Camshaft lobe indentions

After splitting the cases and having a closer look at the lobes on my camshaft there seem to be small intentions on the crown of two of the lobes.
The cam is marked with AN so it must come from Andover Norton but unfortunately I cannot say how long it has been in there.
Is it possible to rework the surface with a sharpening stone like the ones used to sharpen knives or could a fine grade of emery paper supplement?
I measured the lobe dimensions and there is negligible wear, the same with the bushes and bearing surfaces but the tappet blocks have survived undamaged. There is slight scoring on these surfaces but not from blast grit more like fine dirt as this engine was run without a filter installation.

You can’t polish that out.

Use it as a core to get the lobes built up with stelite perhaps ?

Even though its out of warranty ask for AN's advice anyway, it looks like a chilled cast iron cam so you need to ask them if it can be repair welded anyway.

As Eddie says, at best only fit for a core, and being chilled cast, which it does look like, personally I would just acquire a replacement.....

I binned a hard weld cam for less!

Make a lamp out of it and you can rely on a lifetime of perfect service. Seeing the difficulty to get to if a repair is effected and goes south..... I wouldn't chance a repair.

Oh man Oh man!
I couldn't help but to believe what you have just said, but then someone might have had a marvel up his sleeve.
I will speak to Joe Seifert and see what he says when he comes back from holiday, mean while on to the order list it goes.
Thanks for the input

I had a similar experience, but caught the defect(s) when I opened the box. Sent it back to AN and they replaced it. Do check the tappets.

Best.

Just checking…..when you installed the AN camshaft did you regrind the lifters. I was told this has to be done or you will get the wear you are showing on the cam lobes.

Norton camshafts can be a bit delicate if not treated well.

Firstly if possible preserve as much of the crankcase oil bath as you can. Many have been ground away with the use of higher lifts

Then get a well made cam from a reputable dealer. I measure and check every new cam off the pushrod with a dial gauge and degree wheel and there are some poorly made ones out there. Common issues are poorly machined quietening ramps and different lobe centres. This also give you the data to degree in your cam if you want to go that far. Remember the lift value you measure of the push rod is not the published lift because you are not including rocker ratio. This is a quality check mostly.

Either reface the followers or instal new ones.

Use cam lube for assemble. This is usually supplied with the new cam

As part of the dial gauge cam accuracy check you can also check the lifters are moving freely over the full lift range. Sometimes they can hang up.

Then make sure you don't have coil bind on the valve springs. Some people recommend at least 100 thou clearance. I have used down to about 60 on a race bike. Obviously also clay the pistons and check nothing is touching there which could overload the valve train.

Check your push rods are not binding in the tunnel or on the head gasket.

Pour an egg cup full of oil down the pushrod tunnels immediately before start up. I also do this if the bike hasn't run in a month.

DO NOT let the bike idle on start up until you have checked full oil return and its warmed up. I use about 2000 rpm minimum

Letting a cold bike idle is a cam killer. Plus you should really tune a Norton to idle around 1000 rpm minimum. Very low idle kills cams.

johnm said:

Norton camshafts can be a bit delicate if not treated well.

Firstly if possible preserve as much of the crankcase oil bath as you can. Many have been ground away with the use of higher lifts

Then get a well made cam from a reputable dealer. I measure and check every new cam off the pushrod with a dial gauge and degree wheel and there are some poorly made ones out there. Common issues are poorly machined quietening ramps and different lobe centres. This also give you the data to degree in your cam if you want to go that far. Remember the lift value you measure of the push rod is not the published lift because you are not including rocker ratio. This is a quality check mostly.

Either reface the followers or instal new ones.

Use cam lube for assemble. This is usually supplied with the new cam

As part of the dial gauge cam accuracy check you can also check the lifters are moving freely over the full lift range. Sometimes they can hang up.

Then make sure you don't have coil bind on the valve springs. Some people recommend at least 100 thou clearance. I have used down to about 60 on a race bike. Obviously also clay the pistons and check nothing is touching there which could overload the valve train.

Check your push rods are not binding in the tunnel or on the head gasket.

Pour an egg cup full of oil down the pushrod tunnels immediately before start up. I also do this if the bike hasn't run in a month.

DO NOT let the bike idle on start up until you have checked full oil return and its warmed up. I use about 2000 rpm minimum

Letting a cold bike idle is a cam killer. Plus you should really tune a Norton to idle around 1000 rpm minimum. Very low idle kills cams.

Click to expand...

The lift of the pushrods I could measure on rebuild but what sort of measurements would I be looking for or should both have the same lift co-ordinating with the degrees of lift.
I can but only install an AN cam as I am not familiar with any better but I will scrutinise it be assembly. The followers had perfect faces on them which led me not to understand the cam damage. Despite I could as a measure get them reached but how much hardened material can one play with there?
Coil bind I have read about but not fully understood, at a guess the inner valve coil either expands or bows causing fouling of the outer coil but controlling this I take it that the 0.100 thou should be the cold play between coils.
Pushrod bind had been apparent on strip and the other points have always been observed.

Many thanks
John

Woody850 said:

The lift of the pushrods I could measure on rebuild but what sort of measurements would I be looking for or should both have the same lift co-ordinating with the degrees of lift.
I can but only install an AN cam as I am not familiar with any better but I will scrutinise it be assembly. The followers had perfect faces on them which led me not to understand the cam damage. Despite I could as a measure get them reached but how much hardened material can one play with there?
Coil bind I have read about but not fully understood, at a guess the inner valve coil either expands or bows causing fouling of the outer coil but controlling this I take it that the 0.100 thou should be the cold play between coils.
Pushrod bind had been apparent on strip and the other points have always been observed.

Many thanks
John

Click to expand...

OK. A few things.

The cam followers can be dressed by a engineering shop. They should only take off a few thou and there should be plenty of thickness available on the stelite pads. Check the pads for cracking and any sign of oil staining at the pad follower interface which might indicate they are detaching.

Coil bind is if the valve is opened so far by a high lift cam that the valve spring can no longer compress. Usually only an issue with race cams. Check it by setting the valve at full lift and then levering down the valve further until the spring binds. Put a dial gauge on the valve collar while you doing this and check how far the valve moves before it binds.

It is nothing to do with the inner and outer spring touching. Just simply compressing the spring and checking it doesn't bind before the valve is fully open. Aim for at least 100 thou on a street bike. You should be fine with a street cam.

Measuring the cam is not so much about measuring the lift but checking the quietening ramps are properly machined. And the lobe centres are the same of both pairs of lobes. Ie are thee inlet lobes the same on left and right sides. Look at the cam profiles on Dyno Dave's site.

Also check the rocker above the pushrod cup on the inlets, I have had a case of rocker engaging with underside of head in that area.
Tappets can be refaced, the tip material is Delchrome C, not stellite if the grinder asks. The one piece tappets are a castable Cobalt Chrome alloy it can be ground but may need a decent wheel to do it.

Woody850 said:

The lift of the pushrods I could measure on rebuild but what sort of measurements would I be looking for or should both have the same lift co-ordinating with the degrees of lift.
I can but only install an AN cam as I am not familiar with any better but I will scrutinise it be assembly. The followers had perfect faces on them which led me not to understand the cam damage. Despite I could as a measure get them reached but how much hardened material can one play with there?
Coil bind I have read about but not fully understood, at a guess the inner valve coil either expands or bows causing fouling of the outer coil but controlling this I take it that the 0.100 thou should be the cold play between coils.
Pushrod bind had been apparent on strip and the other points have always been observed.

Many thanks
John

Click to expand...

Coil bound....

Take a valve spring and put it in your bench vice, across the jaws.

Now compress the valve spring until the individual coil windings begin to touch each other. When they are all touching the spring is solid, and known as coil bound.

Begin to open the vice, when gaps appear, measure them. The minimum gap should be say, 0.100", thou people have used .

Now measure the length of the spring. What you are trying to achieve is to get the spring compressed to this length when the cam follower is on the nose of the cam.

Spring efficiency can be better when approaching this compressed length. Shimming under the valve seat helps to achieve the desired length.

Years ago, we didn't have readily available gauges to measure spring pressure. So these figures were used to confirm your valve spring set up.

(I bought W&S valve springs from Mick Hemmings, and I am sure he told me set them 0.050" from coil bound!! But we are talking 45 years ago!)

With a gauge, you can choose the spring seat pressures you want when the valve is fully closed. For this you measure the distance between the seat and retainer to determine installed length.

Measure the length of the spring at the required pressure. Your aim is to install the spring at this length and shim under the spring seat to achieve that seat pressure, rather than towards coil binding.

Then, after installing the head, you must check that the valve springs do not become coil bound at full lift, by measuring the gaps between coils when fully compressed.

But this is race engine set up!

'Mild cam' with standard springs (and Remember Norman White advises standard springs even with a PW3), you just need to check that nothing is binding.

Madnorton said:

Also check the rocker above the pushrod cup on the inlets, I have had a case of rocker engaging with underside of head in that area.
Tappets can be refaced, the tip material is Delchrome C, not stellite if the grinder asks. The one piece tappets are a castable Cobalt Chrome alloy it can be ground but may need a decent wheel to do it.

Click to expand...

I know this has happened on some Fullauto heads where the casting is thick, pretty sure it is reported here on a thread somewhere, maybe 5 years ago or more. (Not saying it hasn't happened to a Norton head).

I ground some metal away on mine to make sure, but I think this was just a caution in the end.