Installing Mushroom tappet adj.

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northur

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Just had my 73 750 bottom end redone and put it back together last spring. Couldnt seem to qiuet the tappets to my satisfaction even tried to tighten up the adjustment 1 thou. ,so, I just bought a set of mushroom adjusters to replace the old original ones. I hate to have to rip the head off again, and thought I would feel some of you experts out ,as to wether they can be put on without doing a half a teardown.
 
At worst you will have to pull out the rocker shaft if you don't want to pull off the head. Seems to me a couple of them went in fine, but then I had the head off. Trouble is you can't screw them in from the top. Hope you don't have a messed up thread like I did. Had to buy a new rocker arm to get the new mushroom from Walridge to go in. The rocker was messed up, not the mushroom.

If you need to know how to pull out the rocker shafts, let me know, I've got a few tricks.

Dave
69S
 
northur said:
I just bought a set of mushroom adjusters to replace the old original ones. I hate to have to rip the head off again, and thought I would feel some of you experts out ,as to wether they can be put on without doing a half a teardown.
Click to expand...

Yes it's possible, as DogT said, it can be done by extracting the rocker spindles (heat the head first) and removing the rockers, but you need to be extremely careful not to allow any rocker shims and/or washers to fall into the head unnoticed, and it can be tricky holding them in position as the rockers and spindles are refitted.
 
You will have to pull the rocker spindles. Research this procedure. You will need a slide hammer with the threads to match the spindle threads. There are rocker spindle pullers that you can buy but the procedure will be the same. Loosen all adjusters to relieve pressure on all rockers. Heat areas where the spindles seat with a mapp gas torch and draw out the spindles paying attention to the placement springs and spacers. Replace spindle in same manner. Again, research this procedure. Or pull the head.
 
I've worn out a mushroom set, so ask where you found yours?

Use Caster oil based lube to ease getting the spindle back in, amazing in that use.
Don't pay any attention to the little oil hole in the head, go strictly by the cover slot alignment and put spindle notches outward to block most flow.
 
You might want to have a look at the adjusters and the valves before you swap in the mushroom adjusters. If the valves look good you might get the result you're looking for with new mushroom adjusters but if they are dented then maybe not. BTW, dented valves will have more clearance than what feeler gauges tell you is there, which can account for the noise. I tried a set of mushroom adjusters once and they didn't wear well at all. Last rebuild I used lashcaps and new mushrooms and they seem to be working out. Can't really see the wear surfaces but the clearances are holding ok after 6000mi.
 
I am not familiar with mushroom tappets and I asled myself where the benefit comes from.
Is it that the standard tappet in a standard factory configuration is not radiused properly to prevent the valve stem top end in some cases being touched by just the "sharp" edge of the tappet?
Or are mushroom only beneficial in non-standard configuration (high lift cams, etc)?
 
I think the mushroom tappet has a larger radius on the contact end which supposedly is supposed to spread the contact area over a larger area. After 13K on my 750, there were definite wear marks (dimples) on the ends of the valves and when Leo rebuilt it he suggested the mushroom tappets. You can get a set for about $35. Installation is another issue if you have the head on.

Installing Mushroom tappet adj.


Installing Mushroom tappet adj.


Dave
69S
 
Dog, those don't look like mushroom adjusters. Are hardened caps on stem? Sure don't look that hardened, at least after 13K miles. Should a dedicated owner just figure on replacement every two-3 rear tire changes?
 
hobot said:
I've worn out a mushroom set, so ask where you found yours? wallridge motors wallridge.com about 35.00 a set


Use Caster oil based lube to ease getting the spindle back in, amazing in that use.
Don't pay any attention to the little oil hole in the head, go strictly by the cover slot alignment and put spindle notches outward to block most flow.
Click to expand...
 
I thank you all for your input , here is what I wanted to hear,
unscrew the adjuster, push down on tappet .move pushrod out of way, pull tappet up, screw in said adjusters, viola.How about that HOBOT?
 
northur said:
I thank you all for your input , here is what I wanted to hear,
unscrew the adjuster, push down on tappet .move pushrod out of way, pull tappet up, screw in said adjusters, viola.How about that HOBOT?
Click to expand...
So, is that what you did or is that just what you wanted to hear?
 
unscrew the adjuster, push down on tappet .move pushrod out of way, pull tappet up, screw in said adjusters, viola.How about that ?
Click to expand...

Yes that is how I did mine, but on one valve I could not get space w/o the hardened cap removed and run w/o it. Never did figure out what caused this.
Peel engine got hard use but mainly I think the scoring seen on her valves and the messed up mushrooms was stuck throttle over rev event. Wonder if just radiusing the factory adjusters and then harden or nitride surface would do any good on hard caps of course.
 
Steve, no those aren't mushroom adjusters, they are the original tappets and valves after 13K.

Actually, taking the adjusters out, moving the push rod to the side and installing the mushrooms from the bottom of the rocker may just work. Hadn't thought of that.

Here's the mushroom one for reference.

Installing Mushroom tappet adj.


Dave
69S
 
Ok I misread what the 1st adjusters were, but recognized not 'shooms.
Some video on roller tip rockers shows they don't usually roll but are flat area to slide on. Its such a high load contact dry friction coats rubs right through fast.
 
bpatton said:
Last rebuild I used lashcaps and new mushrooms and they seem to be working out. Can't really see the wear surfaces but the clearances are holding ok after 6000mi.
Click to expand...

Got agree with, Bob I've always fitted lashcaps to my Brit-twins, I usually shorten the valve stem by at least the thickness of the lashcap. My Mk3 has had this mod including the mushrooms for close on 50,000 miles without a hitch. :D

Cash
 
Hi Cash,
how much id you take off from your valves tips (id what the thickness of lash caps , cause it's not beasy to take any measurements?.........I usually got mine from RGM, in Cumbria.........).
I imagine that when grinding out the valve tip , I could take out the treatment (if any) but so far , the lash cap will then take care of them, isn't it?
I am just going at noon, in UK at Hull to visit a double decker to bring back in frog land (out of topic , but should be fun too..)
pierre
 
pierre

Grief! it's been a year or two, I think it was 1mm, however I took more than that to help improve the geometry. I make up a spilt collet to support the valve stem in the lathe chuck and turn tip off. The case hardening isn't very thick, probably why it dents. I get most of my stuff from RGM they're just down the road.

My micrometer fitted in side the lashcap OK, other wise you'll need a bit of rod that will fit inside cut down to some suitable length and take the rod length off the combined measurement of the rod and lashcap. I hope that makes sense. :?

I might have a spare if I have I'll pm you the size.


Cash
 
Hobot, did you really do it that way ? I was sort of quoting a wet dream I had, but if you done it it certainly would save a lot of sarcastic words. By the way, I never heard of hardened caps ,where do you get those and do they just slip on?
 
northur said:
Hobot, did you really do it that way ? I was sort of quoting a wet dream I had, but if you done it it certainly would save a lot of sarcastic words. By the way, I never heard of hardened caps ,where do you get those and do they just slip on?
Click to expand...

Go to the rgm website and search their catalog for 050465.
 
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