38 Norton Colonial

1938 frame with 46 model 18 engine, but only 4 digit engine number (normally 350 designation)?
Maybe it was originally a 350 and someone "retained" the number for the 500 motor? Don't know about the Q in this scenario.

I though "Colonials" were higher ground clearance and a little less dressed for less maintained roads.

Great looking machine, a bit to go but nothing major missing, do you have the tail piece of the rear mudguard? Is it the wrong front wheel?  
 

The engine is definitely a 500cc. A3 signifies a 1946 Model 18. When production recommenced in 1946, the numbering system started with a letter (A for 1946) and a number for the model. The sequential numbers started at 1001.
Engine number A3 5255Q would have been despatched August to early September 1946.
The letter Q indicates that the cams have quietening ramps.
The frame number indicates a prewar frame from Dec 1937 to early January 1938.
The gearbox is correct for 1946 with the push-in circular disc.
A quick look at the photos show prewar girder forks with a post war front brake. By 1946 the brake was mounted on the right hand side of the girders. The forks are correct for most prewar models although several models had right hand mounted front brakes in 1937.
Handlebars are missing the tangs to mount onto the top of the forks together with the speedo bracket.
I'd also be checking the integrity of the frame repair near the rear of the gearbox.
Message me if you want any more information.

Needs a good check out.  A common failure point on open cradle frame. If it's just butt welded  I'd sleeve it or cut it out the tube and replace.

I missed out that 45-47 were also four digit numbers so as Ian says it falls in to 46.
The "3" denotes it as a model 18, I didn't realise the "Q" Quitening ramps identification started so early. I thought it a Dominator term.  Learn every day.
The mudguards we're often like this prewar,  don't know too much about Tinware changes.  Gearbox is a cleaned up version of a dolls head, commonly referred to as a tombstone.

A bit to go at but rubber wear, handlebar clamps and dynamo are generally available.  What's your intention with it?  Whatever you do I would get it into a fit state to run up and see what you have got. The ravages of time are far kinder than the ravages of some restorers, you may be lucky.

Apply for a dating cert, you have two sources of info being the frame for the bulk of the machine and then the drive train.  The records may give you some insight into its origins, and engine donor.

;-)
 

At this stage ignore the electricity. The dynamo might be a 3 brush, these were horrible things at the best of times-needs converting to two brush, modern regulator-done. This sort of machine can be completely rebuilt as far as mechanics, paint etc needs a decent magneto etc perhaps investigate purchase-even fit a dynamo. But the last thing you do/worry about is the wiring. But do locate the battery space and what is available as far as a battery.

You can't replace the wiring with the 'correct type' as it doesn't exist. NOS wiring from 1938 will be well past it usability.

The 1946 engine was of the pre-war 1938 type, although I believe that there were some small changes to the rocker box castings. To all intents and purposes, unless it's being fitted in the more compact WD16H frame, they are identical.

The horizontal rear saddle spring lugs indicate that this is not a WD frame.

In pre-war terms, apart from OHC, only the ES2 had a full cradle frame. All post-war roadster frames had a full cradle and the ES2's "Extra Specification" became plunger rear suspension.

As Richard says the ES2 had the full cradle frame, yours is open therefore Model18.  Never sure of the ES meaning Extra Sport, Extra Special, Extra Speed... Always seen as the sports version of the pushrod Nortons.
j

...will recover those mudguards. Cracks are manageable loses can be reinstated.  Far better to recover the originals, and probably cheaper.  Straight frame tubes can be replaced fairly easily tapered one also, but getting swaged tube is sometime a little difficult. Is there an issue on the lower offside gearbox tube?

Get your machine together as complete as you can then group the tasks. Motor gearbox is straightforward, they can be done in parallel to the chassis and tin wear.

Any luck with locating the original motor?
j

Easily checked by refitting inlet cam and timing cover and then checking for the amount of end float.  You can then shim to reduce the end float by fitting shims behind the cam wheel.

Hi Matthew,

   Sorry to be the bearer of bad news, but looking at your latest photos, you will not be able to use your cylinder bore as it is. The ridge around top is the actual original bore size, the lip is how much the bore has been worn away and I don't think I have seen one with this much wear before.You may get away with a plus 40 rebore, but don't be surprised if you have to go to plus 60 to get it to clean up. This must have had excessive piston slap which is probably why the rings were broken, you will need to check the rebore situation before you get a new piston.
   The head joint should not have a gasket or sealing ring and you need to grind the joints together using valve grinding paste, coarse on the outer face and fine on the spigot so this gives a very slight gap on the main contact area which will ensure the spigot seals first. Most gasket sealants can be used on both joint faces.
   

Hi Matthew,

   The wear on your barrel is unusual with excessive wear on the sides rather than the front and back. This is probably due to the 3mm end float of the crankshaft forcing the piston from side to side. The correct end float should be .005 to .010 inch with the con-rod central in the crankcase mouth. You will need to find the reason there is so much end-float on this engine as you might have the wrong main bearings or drive-side centre spacer.
   With the piston in the barrel and level at the top, you should be able slide a .006 inch feeler gauge between the bottom front (or rear) of the piston skirt and the barrel. If the gap is more than .014 inch then the bore is beyond useable tolerance, Even so, with the top wear you will need a rebore anyway. 
   Regarding the head gasket, these were only fitted to make factory production quicker. Grinding the head joint is the correct process, and to support this, no Manx or International engine had a head gasket. Make sure all the contact surface has a matt grey surface to indicate a perfect seal.

Matthew,
In your photo IMG_7136.jpeg there is a useful looking thread gauge (red), please can you tell me the maker so that I can find one.
A good supplier of piston rings is Cox & Turner and they are very knowledgable about all things that need machining in an engine, cylinder barrels and heads, see https://www.coxandturner.co.uk/
for details.  They had +0.060 rings on the shelf when I recently needed some for my Model 18.

Hi Matthew,

   The new bearings tend to be a tighter fit than the originals that were made in period and 4 thou is quite a tight fit for a steel to steel fitment and will need the con-rod to be heated. When the outer ring is fitted to the heated con-rod, the ring will probably be distorted. You will need to get this carefully honed taking off the least amount to remove any distortion or high spots.

Regarding "Colonial"...logically the WD 16H should have been either the 16C or Model 17.  'H' being originally for 'Home' as opposed to 'C' being higher ground clearance 'Colonial'.