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600cc crankcase query

Submitted by graham_bingham on Thu, 25/01/2024
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Singles

I have a '57 600cc single engine in a '48 ES2. I've currently got the engine apart to sort a crankshaft end float problem. There is something about the timing side crankcase and cover that I don't understand and would appreciate some help please.

Photo 1

When I removed the timing cover the top recessed hole in the magneto drive area of the cover didn't have a bolt in it

Photos 2 and 3

The hole that didn't have a bolt in it lines up with a small oilway from above in the crankcase face instead of a threaded hole. The larger hole in the crankcase face above and to the left of the small oil way looks like it has had a stud break off in it and someone has tried to drill it out, this larger hole mates up with a small oilway in the timing cover which comes up from the pressure release valve. When I took the engine apart there was a gasket fitted which covered the larger hole on the top left effectively blocking the oilway from the pressure relief valve. 

I had a problem with the bike leaking copious oil from the magneto drive housing, could this be due to the issues above? Do I have an incorrect timing cover?

The oilway in the crank case coming from above, lining up with the unoccupied hole in the magneto drive housing allowing oil to flow into the housing? and what about the oilway coming from the pressure release valve effectively being blocked off by a gasket. Even if I didn't put a gasket back the oilway from the pressure relief valve would only connect with the large blanked off hole with what looks like a broken stud in the bottom of it.

Any thoughts from those that know would be greatly appreciated

Many thanks 

Graham

 

 

Attachments
Photo 1.jpg
Photo 2.jpg
Photo 3.jpg

Submitted by richard_cornish on Thu, 25/01/2024

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Hi Graham,

   I have seen crankcases and their timing covers that have had different locating hole positions to what would be regarded as normal. These, I believe, were from around the late 1940s and the castings all had the letter Q stamped on them. The Norton factory said that these were engines with different cams with extended ramp profiles for quieter mechanical noise, hence the Q. My own opinion is that there was a machining mistake and they wanted to use the incorrect parts rather than scrap them. Check your timing cover to see if it has a Q stamped on it.

   Your best bet will be to trawl the jumbles or advertise to get another timing case, but don't buy anything with-out trying it on your crankcase. By the way, the oilways feed the back of the cylinder barrel for the piston skirt.

Thank you Richard

Does that mean that the oilway in the timing cover coming up from the pressure release valve should mate up with the one in the top left of the timing side crankcase?

Submitted by richard_cornish on Sat, 27/01/2024

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Hi  Graham,

   Yes that's correct, the hole then exits at the top of the crankcase rear into a corresponding hole in the cylinder barrel. Did you find any sign of the Q marking on the cover ?

Hi Richard

No sign of any Q marking on the cover and when I poked a bit of wire up the oilway it came to a blocked end. Looking at the crankcase/barrel mounting face towards the rear there is what looks like an oilway but again it is blank (it is only about 2mm deep)... the plot thickens.. photo attached I checked the barrel and it does have a corresponding small oilway in the base which exits about 1/2" up the bore

Graham

Attachments
oilway in crankcase.jpg

Submitted by richard_cornish on Sat, 27/01/2024

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Hi Graham,

   These holes are bored in from either end so try squirting oil down from the top to check the oilways are open. The sharp angle of the drillings can appear like a dead end.

Submitted by graham_bingham on Mon, 29/01/2024

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Hi Richard.

I managed to clear all the oilways and have now squirted oil from the top of the crankcase and had it running out of the hole in the timing cover mounting face. I also cleaned out the drillings in the base of the barrel which were blocked with silicone gasket sealer.

The major issue is that the oilways in my timing case and the crankcase half do not match up.

I struck lucky yesterday and found out that a friend of a friend is currently restoring a Model 19S engine. I took my crankcase and timing cover round to his workshop to compare. When viewing the timing cases from the rear there is an obvious difference. Mine has the oilway above the top mounting bolt hole and his has the oilway below, see photo's.

So I'm now on the hunt for the correct timing cover so that I can reinstate the oil feed to the rear of the cylinder.

Any idea what engine the timing case I have is off? 

Thanks for your help

Graham

Attachments
Incorrect timing case.jpg
Correct timing case.jpg

Submitted by bruce_lindsay1 on Tue, 30/01/2024

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…I removed the timing case from a ‘parts only’ 1950 (E prefix) ES2 bottom end that’s lying in the shed and the oil drillings are matching the incorrect timing case you have. I’m no expert so this is a guess, but you mentioned your motor is a 57 which from memory is into the alloy head era… so my guess is the cases went through an update, maybe when they moved from the iron head to the alloy head motors, and that it might be worth homing in on the later variants to get the part you require.

cheers, Bruce

Submitted by don_anson on Tue, 30/01/2024

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Graeme, 

I wouldn't be to enthusiastic about unblocking the oilway to the back of the cylinder. 

My ES2 was a chronic plug fouller until I blocked it off.

Hi Don,

That's an interesting thought, although I believe that the flow is somehow adjustable with the screw low down on the crankcase. Did you try adjustment before blocking off?

Graham

...but I remember reading in E M Franks book that

"The only point of adjustment in the lubrication system is the adjustable feed to the cylinder wall situated to the rear of the tell-tale" Sometimes "not adjustable but permanently set and plugged with a ball and grub screw, Where adjustment is provided this is approximately correctly set when the adjuster is one turn back from the fully home position, but if the engine shows a tendency to smoke continuously the supply should be reduced"

Later in the book in the section about rebuilding the engine it says

"Cylinder oil-feed adjuster...This should be set one half to three quarter turns back from the fully home position and subsequently adjusted till there is a slight blue haze from the exhaust when the throttle is opened rapidly"

Is this adjuster not the screw slot in the lower crankcase just below where the oil pipes enter the engine?

Graham

Submitted by michael_rettie on Thu, 01/02/2024

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.....is a problem with rings/bore or valve guides. Messing with oil feed probably the wrong tree to be barking at.  Heed the voice of experience.

Submitted by richard_cornish on Fri, 02/02/2024

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Hi Graham,

   The pushrod OHV engines changed over the years. When the engine was re-designed for 1938 the oil tell-tale was omitted and this was also the case with the 1948 re-design. The quotes from the Franks manual relate to the OHC engines which remained unchanged over their production life. The screw you mention on your engine is only a blanking screw with nothing behind it. During the 1950s the quality of the piston material improved and lubrication was not so critical as before.

   If you did want to reduce the amount, you could put a restrictor in the crankcase oil-way behind the timing cover, but as Michael says if the engine smokes that much it's probably wear issues.

Submitted by john_doig on Fri, 02/02/2024

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It might be worthwhile checking the breather valve - when these wear out the engine will smoke and blow oil out everywhere, as well as oiling plugs.

John

 

 


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