Lash caps. Any good?

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Fast Eddie

Fast Eddie

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I’m not totally happy with the tappet to valve relationship on the stage 3 Maney head I’m currently playing with.

I’m predisposed to being against lash caps as it just seems like an extra thing to go wrong / fail etc.

But I’m thinking they would help in my current situation.

Anyone on here use them? Any feedback or experience to share?
 
Yeah, I have used a caps from a few different suppliers.

They all wore pretty fast on a Norton and needed to be replaced regularly but other than that they work fine.
 
No experience with them on a Norton but plenty on US V8 motors. Never thought of them as useful to correct a geometry problem but suppose they could under some conditions. Some years back, stellite-tipped valves were a hot item on pro-stock and other high-load valve trains but it was found that they tended to break under some conditions. Lash caps were useful to prevent that. Of course, if somehow the valve lash goes to h3ll, the cap can pop off and end up...???

I don't know if it's the issue you are concerned with but when I rebuilt my 850 I was not happy with the angle that the rocker hit the valve. It was way off center (slightly off center is normal with many engines to ensure valve rotation) but this was far enough IMO to put excessive side load on the valve stem which would, in turn, cause abnormal stem/guide wear. I briefly thought about lash caps but since they would not have changed that side loading, I didn't install them. I did the commonly mentioned rocker adjustment with shims to improve the rocker/valve stem alignment to where I felt is was OK. I guess you've already looked at that?
 
My issue is that the tappet is not in the centre longitudinally, or fore and aft, or North /South. Almost as if the rocker arm is too long. Side to side alignment is good.

I’m pretty sure it’s due to the big valve re angle job that was done on the head by Steve M as part of the stage 3 spec.

Don’t get me wrong, it’s not massively out. My thinking was that lash caps might help ‘spread the load’ and reduce any effects of a slight miss alignment.

I’ve no idea if all Maney stage 3 heads are like this? But sending it back to him isn’t really an option if I wanna use the bike this year. Which I do!
 
Here’s a pic that might make more sense than my waffle above!

Is this normal for a Maney Stage 3 head?

Will lash caps help elevate any symptoms?

Am I over thinking this (again)??

Lash caps. Any good?
 
comnoz said:
Yeah, I have used a caps from a few different suppliers.

They all wore pretty fast on a Norton and needed to be replaced regularly but other than that they work fine.
Click to expand...

Thanks Jim.

Which were the best out of what you tried ?

Any comments on my pic above ??
 
Put a really light spring on the valve so you can stroke it up an down with finger. set head on boards so valve has room to move. Put rocker on and stroke about 10mm with finger on adjuster. Watch the contact center through motion. move adjuster to simulate different length pushrod.
 
I have done that with cut down carb springs and 3 different pushrod lengths: stock, -0.040” and -0.100”.

Having played with them all, my conclusion is that it looks like shortening the valve will give the best outcome. This will of course remove the Stelite tip.

The lash caps I have are .080” thick.

My thinking is to hack .200” off the valves and use lash caps and have a net reduction of .120”.

This will allow the tappet to protrude through the rocker some .200” and, due to the angle of it, put the contact patch closer to the centre of the valve stem as it opens the valve.

This, along with the lash cap load spreading theory, should satisfy me... I think.
 
From your picture i'd say its better to be off in that direction than getting close to the edge on the other side when valves open. Does the contact point cross the centerline of valve when full open? If so i'd say run it and if it wears too fast fix it with lash caps then
 
Danno said:
Anyone try the ball-and-socket tipped lash adjusters (like Triumph)?
Click to expand...

Yes.

The Trident type with captured balls don’t handle big cam lifts well and can cause problems.

Porsche ‘elephants foot’ type are better in this regard, but are heavy.

Some Rotax engines use a similar, but smaller and lighter version of the ‘elephants foot’ design but the thread and size is wrong. Dave Degens used to turn them down, and insert them into a threaded sleeve for Triumphs. A lot of work, but they did work well.

I didn’t want to go that route on this job though.
 
edgefinder said:
From your picture i'd say its better to be off in that direction than getting close to the edge on the other side when valves open. Does the contact point cross the centerline of valve when full open? If so i'd say run it and if it wears too fast fix it with lash caps then
Click to expand...

Thanks, good input, I’ll have another look when I’m next in the shed. I’m ‘shipping out’ for work for a couple of weeks now though.

This work lark don’t half get in the way of my motorcycling...!
 
I just managed to have another look. No, the contact point does not cross the centre of the valve, sadly.

But then it’s not on the edge either.

Extending the adjusters through the rocker by shortening the valve, as I mentioned above, would make an improvement, but so small its hardly noticeably and doesn’t seem worth it, especially as it would necessitate lash caps and introducing another potential failure mode.

So, on balance, I think I’ll run it like it is.

This is what happens when you over think things folks !
 
I used lash caps on mine because of a geometry problem where the hard end of the valve was ground off. The first ones wore too fast and had a hole in the center is where all the wear started from. The ones with the hole in the middle also took out the tappet adjusters. Now I have some good ones with no hole and a Rockwell hardness of 60. My valves stay in adjustment for thousands of miles. No perceptible wear on the tappets or lash caps last time I checked. I think Kibblewhite is supplying these now.

Wouldn't it be a slight advantage to have the wear line cross the valve just off center? That would effectively make the valve spin just a little and spread the wear out over the whole surface as well as keeping the valve seat in good shape.
 
motorson said:
Wouldn't it be a slight advantage to have the wear line cross the valve just off center? That would effectively make the valve spin just a little and spread the wear out over the whole surface as well as keeping the valve seat in good shape.
Click to expand...

That is a standard method used in many engines to make valves rotate without adding any components to the valve train - rotocaps, etc. The valves must rotate to ensure longevity and good sealing over an extended period.
 
Thanks Jim, I’ve kinda realised that!

I think I’ve managed to find the best pushrod lengths to achieve the best contact I’m gonna get and will run it without resorting to lash caps.
 
Nigel , I used lash caps on the exhaust Vv's on the race bike RH10 head to get the RHS exhaust stem to tappet alignment better.( Fore and aft alignment was out)
The Vv's are Black Diamond items.
I found that the lash caps eroded the edge of the Vv stems slightly, whether due to Vv bounce (it is rev limited in the ignition to 7450 rpm and sees 7000 rpm at times )or flutter not sure .
They are really short ones from JS Motorsport.
I am using the FA head at present without the lash caps.
Regards Mike
 
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