Valve Train Wear

[swooshdave]

So I got the spindles out. Video in the other thread.

I pulled the rockers and associated stuff out to inspect (and clean). Not sure what I think of these parts.

Right Exhaust. The valve cap wouldn't come off (I didn't try very hard). The Left Exhaust Cap cap off easily. Is this acceptable wear?

Left Exhaust. Time to replace?

Intake Valves. There isn't a cap on these? Also one side the rocker didn't have a shim. Only one shim and the spring. I looked everywhere for the shim. Could not find. Is that unusual?

 

[Fast Eddie]

Is the wear acceptable? Depends how many miles it’s done swoosh. Is it acceptable as in are the parts re usable? No.

Don’t forget your engine ran without oil pressure... the head only gets a dribble anyway, yours will therefore have ran for a while with none, so things are gonna look bad.

Whatever the cause was, you either need new valves or reface the tips, and new adjusters.

Shim could have been left out deliberately to get good alignment perhaps?

 

[Onder]

One reason I use caps is to spare the head of the valve stem. Easy to toss and replace. The tappet pin likewise. All my british bikes or at least the
makes I've owned seem to have fairly short lives in the valve department. I'm sure yours would still do a lot more miles but Austerity is over, no need.

 

[Hortons Norton]

Only the exhaust valves had the lash caps? Seems odd.

 

[batrider]

Those look pretty good. It doesn't take long for them to get a real dished crater though if the bike gets ridden.

 

[baz]

There can be a lot of variables on an old engine , especially a Norton one
Plus if it's a combat the head has been shaved
Plus there maybe valve seat recession
It'll be best to check the valve geometry with a dry build and adjust push rod length and valve springs for coil bind etc
I have never used lash caps on a norton but I can remember on a BSA I had the shoulder of the lash cap was touching the collets
So I had to grind the lash caps back a little incase the collets came loose

 

[acotrel]

When I set tappet clearances, I don't use feeler gauges. The thread on the tappet is usually 26 TPI and there are 25.4 mm in an inch. So one complete turn of the tappet is 40 thou of an inch. A quarter turn of the tappet from fully tight, is ten thou of an inch (one flat on a square headed adjuster ) - and an eighth turn is two thou of an inch ( half a flat). That way it does not matter if the valve tip is dimpled. But the wear pattern you have is more than normal dimpling. Hold the tappet, while you tighten the nut.

 

[swooshdave]

Are valve caps suppose to be on all valves? Or do I recall something about not using them on Combats?

 

[Fast Eddie]

Are valve caps suppose to be on all valves? Or do I recall something about not using them on Combats?

I didn’t think valve caps were standard fitment on any Commando were they?

Combats had .040” shaved off of the head swoosh and did not have the pushrods similarly shortened. The net result of this being less space between rocker arm end and valve tip. That’s probably why you heard about not using them on Combats.

 

[swooshdave]

And yet here we are.Valve caps on the exhaust.

 

[Fast Eddie]

My guess is someone wanted to fit them on all valves but there was no space on the inlets so they left ‘em out.

As has already been suggested, you’ll need to look at all of this when you re-assemble. Then you can check the rocker striking angles and decide what to do.

 

[baz]

As Eddie says you have to get the rockers striking the valves correctly or it will wear the guides and valves out very quickly
Also I always do away with the thackery washers and shim the rockers to the centre of the valves but there are various opinions on this
I would dry build that motor and get the push rod length correct
Because somebody has fitted lash caps somewhere along the line

 

[acotrel]

I have not bothered to even lighten the valve gear in my motor, because it is never revved high enough to need it, and the cam is not severe. When I had a pushrod motor that use to rev to 10,500 RPM, I used to cut the tappet lock-nuts in half and use Wassell tappets which were hollow and adjusted by Allen key. I would never use valve caps, if I could avoid it .

 

[lcrken]

I've used lash caps on Commando big valve heads to correct for the shorter length of some of the valves (Gold Star intakes, etc.), and once to provide an acceptable wear surface for titanium valves. I'm not sure why you would use them on stock Commando valves, but there may be a good reason. I just don't know what it is.

Ken

 

[swooshdave]

Can the valve tops be smoothed or is the hardness too thin?

 

[Fast Eddie]

I’ve always looked at lash caps as something else to go wrong... something else’s to fret / move / wear / break.

The thought was reinforced when I viewed Comnoz’ spintron videos, as the amount of unintended movement (flex, wobble, fretting, vibration, etc) of the valvetrain at revs really surprised me.

 

[Fast Eddie]

I’ve smoothed valve tips before on Triumphs and other makes quite successfully, but it has to be done on a proper grinder with fixture to ensure a perfectly flat and square face.

As to whether or not it’ll break through the hardness isn’t possible to say unless you know who made the valves etc.

If you have to pay an engineering shop to do this you’ll likely be a big step towards the cost of new valves. Given the cost of valves and the work you’ve got going on, I’d budget for new valves.

In fact, my strong advice would be to post off the entire head assembly to join your barrel in Sir Comstocks workshop and ask him to do ‘the works’ on it!

When Jim did my top end, the before and after dyno testing (with no other changes) was +9rwhp.

You don’t need to be a racer or hot rodder to notice, and enjoy, +9rwhp (that’s more than a 20% increase over stock).

 

[lcrken]

Can the valve tops be smoothed or is the hardness too thin?

They can, and it's a normal procedure during a valve job. My ancient Sioux valve grinder has a fixture for doing so, but I've also seen it done very nicely on a belt grinder, by hand).

Ken

 

[comnoz]

Nortons did not have lash caps when new.

I do not use lash caps because the Stellite tips on the Black Diamond valves last much longer than a lash cap.

The only time I used lash caps is when racing with Ti valves. Then the valves and lash caps got replaced every few races. Failure to replace the Ti valves at least a couple times a season has caused some major damage.

 

[swooshdave]

I’m hoping to avoid sending the head to @comnoz if I don’t need to. Not because he wouldn’t do an incredible job but I’m not sure I have the time or money right now. We still don’t know how much work the barrel I sent him will take.

If the valves just need touched up my local guy is more than capable. If guides or seats need done it’s going to Jim.