16H/ES2/19/Big 4?

Suggestion 1 is not on. The mod was the other way around. Fitting a 16H domed piston was a way to raise compression on an ES2, but the piston had to be shortened and valve pockets had to be cut. Been there, done that, on a 1953 ES2.

The most obvious thing to do would be to find a Model 19 engine and fit that. More capacity and O.H.V. You then have the advantage that you keep the original engine which can be put back if you decide to sell the bike later and want it to be original and more valuable.

I'm really not sure. You need to look up the history of the singles before and after the war and find out what changes were made in what year. I suggest you put a "Wanted" ad in Roadholder.

If possible go with a model 19 engine of the same year, or one prior to 1948 when Norton's made numerous changes to the engines. The changes seem to be mostly in the timing chest, the way cam gears operated and the cam followers were completely changed in '48.

Have you considered simply altering the gearing a bit by going to a slightly larger engine sprocket, say 1 tooth larger?

Previously wrote:

Hi Everybody,

I've recently bought a 1934 16H combination with Swallow sports sidecar which I'm really loving. (I fell for my best friends 1938 ES2 when I was 18 years old, and now 40 years on finally have my first Norton too).

However...

I'm finding the cruising speed of 40-45 mp.h with an average passenger pretty slow and would like to be able to cruise at 50 or so to reach more events etc. I've received a few suggestions and am considering 3 options. I wondered what you long-time Norton owners thought re. feasibility and power increase:

1. Fit an OHV 79mm piston to take the compression ratio up to approx. 6.5:1 to increase performance but maintain reliability.

2. Convert the engine to an OHV ES2/model 18 (I gather the bottom ends are v.similar - is it really so simple?)

3. Replace the engine with either a Big 4 or model 19 (it seems they all use the same open diamond frame...

I have a 4 speed hand change gearbox fitted.

I look forward to hearing some opinions...

Mark

Hi Mark - I believe the overall height of the OHV engines is greater but I don't know if the model 19 is higher than the ES 2/ 18-Even if the frame has no clearance issues you may have problems with the bottom of the fuel tank for your sidevalve clearing the rockerbox of the OHV engines- just a thought-Richard

As far as I'm aware, all the sv/ ohv crankcases have the same mounting points, so would physically fit in your 'Open diamond' frame. You will need though to be careful of the primary chain line as cranks and engine sprockets differred.

If you do decide to fit one of the post-'48 engines then you need to bear in mind that the magdyno drive direction was altered so this would need attention.

The Model 19 engine is appreciably taller than the 500cc unit but it will fit in any civilian frame. The same part was used for the two side-valves, the 18 and the 19. It will not though fit in the high ground-clearance WD frame which had tubes about 1" shorter (the other engines will all fit though).

AS far as I can see, for 1934 - 35 whilst the side-valves shared a fuel tank with the 18 and ES2, the Model 19 used that from the CJ and CS models so presumably had more clearance. There were various options for panel tanks and gate changes.

A couple of photos, including underneath the fuel tank would be handy as there could have been changes made over the years.