Elephant foot tappets

SteveBorland said:
I wonder if it's possible to use the T160 captive ball type on a Norton then?
In the triple world, owners are not 100% positive about them, there are reports of the ball moving when adjusting the tappets, so that the clearance ends up as far too much, and some report cracking on the cup.
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Well, first you’d have to ascertain if it’s the same thread (LAB?), then do something like shorten the valve stems to create space, then mock it all up and see if the range of motion is ok (ie not fouling the ‘cups’).

When all that’s sorted, you still run the risk of experiencing the issues that many triple owners did !
 
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jseng1 said:
Here's his drawing of the complete valve assembly.
Elephant foot tappets
Click to expand...
Are those stock valves or shorter?
 
Fast Eddie said:
Well, first you’d have to ascertain if it’s the same thread (LAB?), then do something like shorten the valve stems to create space, then mock it all up and see if the range of motion is ok (ie not fouling the ‘cups’).

When all that’s sorted, you still run the risk of experiencing the issues that many triple owners did !
Click to expand...
Someone made ones for Commandos once, got a set in mine but I don't think they're available any more, at least I haven't seen any for a long time. The head is larger than standard so you need shorter valve stem to keep the geometry somewhere close to standard.
 
Hi guys,

I would like to steer this discussion back on track. Although related, the captive ball tappet Triumph fitted is an inferior design to the EF tappet, and not the subject of this discussion.

Hopes of fitting those to Norton rockers is futile, as the thread type used by Triumph is 5/16"-24 TPI UNF, while Norton kept to 9/32-26 TPI CEI.

I am looking at ways to fit the original VW/Porsche tappets (thread type M8x1), and it seems making new rockers is the best solution. Dave Degan's solution depicted by FE looks bodged to me.

Geometry has to be verified wrt angle between tappet screw and valve tip, and this is best performed by CAD for various lifts.

- Knut
 
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mdt-son said:
Hi guys,

I would like to steer this discussion back on track. Although related, the captive ball tappet Triumph fitted is an inferior design to the EF tappet, and not the subject of this discussion.

Hopes of fitting those to Norton rockers is futile, as the thread type used by Triumph is 5/16"-24 UNF, while Norton kept to 9/32-26 TPI CEI.

I am looking at ways to fit the original VW/Porsche tappets (thread type M8x1), and it seems making new rockers is the best solution. Dave Degan's solution depicted by FE looks bodged to me.

Geometry has to be verified wrt angle between tappet screw and valve tip, and this is best performed by CAD for various lifts.

- Knut
Click to expand...

Sure, make new rockers. I mean, why on earth not ?

Crack on.

Let us know when you’ve done…
 
What is used in the valve train probably depends on the cam lift rates and the max. revs to be used. My 500cc short stroke Triumph motor used to rev to 10,500 RPM and had slow lift rate cams with long duration. I used Wassel adjusters which were hollow and adjusted with an Allen key. I used steel lock nuts which had about one third less thickness. With a normal road bike, weight in the valve train probably does not matter as much.

I cannot remember the brand of the valve springs, but they were American.
 
acotrel said:
What is used in the valve train probably depends on the cam lift rates and the max. revs to be used. My 500cc short stroke Triumph motor used to rev to 10,500 RPM and had slow lift rate cams with long duration. I used Wassel adjusters which were hollow and adjusted with an Allen key. I used steel lock nuts which had about one third less thickness. With a normal road bike, weight in the valve train probably does not matter as much.

I cannot remember the brand of the valve springs, but they were American.
Click to expand...
US Companies that made Valve springs in the 'old days" is S&W,

in the 1980s R/D, Founded in 1981 by Donn Rickard and Jim Dour of Megacycle Cams, California-based R/D Valve Springs has valve spring kits for vintage British, Italian and Japanese motorcycles, and also supplies individual springs and valve guides, valve guide seals, plus shims, lash caps and buckets for overhead cam engines. R/D valve parts are designed, engineered and manufactured in-house using only the best high-quality materials including 6AL4V titanium, 4140 Cr Mo, AL Si bronze and 7075 T06 aluminum. Kits start at $112. Honda CB350 twin beehive kit shown.

also PM Precision Machining makers of Black Diamond valves.

OEM Norton valves springs have good basic spring pressures and seem to last a long time. Commandos don't need real strong spring rates.
 
Carl,
It appears that R/D is out of business which is a shame. I used their components for many years and you're right, they were the absolute best. I would guess that PM springs are about equivalent.
 
I am wondering what people are trying to achieve by changing the tappet set-up. I do not even know what cam is in my motor. When I had it ground, I just asked for the best Norton grind - it is probably 650SS. All I know is that when I use it the motor is very strong from 5,500 RPM to7,300 RPM, and is reliable. The motor is very competitive, but must have close ratio gears to be effective. With wide ratios, it is hopeless. I can understand why people like old Commandos as road bikes - they are what they are and not something else - completely rebuildable and not throw-away items.
 
I just stick to my original valves, rockers and adjusters, been working fine for 49+ years, but have replaced the springs, all valves seal good and run fine with my 2S cam grind, have replace the guides 3 times 2x by what a butcher did the first time, pushed the new guides in cold, the 3rd time by me and the head was shaved on a milling machine at work with a hand made cutting tool, but that was a long long time ago.
The original valves seem to run and seal OK on unleaded fuel and the original adjusters seem to sit right on the valve.
 
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