Strongest Model 16H Crankcases

The actual crankcase castings seem to have become stronger with time, but they're probably all suitable for their original purpose if in good condition.

The 1948 pattern (the "Chimney Pot engines with circular tappets) look like a stronger casting. Prior to that, the 1938 type was beefed up but these have flat lever followers which were a little fragile in the OHV engines at least. Prior to that, there was no change from 1936-'38 and WD were identical. There are probably more late WD cases around in decent condition.

Hi Robert,

   Firstly, as Richard P correctly says, the later engines have more substantial crankcase castings but these are not interchangeable with any of the earlier versions so you will need to decide which engine you want to use. After 1931 all the engines have the same mounting holes, so you can use several different types of frame with-out modification.

   Unless you are going to supercharge your engine, I think you may be over-estimating its  potential. Failures are mostly caused by abuse of these engines' low-down torque which can shear the crank-pin. The next weakness will be the con-rod which can snap if the crank-pin holds. Any of these failures will render the flywheels unuseable. Make sure you fit the correct main bearings as incorrect ones can force and break the timing crankcase bearing housing side face. The best advice is to let the engine rev freely and not let it labour.

made a very fast 16H.  I once read a web-page on it, the machine was allegedly timed at something like 118mph.  If he really got it to go that fast, well, it was faster than a long-stroke Manx.

From memory, I think he chose the 1936-8 type engine, but I'm vague on it.  The barrel was prepared with a nearly-vertical inlet tract fed by a large TT carburettor, possibly 1 3/16". The carb was low down, between the crank case and gearbox.  He fitted or made some hot cams and did various other tuning modifications.   I wish I could find the web page on the bike. No idea if it survives.

Paul

http://www.vintagenorton.com/2011/03/121-mph-model-16h-racer.html

and other advantages.... I think that the alternator bikes got a magneto or coil ignition on the three-bolt flange mount.  That being so, you can use a later magneto or magneto-replacement electronic unit. 

Or use an earlier timing cover with an oil seal where the inlet cam passes through the timing cover, and fit an ignition of your choice (contact breaker, Boyer, etc) in place of the lower ignition sprocket .  An elderly gentleman of my acquaintance did that in the '80s to his 19R

There were no alternator-equipped sidevalves so you'll be looking at extra engineering work to accept whichever top-end you choose.