Excellent find, sounds like your dad knew the stuff to set aside. The Ford number on that 1.19 4100 should be 5752425 under the XXXX's. That should give you a I.D. number for searches, in case yours can't be read. That's back when Ford was dabbling in the short lived "Boxcar" number system. It had a pretty specific application -1959 Mercury 383 with automatic. My opinion would be the desirability lies with 4100 fans who want the largest one made, rather than the few people doing a accurate restoration of a 1959 Mercury, but both are possible. There has been some discussion of the 5752425 on the old Fe Forum, here's one link, mostly talking about a similar era Holley, but down near the bottom of the post Hawkrod supplies the application info, which is sometimes not accurate on the internet.
http://www.network54.com/Forum/74182/thread/1301231031I believe forum member Bob Sprowl did some flow testing of the 1.08 & 1.12 4100's and he found the 1.12 flows about 520 cfm, others have seen similar. I don't know if anyone has tested a 1.19, but I've seen estimates of around 560-580 cfm, so it would be a little smaller than a Holley List 1850 at 600cfm. The primary & secondary venturi and throttle bore size of the 1.19 are similar to the Holley List 1849, which is rated at 550 cfm. If you do an internet search you can probably find Bob's flow test data.
I have a 5752425 1.19 4100 and it doesn't have the XXXX's over the number, so I'd probably agree with your guess, I don't think that is a Ford feature.
Info I have in my notes on the 5752425:
Primary venturi 1.19"
Secondary venturi 1.25"
Throttle bore Primary & Secondary 1.555"
Primary Jets 57
Secondary Jets 66
Primary Booster assembly "2"
Secondary Booster assembly "6"
I don't remember if those specs were from my carb or somewhere else, if yours doesn't match I could check.
I've never used mine, I have another friend who has a 1.19 4100, who is also a big 4100 fan, and I believe he has used his with no issues.
