Manx Norton 40m Restoration (I hope)

A little frenzied activity over the last week or so.

The summer has been a nightmare, everything being turned around far too slowly. Parts delivery has been appalling with 2 weeks waiting time tuning into 4 weeks then 8 weeks then 16weeks, some specialist services have been very problematic which pushed my blood pressure well into the danger zone i.e. Waving a 1 meter length of scaffolding pole and shouting threats of execution did speeded things up a bit though. But just like waiting hours for a bus to turn up then many turn up all at once, so it was with the parts I had been waiting months for, everything turned up at the same time but for 3 different bikes!

So over the last few weeks I've got stuck in and have pretty much finished the rolling chassis, just a few parts to fit but these are bolt on and therefore no great drama. That said there are few bits with a chrome plater who I am sure makes his tea using the liquid in his plating baths. He's totally barking mad.

Anyway the front end is now on and oiled up. Everything has been stripped and cleaned, measured and found be generally OK with just a little wear on the stanchions. I have made new upper fork shrouds in alloy, as used by John in period, I think the originals came from Norton and are similar to those used by works bikes 1951 - 53. Note the correct type mudguard bracket for Manx up to 1956 (Y brackets turned up in 57.).

Lower fork legs were in good condition, so linished then polished. New seal holders as the old ones were battered, sometimes its just not cost effective to restore and re-chrome. Made new alloy brake air scoops, larger top scoop is works type, lower rear is standard but its hard to see. The brake linkages are a mix of original and new replica using whatever I could. Internally the brake condition was remarkably good so a quick assembly and adjustment after the clean up.

Fork crown area turned out nice and bang on period wise.

Rear end had problems like the sprocket studs and dowels were wrecked so been reinstated at mid point.

All repaired and fitted. Rear shocks are the originals refurbished and have made new alloy top and bottom shock shrouds again a used on early works bikes and by Surtees.

The chassis needed everything, it was bent, brackets cut off, brackets added, the rear subframe and upper shock mounts were mostly scrap. The frame restored back to standard / original!

The chassis just about finished!

Next is engine assembly time!

Best would be something that feels nice in your hand, something you're used to holding onto.....

doogalman said:

Wow, really coming on nice. Out of curiosity what handlebar grips would be correct for out of factory finish?

Click to expand...

Amal used to supply their own grips and were fitted to Norton originally but some hated them because their grip would hold oil which would be flying everywhere on an open valve spring manx at 7200rpm. So some used ribbed type like Doherty. The ribbed Amal type turned up later in the 60's. But many used whatever they liked from radiator hose to linen adhesive tapes. I have fitted modern medium compound Renthal in black which are the best on the market in my opinion and they don't degrade with UV light exposure or with oil or fuel. Both of those picture below will last a few years then fall apart.

Amal

Doherty

2017 was a busy year a unfortunately several race bikes with troublesome engines distracted me a bit. But finally, yes finally I am back on this Manx.

The magneto was a mess - When patina is a pain in the butt.

When I 1st removed this Lucas 2MTT magneto from a Manx engine I thought it was likely scrap resulting from years and years of neglect and to be truthful I didn't want to get involved with it. And knowing that the 2MTT magneto was incorrect for a 1955 Manx I spent about a year trying to find the correct item, a Lucas SRR but I had no luck. So I rolled my sleeves up expecting trouble.....

The attached photos show exactly how bad the magneto was when stripped, through preservation to rebuilt and pressure tested. The worst parts being the drive end bearing holder which was scrap and magneto top cover which after light blasting almost fell apart but I managed to salvage 90% of the rest including the coil. I was very lucky to find some new old stock Lucas parts and I remade others.
All the fasteners are original which i might re-black to sharpen it up a little, the Lucas ID plate is the original which will stay complete with a few dents and faded paint. I think it turned out OK in the end.

The pictures say it all!

Onto the engine.....

1st a few before photos!

You name it its been sorted. Crank has been stripped and light blasted and treated. New rollers in the big end and new small end, then assembled and trued. Crankcases were a mess but have been light blasted and chromated. The main bearings are the originals which despite looking horrible were good, just one roller in one race was knackered but guessing this was breaking up in use rather than due to corrosion. You might think i could just buy another = wrong. These bearing races made by Hoffmann haven't been available for years so the only solution was to remove the cage rivets open the bearing, replace the damaged roller with a graded item (slightly undersize) then reassemble and rivet the cage up.

Restored main refitted.

Rebuilt crank installed and shimmed against the timing side main to ensure the crank is central.

Crankcases back together with oil pump fitted.

Still waiting for a piston to turn up!!!!

Work the heads - Two heads photographed, in the foreground in the original head for this bike, compare to the later head? Note the shallower squish shoulder on the early head (1954 to 1956). The later head use a higher crown piston, either three or two ring type. Both inlet and exhaust ports have been reworked opening the throat of the valve seat which reduces the valve seat area, also the ports have been polished through and are a work of art. Not my work i must say, this engine have been through the hands of Norton works shop, Francis Beart and Jim Smith (Jim prepared engines for Phil Read, Joe Dunphy amongst others).

The cylinder - The cylinder has been relined and bored to size but the spigot have not been notched for connecting rod clearance, so over to my draw full of metal files, a few lumps of plastiguage and fit the ring-less piston to the rod. Mark the bore approximately and then get filling, trial fit, remove, file, trial fit, remove file until close. Then plastiguage, measure clearance, file and so forth. Clearance of around 0.045 to 0.060 thou

Lower bevel clearance (same applied to top bevels) - There are always tight spots on the bevels, sometimes very obvious sometime not so BUT always shim to the tight spot. Remember the greater clearance you allow the more backlash in the timing and the greater shock you with put on the valve train (throttle on to throttle off). The manx engine is alloy it will grow with heat so bevel clearances should be close perhaps just a few thousandths of an inch set with bronze and thin steel shims. Remember measure clearances with all holding bolts fully tightened and make allowance for gaskets cement. In period they were built without any and just two gaskets.

Modifying the piston - The cylinder is the short type fitted from 1961 to 1962 and uses a two ring piston. Now go to the top photo of this post and look at the heads again, see the different squish shoulder, yep that means i have to machine the late piston for the early head. Piston altered below. Its not just a simple case of putting in a lathe though and spin it up. The squish measurement is vital and needs to be around 0.040 to 0.045thou. So its bit by bit and little like fitting the cylinder, i fitted a 0.040 thou compression plate under the cylinder and work away from there, machining the piston close, trial fit, plastiguage, measure and adjust. This allows me a little margin for error or rather i can alter the base plate thickness to get the squish perfect.

Modified Piston below.

Cambox - Whats to say, I could write a 50 page dissertation. They are not that complex they just need to assembled with care. All bearings fitted square, and end floats corrected. The cam shafts by the way are Vernier pegged and can be taken apart for accurate valve timing.

Does anyone know how to remove the big image below?

Cam timing - Timing a Manx isn't so complex, but it does need patience.

Before any attempt to time the valves, piston squish (see previous post) , top and bottom bevels running clearances must be set and valve drops at TDC - Always make sure the valve fully falls into the valve pocket on the piston, often they do not and catch the pocket edge, most often on the inlet valve. A little micrometer blue on the valve and spin whilst in contact with the piston to check.

Also you need some specialist tools in addition to a degree disc and pointer. What exactly is needed depends on the method of timing - either timed with running clearance or timed with 0.040thou of lift and no clearance. I prefer to time with running clearances.

Late 350 figure below (you can go a few degrees either way).

Valve Drop at TDC not less than -
Inlet 0.330”
Exhaust 0.245”

Squish at TDC .040 - 0.045”

Valve Timing.
With 0.008” Tappet clearance
Inlet Valve Opens 71 deg btdc
Inlet Valve Closes 93 deg abdc

With 0.017” Tappet clearance
Exhaust Valve Opens 74 deg bbdc
Exhaust Valve Closes 59 deg abdc

Late 350 inlet and exhaust cams.

Obviously start at TDC. You have 3 Vernier adjustments 1/ Top input bevel, 2 and 3 at the cam shafts.

Engine back in.

Clutch and primary sorted, breathers fitted, oil tank fitted too.

Note the period primary chain oiler!

Latest bike coming together, a 3 cylinder Yamaha in full monocoque chassis!