Don, did you put your finger over the return pipe in the frame to force more oil into the rockers? Usually done on a rebuild to fill the line and rockers with oil.
Without the hardened lash cap, what is the distance from the lower face of the rocker arm to the valve tip? I made EF adjusters for the twins but I think the valve tips have to be shortened slightly to make room like on the triples.

 

I seem to remember reading that the valve geometry of the big twins is less than optimal. Lash caps were supposed to improve the geometry if I remember right. I never pursued the topic further. But unless the caps were put on the valve stems, I cannot see how adding a cap to the adjuster stem would make any difference.

As for improved wear, if the mushroom adjuster is fully radiused, that would provide a larger radius and some minute increase in surface contact. I suppose that would reduce wear. Although the difference would have to be miniscule.

 

H overi Rob, Using marking pen on valve tip & turning motor is how I examined contact patch. Plus it makes visible rub mark on tip of valve stem.

The contact patch is exactly the same. The radius of mushroom is same as my original adjusters.

Regarding valve geometry, I'm close to center contact with valve % open. Triumphs are harder to adjust geometry. My head got .060 over intake valves against my will! I'm still furious about that! I used Kibblewhite black diamond valves.
In real life they fit differently the head is a bit thicker. So compensate for grinding seats. The normal diameter intakes were on back order so shop put in .060 over. I would have waited a year for them. I didn't want oversize. Anyway the exhaust stem height was good. The intake was low. So it got lash caps.

I got close as I could on geometry, without grinding stems or getting custom made pushrods. Thickness of cyl base gasket & head gasket is all part of this of course. I was not that committed to geometry to go farther than what I did.

Back to valve diameter, I can't really feel a difference. Larger valves reduces port velocity at lower rpm. I ride mostly at lower rpm range. 2500-4000.

Shop used Serdi machine. They cut seats narrower. BAD! I wanted full 3/32 seats. Wide seats cool much better, last much longer. Narrow seats good for high rpm air flow & that's it. Not good for long life & longest life is what I want. I very rarely even use 6000 rpm. It is what it is.

Will be interesting to track wear of KW lash caps. I expect the vavle stem will wear a point, the top of cap will wear a dip. If I had a spare lash cap I'd checked the hardness with a file. I didn't want to test the ones I installed as I didn't want to add a stress riser.
Don

 

Hi DM, Interesting photo, thank you. On left is worn out adjuster. T160 adjuster looks like radius is worn flat??
The T160 adjuster has my interest.... Why does it have the widened area near tip? I've never seen T160 adjuster before.

At the Porsche dealer I did many 911 valve jobs & full overhauls. Never once replaced an adjuster for wear, only when down shifting at too high rpm caused valves to hit pistons. However they got huge amount of oil supply.

I do not put finger over return pipe at first start. I pre fill return hose & oil feed to rockers. I oil rockers & stems just before start up. Then install valve covers.

Yesterday I observed how quickly oil started coming out ends of rocker arms. I started motor, by the time I looked at rockers they were already dripping oil out of ends.
Don

 

Hi Don,

T160 adjuster looks like radius is worn flat?

Uh-uh, flat is on a ball, flat sits on the valve stem, ball rotates in cup as the rocker end goes through its arc.

The T160 adjuster has my interest.... Why does it have the widened area near tip?

As I say, it's the cup enclosing the ball.

Snags with the "T160" adjusters (they were also fitted to late T150's) in real life are:-

. Too easy to set the adjuster/valve clearance on a spherical part of the ball; then, once the engine's started, the ball rotates and there's an enormous clearance between the ball flat and the valve stem.

. When the ball and/or cup wears, oil fills the gap; if you don't squeeze the oil out when checking adjustment, by tightening the adjuster on to the valve stem then loosening it to get the clearance, the running engine will squeeze the oil out, leaving a larger-than-intended clearance.

Hth.

Regards,

 

Hi Stuart, Thanks! Now I get it. It’s a swivel foot. Now photo makes sense.

I didn’t know Triumph did that. Getting sophisticated. Thanks for tip on adjusting. Triumphs demand careful attention, that’s for sure. I always wanted T160. My guess is if I get another bike it will be modern Bonnie.
Don

 

I added lash caps on my '72 T150 (adjusters as seen on the left above). This caused the adjusters to hit the rocker covers, holding the valves open. I chucked the adjuster screws in my lathe (lightly, using a piece of rubber fuel line to cushion) and turned them against a Dremel running a cut-off wheel (the ones that love to shatter) to slice the square drive from the top of each, then used the Dremel to slot the ends for screwdriver adjustment.

 

If you put on a lash cap without shortening the stem the initial contact point moves toward the rocker shaft.
I have not measured a stock arrangement so cannot say if this is better.
The left stock adjuster shows a basic problem with them, way too soft and wears a flat. When adjusted, the contact point works across the flat and clearances open up rapidly.
The T160 carries a lot of extra pork and still has the single downtube frame (yes, I know Slippery Sam was T150 based). A lot of weight can be carved off with a Wenco style frame (North to UK types). The crank can have 6 pounds shaved off and an aluminum clutch is another 3.

 

okay, ive never been able to figure this out. we re talking about various aspects of rocker geometry. the customary recommendation centers the adjuster on the valve stem at half-lift. this will allow the cam to transfer maximum lift to the valve. arranging the contact so that it is inboard or outboard ( closer to or farther from the rocker shaft at half lift) reduces the lift and changes the profile of the valve lift curve.

what effect does changing that contact have on torque? there are too many things going on for me to visualize this in my head. will a slightly too-long valve stem act like slightly too little valve clearance and boost duration and higher rpm power? how does changing the geometry move the cams opening and closing points? does changing the initial contact between rocker and valve change the average rate of valve opening in a useful way, even tbough you would be giving up lift?

or are the results of changing rocker geometry unpredictable?

 

Standard tappet adjusters do not give true cam profile lift. That's because as they wear, and a flat develops, in such a case the radius of the adjuster tip alters to less than the radius of the rocker arm, and hence the valve is momentarily allowed to recede after attaining full opening, this can not be adjusted out as part of tappet settings. However, the mushroom adjusters radius more closely follows the rocker arm radius, translating the 'correct' lift from the cam for the full duration of lift. The only way to correct this would be to have tappet adjuster or valve tip cam profiles incorporated to compensate, not easily possible as both components are rotational. That's the operation, whether this translates to hindered or improved performance is any ones guess. 🎲

 

Don reckons that the tappet radii are the same with standard and mushrooms. I deal with earlier adjusters, which have a virtually square end, so have a truly awful rocking motion causing guide wear. Maybe no advantage on a T140, but I do like the allen wrench adjustment.

 

Hi Mick, I can’t imagine Triumph would have ever fitted flat square edge adjuster screw. That’s very poor engineering.
I’ve adjusted valves with our type screw on many old cars, & Honda, BMW. I’ve seen lots of worn adjusters, but they all had radius when new.
Don

 

even if the stock adjusters have the same radius as the mushrooms, they still have to be made with a sufficient arc so that the edge of the adjuster doesnt dig into the valve at full open. are the small stock radiused adjusters wide enough?

how much extra is there? if you fit a higher lift cam will the stock adjusters still keep the curved face in contact with the valve tip at full lift?

i dont know, so i fit mushrooms to everything. they are definitely kinder to the valve tips, whatever the reason might be.

 

Hi, When both are new the original adjuster screw & mushroom gave exact same geometry. If, indeed the mushroom lasts longer, it can only be from better material or collecting more oil.

However if geometry is way off the Triumph adjuster can rock over too far & contact patch come off radius, meaning it’s pushing on square edge or screw. The large head of mushroom will help this. Doesn’t cure root problem but keeps off sharp edge.

Or the adjuster can run off edge of stem. Partially or fully. Mushroom could allow such bad geometry to be ran at least short term.

Another factor at least on paper, if geometry is off, it increases side loading if stem.

Web has much information on geometry & effects to valve opening.

Could I feel it they way I ride? Probably not. Low power you just give more throttle.

Cam grinders claim on the dyno & track the difference in performance is very important.

.070 low on intake stems put the stock adjuster right on edge of stem. Still it was on radius of adjuster tip though.
By dumb luck the lash caps are about .070” thick.
Don

 

Hi Speedrattle, Of course higher lift will increase rocker movement. Indeed that increases contact patch. Rocker geometry becomes more critical.
Is that enough to put tip of adjuster over its edge? I don’t know. Depends on lift. Also if geometry is correct. Certainly you’d want to verify that. The larger diameter of mushroom would be a must if Triumph adjuster is contacting past it’s edge.
Still the mushroom is sliding line contact.
My original question was why do users report longer service life? So long as Triumph adjuster is not falling of edge of stem or itself, it’s not contact patch.

On an aside, as Mick pointed out the Allen wrench adjuster works very well.
For racing, the mushroom is a bit lighter.
Don

 

My original question was why do users report longer service life?

Because they paid good money.

 

i think your observation about the oil is an interesting one.

 

There maybe more solutions than problems, but, I'm thinking Triumph's work quite well, but do suffer as Don says, when flats develop, mushrooms help .

Desmodromic, hydraulic, OHV, OHC, all attempt, and some succeed in solving the problems. OHV OHC gota be the best. Using Dons lash caps combined with EF foot adjusters could be good, neutralising the rotation of both contact patches and then allowing to combine with a cam profile between the two contact faces that corrects the valve wiping geometry that causes the problem. There's always the element of available space though, just a thought.

 

i remember hearing about a man who had a dead quiet moto guzzi. when my friend asked him why it was so quiet, he explained that he had modified the cases, oiling system, and valve gear to take chevrolet hydraulic lifters.

with enough improvements i could make my old T120 run, perform, and last like a honda. but then id have a honda, you know.

im reasonably tolerant of the idiosyncracies that come with the antiquated design of tbese things

 

interesting thread, but am wondering what EF adjusters are - the pic seems to show a hex head and ball in cup?
searched, but no joy
thanks
rory

 

EF = Elephant Foot. I think the name originated with the Porsche 911 adjusters. Ball and socket that covers the entire top of the valve stem. The "hex head" is the jet nut for tightening them. Lighter than a standard hex nut. Plus the screws have a hex socket for adjusting. The motion of EFs have to be checked when installing to keep them within the angle range of the foot. Otherwise the foot will hit the neck of the screw and tilt the foot off the valve. You will hear a loud slapping sound.
I started by modifying the rockers of my triple to use 911 (8 x 1mm thread) adjusters then decided to make my own with the correct 5/16"-24 and later made 5/16"-26 screws for the twins.
Having the contact point at mid lift square to the stem gives maximum lift. A 1" rocker arm moving +/-10 degrees gives 0.3473"of lift. Moving 20 degrees to 0 angle gives 0.3420"
As far as side thrust, although the maximum spring force is at full lift, the valve is not moving much and the acceleration is negative as it approaches full lift. As the valve is opening the acceleration is maximum and the adjuster is angled from the stem. Side force is going to be both the spring force and friction.
If these things had a real oil system you could put a hydraulic tappet in the spring collar.
Or, you could put in roller rockers like this:

The small shim is from a modern 600 and sits under the lash cap in the top of the spring collar.

 

Or, you could put in roller rockers like this:

and what, pray tell, dave, is that head off, and, how would you put a hydraulic tappet in the spring collar? i'm assuming that it could be done, but my experience is hydraulic tappets usually used in the pushrod gallery, eg harleys and chev ohv engines. would my 996 porsche have ef tappets, or just the air cooled ones?
thanks
rory

 

Hi Freakmaster, The only reason I used lash cap was the valve stem tip was too low. I don't know lash caps actually reduce stem tip wear or not. EF adjusters tend to reduce wear in my experience on 911 motors, but at the same time the head is basically oil cooled & has very high oil flow to rockers & valves. Same with Mercedes, the cams, rockers, valves receive huge oil volume. Very little problems with rocker tip or guide wear. These motors have good valve stem seals. When seals hardened or fail the motor will easily burn 1qt + of oil in 100 miles.

Automotive/motorcycle motor engineering is most interesting field. So many variables.
Don

 

Hi Freakmaster, The only reason I used lash cap was the valve stem tip was too low. I don't know lash caps actually reduce stem tip wear or not. EF adjusters tend to reduce wear in my experience on 911 motors, but at the same time the head is basically oil cooled & has very high oil flow to rockers & valves. Same with Mercedes, the cams, rockers, valves receive huge oil volume. Very little problems with rocker tip or guide wear. These motors have good valve stem seals. When seals hardened or fail the motor will easily burn 1qt + of oil in 100 miles.

Automotive/motorcycle motor engineering is most interesting field. So many variables.
Don

I added lash caps because the Stelite (or whatever was used) tips on my T150 valve stems was badly chipped and I didn't want anymore flakes getting into the system.

 

TR7RVMan's original post shows the same radius on a non-mushroom adjuster to the mushroom type, which would give the same rubbing pattern on the valve, as he wrote.

Some adverts for mushroom tappets say that the originals are square, with no radius (Mushroom Head Tappet Adjusters - Choose Make / Model / Year):

"The problem with the old style tappet adjusters is the design of the head. The head is flat and square. It does not contour the valve very well which "digs" into the valve stem and over time causing your valve stem to wear prematurely."

Are there more than just the two types of tappet out there (e.g. "square", non-mushroom rounded, mushroom rounded)?

This advert for 'mushroom' tappet adjusters Triumph has the benefits described as:

"The 1/2" radius has a larger surface which can help correct errors in rocker geometry, and have a smooth opening effect while being gentle on the valve tip."

Until I saw some videos that showed roller rockers being fitted to performance car V8 engines I hadn't realised that the rocker/tappet moves across the tip of the valve stem a small amount as it operates. I had previously assumed that there was a single point of contact on the tip as the valve is opened.

I found this old article that discusses this and also mentions things like the valve geometry and wear on valve guides related to the contact point of the tappet with the valve:

Roller rockers explained

Roller rockers aren't 70s disco throwbacks, they actually make your car run better. Here's our explanation why, as published in the May 2003 issue of Street Machine

www.whichcar.com.au

 

Hi Dave,
Is that a Mad Products conversion for a Nourish 8 valve head.
I’m Interested

 

🐘👞

 

That is the earlier Rickman-Triumph head. Originally had small screws over each valve. Did not like the screws or the 7mm stem valves. Changed to XR200 valves and reconfigured the rockers.
A SAAB 900 turbo is a good example of hydraulic tappets over the valves. Essentially, the spring seat would be changed to a tube for the tappet to run in. A chamber between the cam lobe (rocker in this case) and valve tip is filled with oil through a one way valve. The oil supply replaces the leakage.
Another version used by Suzuki has the hydraulics in the rocker. The rocker tip has a piston fed by oil through a one way valve. The piston replaces the screw in these engines. Probably an easier conversion since it just requires replacing the rocker. Requires a pressurized oil feed. Add the Elephant Foot to the end of the piston.
EF adjusters were used up to about '83 on the 911. I think they were changed to hydraulic after that because owners no longer wanted to do valve adjustments.

 

Here are the 993 hydraulic tappets in the rocker arm

 

Hi Don,
You did everything right with your head, apart from being ignored by the head company that fitted components larger than you wanted.
But you corrected it in the best possible way without having to resort to building up the valve stem tip with stellite.

My theory on the poor wear characteristics of the original valves and guides, is poor materials and poor design. If you use a point contact valve adjuster as Triumph do, then the tip of the valve needs to be very hard for a great depth, the originals were not and most aftermarket valves are poor.
Luckily you had the sense to ignore the cost and use Kibblewhite valves Don. These are known high quality and the same with the guides, not bashed in but fitted correctly and aligned to the seats.
You have also taken the time to get the valve stem height correct so your rocker geometry should be good, most people don’t bother to measure or adjust it.
The original adjusters have the same radius as the mushroom, so the rolling action is similar, what you describe as a "slide line" on the valve tip I believe is just the very high point pressure pushing through the thin, poor quality, hardened tip. Once through the edge of the adjuster digs in. The t150 adjuster in Daves photo I think has just collapsed due to it being too soft.

Good quality mushrooms have a large backing pad to absorb load and a very hard surface, they are not easy to make and require that the bits that need to more malleable be protected from the hardening process by copper plating.

Your very hard mushroom adjusters running on very hard lash caps and stem tips, in properly aligned quality valve guides, with correct geometry and an scroll oil feed, will outlast you Don.

One day Don, someone will buy or inherit your bike, and they will be the luckiest Triumph owner on this planet.

Regards
Peg.