leaking oil from cylinderhead Norton Model 50 n13 1958

Dear All,

On behalf of a friend of mine I have some questions. His Norton leaks oil from the cilinderhead.

What is the best cylinderheadgasket to use in this case?

What are the torqs to set for the cylinderhead?

(he has an old workshop manual wich states the torqs in degrees and perhaps because of that he tightened it up too strong. He also says that he does not dare to tighten it up too strong again otherwise the pushrod busses/tubes will tear/maybe the pushrod bus/tube distance is not accurate anymore because of leveling the cylinderhead after distortion in the mating surfaces.)

ive read on the nortonownersclub uk that leakage is also possible via the crushwashers on the stud's I was wondering if this is also the case for this model(model50 n13)?

Many thanks in advance,
Kind regards,
Jakko Vleugel
Arnhem the Netherlands

JC, has he explored where it is leaking oil from ?
And, what sort of head gasket was he previously using ?

Does his head look at all like this - with the 2 oil drains front and back ?
This is an earlier head, but later was similar (?).
https://s22.postimg.org/3kwnzyzpd/M50cylhead.jpg
(pardon the rust)

I've seen folks say they use no head gasket.
But, how can this possibly seal the oil drains off from leaking ??

The supplied head gasket was a thin aluminium affair
- and importantly, it had provision for sealing those 2 oil drain holes.
(just by having 2 holes in the gasket).

The stud holes and washers etc should be totally isolated from the oil,
so should play no part in oil leakage.

Jakko,
the extract below is a cut and paste from, the now sadly departed, George Cohen's web site. If you are using a gasket then the same principles will apply.

Regarding the oil drain holes - some people machine a recess around the hole in the top of the barrel to allow an o ring to be fitted. The o ring obviously needs to sit proud and then be compressed by the head. My ES2 had this done prior to my ownership, it seems effective.

23. CYLINDER HEAD JOINT
An all the single cylinder engines I have worked on (from an all iron head & barrel twenties OHV to an all alloy sixties DOHC Manx) the same principals and engineering apply.
There is NEVER a gasket. The idea is known as the “double ground joint”.
The theory is simple, the engineering a little more difficult.
The head joint comprises of two parts; the spigot interface and the wider head barrel joint. Say, the spigot on the barrel is 0.125 inch high, then the recess in the cylinder head needs to be 0.124 inch. This means that the seal is at the spigot joint and the wider joint is to prevent distortion.
The practically, especially on well used alloy top ends is a tad more difficult. If you measure the spigot height on the barrel, it is unlikely to be the same all 360 degrees around. The same applies to the wide surface on the barrel. With frequent and less frequent heating and cooling over 50 years the original manufacturing tolerances have been lost and distortion has taken place. On a fifties Manx engine I worked on last year the barrel, at the wide flat surface was distorted by 0.008 inch and at the spigot, 0.005 inch. The cylinder head was worse, with the wide surface being 0.013inch off flat!
Consequently these defects need to be corrected.
Mounting the barrel in the lathe and truing up and machining is relatively easy, but the cylinder head is more difficult. A special jig has to be made up to allow the truing up to be established. A good medium size lathe, grip true facility, magnetic face plate and some clever thinking is required.
The goal is to obtain a double joint with the spigot of the barrel mating in its recess . For Iron head and barrels, there is rarely any distortion and the easiest way to obtain a good joint is as follows: Hold the cylinder head upside down in the vice (securely but without causing any damage). Put some coarse grinding paste on the broad surface and fine in the spigot recess and add a few drops of thin oil to both. Carefully fit the barrel onto the head and with a anti-clockwise and then clockwise rotating motion, lap the two together. After a few minutes, wash of all the paste and oil and inspect. You should be able to see the lapping on all surfaces. Repeat until a perfect face on both broad surfaces and spigot are established.
Torque Iron set ups to 45 ft/lb and aluminium one to 32 ft/lb. You can use a very slight smear of either a hard setting goop or even a smear of oil or grease, which will burn hard.
Hey Presto, no more oil leaks.

ntst8 said:

There is NEVER a gasket. The idea is known as the “double ground joint”.

Click to expand...

Thats interesting.
The parts book for my ES2 says there is a head gasket, and one came with it.
This enabled the factory to just bolt them together, and be oil tight (?).

Without that mod for the o-rings, getting an oil tight joint in a double ground joint could be rather tricky. (?)

And, if the spigot has been ground down flat and ground down flat and ground down flat, then what do you do ??
Apart from a LOT of grinding !!

Cheers !

To Rohan and Ntst8,

Thanks A lot for the quick responses!

In your post's I see very usefull info at first glance...

however i'am not native(technical) english so i use google translate to proces the info.
this takes some time.

I will come back asap with pic's of the cylinderhead(to show where the leakage occurs), cylinder and gasket.

Kind regards,

Jakko Vleugel

Hi Rohan,

you are right, i should have commented on that.
My ES2 had the standard thin aluminium head gasket when i bought it, but the o ring mod had already been done. Mine also had a hand cut shim above the spigot - an alloy barrel which had been resleeved with incorrect spigot height!! The shim was thinner than the head gasket so i had a local engine shop convert it to shim and gasket free.

cheers
iain

Rohan said:

ntst8 said:

There is NEVER a gasket. The idea is known as the “double ground joint”.

Click to expand...

Thats interesting.
The parts book for my ES2 says there is a head gasket, and one came with it.
This enabled the factory to just bolt them together, and be oil tight (?).

Without that mod for the o-rings, getting an oil tight joint in a double ground joint could be rather tricky. (?)

And, if the spigot has been ground down flat and ground down flat and ground down flat, then what do you do ??
Apart from a LOT of grinding !!

Cheers !

Click to expand...

To Rohan,

Norton Model 50 N13
https://postimg.org/image/v0sdazy19/
Now the Cylinder head looks like aluminium to me about the cylinder I'am in doubt between iron and Aluminium.(because the Cylinder is painted black on the Norton model50 pic)
Hopefully you can tell what is what

Cylinderhead(black cross marks approx the leakage place)
https://postimg.org/image/vnra0iux9/
(pardon the coal residu)
Quoting Rohan: Does his head look at all like this - with the 2 oil drains front and back ?
This is an earlier head, but later was similar (?).
https://s22.postimg.org/3kwnzyzpd/M50cylhead.jpg
(pardon the rust)
This earlier head looks indeed pretty simular

Cylinder(black cross marks approx the leakage place)
https://postimg.org/image/cjxyk6i31/

Gasket(at the leakage side it looks a bit distorted to me)
https://postimg.org/image/4v148ghl9/

my friend say's it is a metal gasket

Qouting Rohan:
Thats interesting.
The parts book for my ES2 says there is a head gasket, and one came(a filler?) with it.
This enabled the factory to just bolt them together, and be oil tight (?).

Now my friend is saying that the head is flattened in the past but and now it does not look completely flat. We where talking about thicker or double headgasket's also to cover up the change in overall distance/length because of the flattening of the cylinderhead. He Told me that he already head a teared push-rod tube/bus when tightening (perhaps too strong because of the vague degrees stated for tork in the old workshopmanual)the cylinderhead. Wich means that the overall lenght in comparison with the lenght of the push rod tube/bus is perhaps not accurate anymore. And when the head is flattened the the recess depht for the spigot is not accurate anymore. So somehow we have to figure this out. Measuring the spigot height and recess depth.(that is the trouble with over 50 year old machines it is difficult to tell what is happened to it without service history/documentation/logbook)

So What You are saying Rohan Could just do the trick: a gasket and a (filler)gasket.(if we are lucky)

Also I found on Nortonownersclub Uk in case of disortion in Cylinderhead/cylinder they talk about a copper gasket in combination with a copperfinedustcompound. I think because it is softermaterial and set's itself to the distorion form.

Thanks A lot for the usefull info sofar.
Cheers,
Jakko

To Iain,

Norton Model 50 N13
https://postimg.org/image/v0sdazy19/
Now the Cylinder head looks like aluminium to me about the cylinder I'am in doubt between iron and Aluminium.(because the Cylinder is painted black on the Norton model50 pic)
Hopefully you can tell what is what

Quoting Ntst8;
the spigot on the barrel is 0.125 inch high, then the recess in the cylinder head needs to be 0.124 inch. This means that the seal is at the spigot joint and the wider joint is to prevent distortion.The practically, especially on well used alloy top ends is a tad more difficult. If you measure the spigot height on the barrel, it is unlikely to be the same all 360 degrees around. The same applies to the wide surface on the barrel. With frequent and less frequent heating and cooling over 50 years the original manufacturing tolerances have been lost and distortion has taken place
(it could be very well be the case that the spigot height and the recess depht is not accurate any more 360 degrees around because of distortion and flattening of the Cylinderhead. we have to measure that and if wrong height and depth we have to take action consequently)

Torque Iron set ups to 45 ft/lb and aluminium one to 32 ft/lb(thanks for the Torq's)

Thanks A lot(also to mr. Cohen) for the usefull info sofar.
Cheers,
Jakko

I should have commented at the time.
That cyl head I posted a pic of for the oil drains is alloy, with an iron skull.
Think its circa 1955 ish.
Sits on an iron cyl, as nearly all Nortons had.
(except alloy cyls on Inters and 500T and compy motors to special order)

I've a couple of earlier Nortons, and they are all iron top ends - iron head and iron cyl.
The alloy heads seem to want to warp a bit, which may be why they may get difficult to seal later in life ?

A trick I've used is to lightly spray the gasket surface and/or the gasket with aluminium paint.
Let dry, and then assemble.
This seems to lightly glue the parts together, and seal well.
Without being difficult to take apart later.
Obviously, it won't work for large gaps (!)
hth

@Rohan

Thank's a lot for the info.

cheers,

Jakko