Can I bend my rockers?

Rebuild reaching final stages now. Am on to the cylinder head, and wanting to centre the rockers on the valve tips. Some are a long way off centre. Not too happy with the spring washer thingies, thinking of making spacers instead, as per NOC notes. Said notes also talk of bending the rocker slightly. If this is possible it would simplify the arrangement of the spacers. But it sounds drastic. Has anyone done this?
Cheers
Martin

The spring should push rocker up against one side that is spaced to center on stems. Hi rpm racers use spacers on both sides of course. I've not heard of anyone bending them but imagine a hammer and a vice hit cold with a wood protector should work a treat for the amount needed if above don't do it.

While rockers in hand grind off the very ends to about flush with the socket push rod end which should allow push rods a clear path to place and not weaken the rockers one iota just relieve their inertia some.

Rockers (all engines, not just Norts) are purposely arranged off center to rotate the valves.

concours said:

Rockers (all engines, not just Norts) are purposely arranged off center to rotate the valves.

Click to expand...

That makes perfect sense. Thanks.

This does not seem correct..It does not seem to make sense. i have never heard of the valve end of rockers being offset to rotate the valves. it does not seem likely that a pushing action will impart rotary motion to the valves. this principle is sometimes used with pushrod camshaft gear to give rotary motion to the followers,or with overhead cams rotating buckets and therefore valves but completly different principle than rocker arms striking valves..

the principle of the rocker striking the valve IN THE CENTRE seems to be long established. the rocker moves in an arc, however so small, so there is no straight line push anyway. I dont think this small arc is enough to rotate the valves. to minimise valve and guide wear the closer to the centre in both planes would be desirable. you will get a rocking action in one plane anyway. to be really fussy the rocker arc travel length should be, in one plane only, distributed evenly about the valve stem centreline. This may show as a small length divot on top of the valve in the centre of the valve in one plane.

having said that , practically there are bikes running around with less than perfect geometry, some due to simply having repeated valve grinds.

However to purposely have offset striking seems incorrect.

As i am not the sharpest knife in the draw, I will accept corrections based on sound argument and evidence though. I have been wrong many times before and this may not be the last. What do the gurus say about this.
best wishes to all
Bradley

Good thing I have almost every size hammer ever made, I can whack and bend all kinds of stuff to "perfect" the geometry!

Yikes.

Sounds a step or two more drastic than downsizing one-piece rings to fit smaller bores and still have a measureable end gap...

Ya, know, these bikes seem to have run just fine out of the factory for quite a while. There are some things that can be improved and if you want to race or thrash them, I'm sure there are engine improvements, but I'm not sure I'd be going about re-engineering the rockers. Again, your mileage may vary and I wave my right to further consecutive interpretation.

Dave
69S

Rotating valves and lifters does not apply to our craft. As rare as this need to bend a rocker is I'd suspect a bad worn side of rocker or a bent rocker to begin with. It would take wearing away of head &/or the rocker side to shift them much off center. To get rotation in these places takes more than off centering, needs angles and bevels involved too.

Here's mine after 13K miles. I have mushroom adjusters on them now and new Black Diamonds.





Dave
69S

Norton valves are not intended to rotate. They do not have a rotator type cap or seat to allow it.

The rocker arms should be centered on the valve but since the rocker arms are case hardened I would not suggest bending them as that could easily start a crack.

Hardened spacers or washers are fine. Jim

Thanks for the advice guys. Now I think I'll go back to the NOC inspired direction of centering the rockers (except for the bending bit). It doesn't need to be perfect, but some were alarmingly offset with the spring washers in place before I stripped it down. I suspected the rockers could be case hardened, thats why I posed the question. Bending rockers seemed like a strange suggestion.
There is no sign of damage or excessive wear, its probably always been that way.

concours said:

Rockers (all engines, not just Norts) are purposely arranged off center to rotate the valves.

Click to expand...

Good ole internet,full of bullshit

OMG!!

What a bizarreness discussion... I am no rocket scientist ~ but the said "CIA Norton theory/ cover up" is staggering here ~ :shock: :shock: :shock:

I have a MAP torch, just maybe that would work eh !! We really need a techi-head guru to advise here ~ ???

Re: Can I bend my rockers?

by splatt » Sat Apr 14, 2012 9:17 pm



concours wrote:Rockers (all engines, not just Norts) are purposely arranged off center to rotate the valves.

Good ole internet,full of bullshit

Click to expand...

I too thought that all valves were turned by the rocker (or whatever was hitting it). I learned it in auto shop. Of course, I also learned that soon there would be a way to start a car by just pushing a button. I was told that the valves had to move to keep the seat clean and mated to the valve.

I'm still waiting for that button on my '73.

Diablouph said:

Re: Can I bend my rockers?

by splatt » Sat Apr 14, 2012 9:17 pm



concours wrote:Rockers (all engines, not just Norts) are purposely arranged off center to rotate the valves.

Good ole internet,full of bullshit

Click to expand...

I too thought that all valves were turned by the rocker (or whatever was hitting it). I learned it in auto shop. Of course, I also learned that soon there would be a way to start a car by just pushing a button. I was told that the valves had to move to keep the seat clean and mated to the valve.

I'm still waiting for that button on my '73.

Click to expand...

They are, some have mistaken the lack of elaborate mechanism to rotate as a lack of.... when the reality is it's a very simple, cheap, albeit lawnmowerish design to ensure the valve head, seat, stem wear as evenly (thus remaining sealed) as possible.

http://www.engineaustralia.com.au/downl ... /SB028.pdf

http://www.trw.com/sub_system/rotators

I would not say the valve could not turn some under certain circumstances but they were never designed to rotate on a Norton. There is no thrust washer or bearing or specially designed collet system to allow for it. Jim

That auto shop teacher really ot around. We must find this man and stop him! It was considered common knowledge that all valves rotated.

I can't speak for every head design but Norton twin valves don't rotate. All physical evidence shows the valves stay in one position and beat themselves to death.

mechanic matt said:

That auto shop teacher really ot around. We must find this man and stop him! It was considered common knowledge that all valves rotated.

I can't speak for every head design but Norton twin valves don't rotate. All physical evidence shows the valves stay in one position and beat themselves to death.

Click to expand...

Engines have done away with positive rotating valves since the elimination of lead in the fuel. Valve rotation leads to valve seat recession without the protective coating of lead. Diesel engine still use valve rotation on some engines. Jim

For what it's worth,
When I rebuilt my mk3 head after the new norton guides wore out, (rubbish), the experienced and trusted machinist who replaced the guides with Kiblewhite guides and black diamond valves made me lap and polish both sides of the spring seat and both ends of the springs so the valves could rotate without binding of the springs bottom and top.
I was suspicious that he was having a lend of me, but the valves do rotate, I've seen them (and cleaned up the oil from reving the engine without rocker covers)
graeme.

GRM 450 said:

For what it's worth,
When I rebuilt my mk3 head after the new norton guides wore out, (rubbish), the experienced and trusted machinist who replaced the guides with Kiblewhite guides and black diamond valves made me lap and polish both sides of the spring seat and both ends of the springs so the valves could rotate without binding of the springs bottom and top.
I was suspicious that he was having a lend of me, but the valves do rotate, I've seen them (and cleaned up the oil from reving the engine without rocker covers)
graeme.

Click to expand...

You are actualy refering to the springs rotating and takeing the valve with it, the valves colletes and retainers all lock up tight on most motors, some motors used collets that allowed the valve to spin others used special retainer cups, some used lash caps that released the collets, but they were all designed so the rocker should line up with the center of the valve