barrel casting marks

I got a spare barrel (?) with a '75 850 I bought a while ago, and am trying to confirm it is, in fact, an 850 barrel (another member on this forum needs one) the only obvious markings I can find are 'BIRCO' and '24237' - is there any way to confirm what I have? other than measuring the bore. An internet search only turned up references to 750cc Nortons, and I cannot locate (cursory glance) any other markings.
Thanks in advance, Greg

Measuring the bore is a pretty bullet-proof way of ensuring what you actually have.
Also should show how oversize it has been bored - too far and its only good for sleeving. Or scrap...

850 cylinders do of course NOT have the flange all the way around the base - the 4 through-bolts (in the vicinity of under the spark plug area of the head ) are bored to connect up with the crankcase.

Hopethishelps.

Here is a cast number on the barrel base
Regards Mike

thanks guys - that casting # ending 850 is where mine reads 24237, so I guess they are not 850's. will measure them tomorrow to be sure though. Flange is interrupted, and from the photo Brooking posted, I have an extra 2 holes 'under the spark plug area'. sorry GGRider, looks like they are 750's

The number 06-3850 is misleading. The same number was on later barrels that were machined to 750 condition- by third parties, some years ago and, recently, a very small number from Andover Norton. We found some half-finished barrels from production times and finish machined them to 750 spec where possible.

Our new barrels are now marked "ANIL" (for Andover Norton International Ltd), and can be either.

06-3850 was a pure coincindence- the 850 barrel had part number 06-3850, but part numbers were allocated under no system bar "what is the next free part number?".

I measured the bores today, there is a little rust bu cleaned them up as well as I could and got 72.9mm, so they appear to be 750's

ZFD said:

06-3850 was a pure coincindence- the 850 barrel had part number 06-3850, but part numbers were allocated under no system bar "what is the next free part number?".

Click to expand...

Just to avoid any confusion, 063850 is the barrel casting number.

The part number of the finished 850 component was 063823 (early 850) and 065074 (late, and current 850 part number)

http://www.nortonmotors.de/ANIL/Norton% ... 002&Part=1

LAB is right, of course. 06-3850 is the number for the raw casting for (originally) the 850 barrel that we now use to make 850s and 750s from.