Exhaust Valve excess gap damaged Lifter ? 74 Norton Commando

G'day all,
Today while out on a ride the left exhaust valve lifter became very noisy suddenly.
Got home took tappet cover off and discovered that the rocker arm to valve clearance was over 10 mm with no obvious fix by adjusting.
Damage has definitely happened to the valve train somewhere and Ive read posts of delamination of the contact surfaces between the lifter and cam.
Could this be the problem?. The push rod is still opening and closing the exhaust Valve but not at the correct duration.
To add the motor is smoking blowing white smoke, could this be a valve stem seal issue? Do Norton's have a valve stem seal?
The engine oil has become quite metallic as well.

Cheers
James

Jamestown said:

G'day all,

Damage has definitely happened to the valve train somewhere and Ive read posts of delamination of the contact surfaces between the lifter and cam.
Could this be the problem?.

Click to expand...

Highly likely

Jamestown said:

G'day all,
Today while out on a ride the left exhaust valve lifter became very noisy suddenly.
Got home took tappet cover off and discovered that the rocker arm to valve clearance was over 10 mm with no obvious fix by adjusting.
Damage has definitely happened to the valve train somewhere and Ive read posts of delamination of the contact surfaces between the lifter and cam.
Could this be the problem?. The push rod is still opening and closing the exhaust Valve but not at the correct duration.
To add the motor is smoking blowing white smoke, could this be a valve stem seal issue? Do Norton's have a valve stem seal?
The engine oil has become quite metallic as well.

Cheers
James

Click to expand...

Yep, sounds like you have lost the Stellite pad from the bottom of the cam follower.

No seals on exhaust valve stems only on intakes. Your issue seems like the follower pad has left the building and gone for a tour around the pushrod and cam spaces.

This is starting to look like one of those "not if but when" scenarios... are there still no viable replacements on the market?

acadian said:

This is starting to look like one of those "not if but when" scenarios... are there still no viable replacements on the market?

Click to expand...

I have purchased a few new followers from Andover that have passed the hardness test. Any follower manufactured in the past 35 years is going to be spiggoted and will not loose a pad.
Of course there were NOS non-spiggoted followers available for a long time-and there may still be some around.

But only the few poorly bonded followers are likely to loose the pad, so if your followers have considerable mileage on them, I wouldn't worry.

Jamestown said:

G'day all,
Today while out on a ride the left exhaust valve lifter became very noisy suddenly.

Click to expand...

This tells you it is a failure issue, and not really a wear issue, though certainly wear over time may well have led to the sudden failure.

Jamestown said:

Got home took tappet cover off and discovered that the rocker arm to valve clearance was over 10 mm with no obvious fix by adjusting.

Click to expand...

As has been mentioned, almost certainly a lifter pad detachment.

Jamestown said:

Ive read posts of delamination of the contact surfaces between the lifter and cam.
Could this be the problem?.

Click to expand...

Quite likely such an issue has been present for some time prior to the "failure".

Jamestown said:

To add the motor is smoking blowing white smoke, could this be a valve stem seal issue? Do Norton's have a valve stem seal?
The engine oil has become quite metallic as well.

Click to expand...

There are several possibilities for the smoke, and they could all exist to some extent, such as metal contamination to the pistons and bore, as well as to the valve guide seals, just general wear and tear (just because a lifter pad falls off does not mean everything else was/is perfect), for example.


If the oil is "quite metallic", this does raise questions regarding contamination to the rod bearings in particular, as like the pistons they can tend to be subject to impregnation of foreign material.

Total teardown. Sorry.

Are there any photos of lifters that are prone to damage by delamination floating around? I will repair the engine as no doubt it will need it.
Can anyone tell me where I can get parts in Australia? My local shop Vintage and Modern closed down a few years ago.

Thanks for the good advice I will post pictures on tear down. I did use a oil with slightly lower oil viscosity due to it being below 15 degrees here but it was Penrite Fully Synthetic. Maybe a mistake on my behalf and could of contributed to the failure?
As the bike was built long before they banned leaded petrol would the valve guides need to be replaced to suit unleaded?

Thanks

Type of petrol used has no effect on guides, it's the valve seats that can suffer from unleaded but the Norton has good valve seats.

Jamestown said:

.
Can anyone tell me where I can get parts in Australia? My local shop Vintage and Modern closed down a few years ago.

Click to expand...

http://www.roadnrace.com.au/

Classic Road & Race in Victoria are a Andover Norton parts retailer if you want stock items.
Its the only place I will buy off locally.

One piece followers are in the pipeline, the casting / material issues have now been resolved. The problem was deciding on what hardness bracket to use to suit all different types of cam in use, many materials would be hard enough but the range of that hardness was too wide.

If the tappet tip has come free, I suspect the tappet will have dropped onto the anti rotation plate which could also be damaged.