R66 engine and frame numbers

[R66RODENT]

Somebody ground down the original numbers on my R66, but they have been recovered through the miracle of modern chemistry. I would like to gently tap in the correct numbers. Does any one out there know the correct number punch size? Or sizes?
Thanks,
Charlie

[R68]

...maybe you should just "leave well enough alone"? That's very rare and desirable BMW, and your not likely to be able to restamp the frame well enough for it NOT to appear to be a restamp? If you can really prove that it's the frame original to the motor, so what if the frame numbers have been obliterated? FWIW, the font used on the R66 frame serial numbers will be the same as any other 1938-41 BMW frame. I'd suspect that the roundel is the early larger size?...I'd wonder if your cylinders and heads serial numbers match the motor number?...

[R66RODENT]

Thanks for the suggestion. I may just do that, but haven't yet decided. What I didn't know is that the head and cylinder #'s should match the engine number.I had a chance to have a look at those numbers, because I blew a head gasket. Will remove the valve covers and have a look anyway-at least I should be able to find the cylinder head numbers, right?
best,
Charlie

[Darryl.Richman]

The head numbers, if present, should be visible without disassembly. You should see them stamped into the visible surface just inward of the valve cover mating surface.

[R66RODENT]

Nope, no punched in numbers there, and no sign of there having been any. Only numbers I can find are cast into the lower rocker support: BMW AL G3 on the top line, below which is 266. This is the right head. These are probably foundry numbers. Maybe the left has the same markings, followed by 166. The 'revealed' engine # is 661397. I've been informed that BMW has the records for all the pre-war plunger bikes, but that the R66 records are missing. Only early # I can find on the engine is 0Z 80, right above where the engine number used to be. So it appears the bike got drafted.

[Luigi bmwR68]

Hello Charlie
this are the numbers of my R66
Ciao Luigi

[R66RODENT]

Thanks Luigi for posting that photo. It seems the numbers are not punched in very deep. I've been following the various old BMW's on the Cannonball Run. Darryl Richman was in the lead with his 1928 R52, but some kind of disaster occured today (Sept. 12). He'd been having some head gasket problems yesterday, but he was able to fix that. There's also an R62 and an R11 on the run, and both are doing well as of today.
Charlie

[DasMotorrad]

Hello,
following the pictures of my R66,original number engine and heads.
my R66 is one the first produced but following i see other numbers identical of picture of LuigibmwR68

my R66





other R66's

[R66RODENT]

Many thanks-now at least I know what the fonts are like.My bike has no numbers on the heads, nor does it seem that ever were any numbers there. All that's left of the original numbers that I can see is the OZ 80 over where the engine number was ground out. There are also some very small markings forward of the OZ80 that look like 31 Y, but they are very hard to make out, and I can't be certain.

[Luigi bmwR68]

Ciao Andrea
Since our two R66 are the first models, even your no oil tubes?
I had to put on my provisional ... there was no proper housing reinforced with the crankcase. You could see that they had tried to copy what then appeared on later models.

Visto che le nostre due R66 sono dei primi modelli, anche la tua non ha i tubi dell'olio?
Sulla mia ne avevano messi di provvisori... non c'era l'apposito alloggiamento rinforzato sul carter motore. Si vedeva che avevano cercato di copiare cosa comparso poi sui successivi modelli.
Luigi