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Strongest Model 16H Crankcases

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Gentlemen-

What vintage of Model 16H crankcases are the stoutest?  I would imagine the units from the WD era would qualify for obvious reasons, but I'm not certain.

Any ideas?

Thanks!

-Robert

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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.

In reply to by richard_payne

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Richard-

The short answer is because I'm going to probably blow them up, so I'd like to start with the strongest cases possible.  

As you may have inferred from some of my other forum posts, I am building a Model 1H engine to an increased specification and I'd like for things to stay together as mush as possible!

I should also add that the cases I have are original to my machine, so if I'm going to risk ruining a set of cases, I'd prefer to do it to a different set of cases.

Thanks again!

-Robert

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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.

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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

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

I have seen that article and read it with great interest.  I believe you're correct about the cases he used, but I was wondering if any of the post-war cases might be stronger due to the advances in metallurgy and engineering practices during the war.  

I have been corresponding with Mike Pemberton, and his thought is that that one of the later alternator-equipped bocks might be stronger.  Any thoughts?

For now, I've been looking for cases from different eras for evaluations.  If anyone has a matched set of cases they'd like to sell, please let me know.  If the price is reasonable, I'd be interested.

Thanks!

-Robert

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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

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

 


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