were big enough that there drill bits fared better. FYI Tecumseh didn't want you soaking carbs for more than 15 minutes. That was from the days w/ real cleaner...

So what happens to a carb that gets a longer soaking Tom?
-br

Somewhere in the process a sealant is applied due to the porousness of the casting. I have never seen any signs of the sealant, Tecumseh just says it's there so it must be so.... The Tecumseh parts guy thought of a way to increase carb sales, I dunno. In theory, too long of a soak can remove that sealant. I look at it this way. You have a carb that went green, you drop it carb cleaner for the 15 minutes, you pull it out and realize it didn't do enough- what you gonna do? You're going to remove what yuck you can and drop it back in. Chem carb cleaners do not clean like they used to either. People seem to like the ultrasonic cleaners, but I have never gotten an answer if they do anything for a carb that has water damage- so I'm still without.