Well, I contacted Lars Grimsrud about this and here's his reply. (He gave me permission to post his reply but only if I added that "This is only an educated opinion on my part since I have no factual information to back it up".)
I've rebuilt over 700 of these carbs, and many of them have been original, untouched carbs. I've never seen a red "R" on any carb, and I agree with your comment that there is no way that it's a pick code for the assembly line worker to install a "Rochester" carb. They wouldn't have cared, since the Rochester and Carter built carbs were used interchangeably. I've never seen a true Rochester carb with an "R" code. It's more likely that it's an inspection stamp or an indication that the carb may have been "reworked" after some issue was found on the line.
As for
MY opinion, when I worked at Oak Systems in the late 1970's, early 1980's manufacturing cable TV converter boxes, we did something similar. If a box failed the final test, it was reworked, tested and then shipped if it passed the tests. The technician that reworked the box, stamped their inspection stamp on the bottom of the box and it was noted in the boxes history sheet that it failed the initial test and had to be reworked. We kept history sheets on every box made in case it came back for warranty replacement. This gave us a way to track problems.
I believe that your carburetor failed a test at the Rochester plant, had to be reworked, then re-tested and finally shipped to one of the vehicle assembly plants. At some point during the rework/final testing phase, it was stamped with the red R to indicate it had been reworked. Kurt has stated that it's paint and not ink, and it DOES look like the PTB ink stamps Norwood used on the firewall, so he's probably right. Either way, it's rare!
I also contend that the strange code stamped on the base plate is an indicator that the base plate itself was replaced. (This also explains why there's no date stamped on it.) The code is probably the reworker's stamp or perhaps an inspection stamp.
Again, this is only
MY opinion but Lars did agree that it made sense. But without a
LOT more carbs showing up with a red R, and/or that funky stamp on the base plate, we may never know for sure.
By the way, if you're not familiar with Lars, do a Google search and you'll find he's probably (in my opinion),
THE leading authority on the Rochester Q-jet! He even has a
WIKI PAGE!!
Ed
