Another distraction. VAX Interceptor discovered in a barn!

My barn. Some parts that I bought back around 1975 or so have been identified as the most important parts of a very rare model of Royal Enfield.

When I first heard about the 1960 Royal Enfield 700cc Interceptor, I attempted to argue with the guy who told me about them. Turns out they're real. Enfield was working on the Interceptor design, and built a few prototypes using a hot-rodded Constellation engine, and shipped them to the US in 1960, two years before the formal introduction of the 750 Interceptor.
According  to the wikipedia article about Interceptors they made 163 of them. Other sources put the number at 170 and 211. According to Burton Bike Bits Interceptor Registry there are only 9 (not counting this one) known to exist, either as complete bikes or as correctly numbered crankcases or frames. Mine would make 10.
I discovered what this was after I sent a list of engine numbers for crankcases that are in my possession to the REOC-UK to help them update a database they're compiling based on factory records vs what is known to exist now.
The  following is copies of part of an email exchange I had with the REOC president regarding the engine and frame numbers that I sent to him.

Hi Carl,

Thank you for the engine numbers.

We didn't have any of the YB numbers you gave, so that's another three added to the listing.
This unfortunately also means that I cannot date or verify your comlete machine as it is not in our records - will have to assume that it is an original pair for now.

The damaged cases with a VAX number are from a 700cc Interceptor despatched in April 1960.

Your Tomahawk is even more interesting as the frame number has nothing recorded against it in the ledgers. The machines either side have similar engine numbers to yours, however, so it is an original machine although it was probably despatched in 1957, possibly '58 but definitely not '59.

As we do not have this machine in the records, I would most grateful if you could take a picture of the complete bike and close ups of the frame / engine numbers and let me have them as email attachments.

Please let me have the numbers of the frames you have as well - I can let you know what they are (hopefully) and annotate our records that the bike has been broken up.

Regards,

Graham

I was asked to send in any frame numbers that I had, which I did.

Graham, I've found three Enfield frames in my collection of parts that I
forgot that I had.

I think they're all 500 or 700 twin frames.

The numbers are 6828, 7651, and 11051.

The two lower numbered ones don't have the large plate-type head steady
lug welded to the main tube. 11051 does have one of these, plus holes
for the triangular aluminum block behind the gearbox. It has an older
style swingarm with bronze bushings and grease fittings.

I hope this is of help in completing your records. Two of these frames,
6828 and 11051 are still usable, 7651 was "re-engineered" by some
shade-tree mechanic who thought an Enfield frame would work better as a
full-cradle frame. I'm afraid that if one was to cut off the crude lump
of pipe that was welded to the downtube, it would weaken the downtube
enough that it wouldn't be safe to use the frame.

I'd love to hear what model/year these frames are from.

Thanks,
Carl

The reply.

Hello Carl,

Thank you for the numbers.

7651 is a December '58 Apache (Brockhouse).

6828 could be either a May '58 Apache (Brockhouse) or a July '63 500 Sports
Twin (Shores).
I don't know enough about these to verify which one, even with a photo of
it.

11051 is an April '60 700cc Interceptor, often referred to as the "VAX"
model, this being the engine prefix.
All these engines had 60xxx numbers, but the damaged cases you have are not
from the engine originally fitted to this frame.

Regards,

Graham

After realizing that I had some potentially valuable parts, I dragged them out into the light, and realized that I'd misread the frame number, so I sent an email with the updated number.

Graham, I've got several people who are very interested in that vax
interceptor frame, so I got it out of storage to take some pictures, and
discovered that I'd misread the number.
It's 11059, not 11051.
Is this outside of the range for a VAX Interceptor?

Thanks,

Carl

Confirmed that I had an engine and frame which came from the same bike.

Hi Carl,

Assumption correct - your "corrected" frame number 11059 was indeed shipped
with engine VAX 60219 fitted during April 1960.

Regards,

Graham

Then I got to thinking about the number stamped on the front of the same engine. I'd been told that this number represented the number stamped on the gearbox that was originally shipped with the engine as parts of the same bike.
Once again, I discover that I had a serial numbered part that came from this same rare Royal Enfield.
Another piece of the puzzle dropped into place when I remembered that I had one crankcase with no number stamped on it. This was among the parts in the purchase I made which included the VAX Interceptor. It's believed that Enfield shipped un-numbered crankcases to their dealers to install when an engine wasn't found to be repairable. They were probably expected to stamp it with the number from the original engine. This crankcase was probably the replacement for the one that was broken by a thrown connecting rod. Why the original owner bothered to keep the broken one, I don't know, but it was a good decision.
Here are pictures of the parts I have to build a VAX interceptor. All the other parts can be obtained, either from newly manufactured parts, or used parts. I have most of the engine parts that are needed.
Now I need to decide if I want a third Royal Enfield project, or if I should pass this on to someone else.
I've recieved offers.

The frame:

The engine.

The gearbox.

The replacement engine:

 

There's one more email I should copy. The REOC president said he found the factory record for my Tomahawk. It had been mis-filed in the ledger for the 700cc bikes.

Hi Carl,

I have just chanced upon the entry for your Tomahawk in the factory ledgers.
Some fool wrote it up in the 700cc book, so I have transferred it into the correct 500cc file on my spreadsheets.

It left Redditch on 28th November 1957 for the Brockhouse depot in the UK, then on to USA.

Regards,

Graham