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Mushroom valve adjusters

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#21 ·
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:
Image

The small shim is from a modern 600 and sits under the lash cap in the top of the spring collar.
Image
 
Discussion starter · #22 ·
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
 
#23 ·
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:

www.whichcar.com.au

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 www.whichcar.com.au
 
#24 ·
DMadigan said:
Or, you could put in roller rockers like this:
Click to expand...
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
 
#27 ·
TR7RVMan said:
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
Click to expand...
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.
 
#29 ·
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.
Image
 
#31 ·
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.
 
Discussion starter · #32 ·
Hi Peg, Thank you for the vote of confidence! My hope is to cover about 5 k miles a year. So it should only take 2-3 years to start seeing wear patterns.
I’m 70 now. Hmmm I bet the bike might outlast me!
The bike is very easy to start. I’m practiced at using either foot.
Wife & I are still in pretty good shape, so I might get another 10 years riding in. I hope so.
My wife & I, are of all things, ballroom dancers too. My dream is to dance at Blackpool. If not for Covid we’d had been to Blackpool & Vienna Austria. Isle of Mann races is on my bucket list too. Loosing 3 years at my age is hard to take. Will take another 3-5 months to sort Mom’s estate, then it will be fun time again.

So the bike is hopefully going to be good for quite awhile. Actually have a nice little 180 mile ride scheduled with a friend next week. He has customized Honda Fury 1300. He got it new, then customized it more. Really good looking. Perfect for looking cool in town. Horrible in the canyons! About as far from a Triumph as it gets. But we’re good friends & we make the route work out. He’s 70 also.
Wy wife calls me & my riding buddies the Geezer Gang. Pretty accurate!
We have to ride while we still can.
Don
 
#33 ·
Don, ballroom dancing, good for you My wife and I enjoy 50's rock and roll dancing...I just turned 75 a few days ago and can still ride at a fairly frantic pace on the back roads.But a terminal disease is putting an end to all this so enjoy it will you can
 
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#35 ·
Chaps,

The "Ball" in just visiting Blackpool Tower Ballroom has wandered wa-aa-ay too far off-topic from a thread titled "Mushroom valve adjusters". Please desist from further meandering or take it to a private conversation.

Regards,
 
#39 · (Edited)
I thought about swivel mushroom adjusters fot the race bike...Since valve wear is not a concern, it might be just something that can fail.....Many US OHV engines had shaft mounted rockers..These were quite reliable for 8000 rpm ....Most or all had one common feature..The adjuster was on the pushrod side of the rocker. The valve side had a radius machined into the rocker tip....In a perfect world so would Brit Bikes...Notice the 1.7 rocker ratio compared to Triumph 1.1
Image
 
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#40 ·
Truckedup said:
I thought about swivel mushroom adjusters fot the race bike...Since valve wear is not a concern, it might be just something that can fail.....Many US OHV engines had shaft mounted rockers..These were quite reliable for 8000 rpm ....Most or all had one common feature..The adjuster was on the pushrod side of the rocker. The valve side had a radius machined into the rocker tip....In a perfect world so would Brit Bikes...Notice the 1.7 rocker ratio compared to Triumph 1.1
View attachment 789249
Click to expand...
Other than the ratio, probably not that hard to achieve with access holes above the pushrods. Mind you, probably no performance advantage at all, just better guide wear!
 
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