Do lash caps result in non-standard geometry?

[Who.Me?]

Hi

I've bought a set of pre-assembled, stock style, EMPI 1600 dual port heads as part of my engine rebuild.

While checking some other info in the EMPI catalogue, I've noticed that they state that lash caps are also necessary because the valves are stainless steel.

Does that also mean that I'm going to have to sort out the rocker arm geometry as well because the valve stems will effectively become longer by the thickness of the caps?

I'm trying to build this engine as close to stock as possible and only make modifications to improve longevity and simplify maintenance etc., so I'd rather not mess with making custom push rods.

Is it acceptable to shim? I've seen posts against shimming, but I'm not sure if it's 'acceptable' or 'normal' practice in this case?
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Andy


Looking for info on my truck's history. Are you from Campbell California or nearby. Do you recognise it? ... http://www.thesamba.com/vw/forum/viewtopic.php?t=636786

[raygreenwood]

Unless these heads are made with a stock casting machined exactly the same as stock.....same spring seat pocket machining, same cylinder seat depth machining etc. Etc. Etc.......I would think there "could" be a decent amount geometry change required.

Yes.....you "CAN" fix it with shims....but only by so much. Shims move the rocker arms toward the valve cover. At some point tbey either start to ding on the cover or you hsve to start thinking of lengthening the push rods.

Personally....if I were going to go the route you planned to go.....I would have looked for a complete head that has valves with chromed stems and stellited tips. No lash caps required.

And.....the difference in cost for valves like that.....is probably about the same as the cost for a new set of custom pushrods (depending on what you use). Ray

[bugguy1967]

Check if the valves have hardened stems by using a magnet on the tips. If they stick you don't need caps.
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[mark tucker]

you should "sort out" the rocker geo weather you use them or not. I use them on every build I do. and yes they do change it. also the adjusters you use can/will also change it. and depending on the adjusters you use the rockers may need some machining to work right and help put the geo where it needs to be. if you want it to last do it right, do it 1 time and be done with it.

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[jeffrey8164]

What is complicating things are those EMPI (empty) heads.

If they say they require lash caps, why wouldn’t they come as a kit?

Are they supposed to be stock replacements?

It seems odd that they would make a stock replacement part that would require you to modify other parts of your engine but it is EMPI after all.
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[c77owen]

I can tell you that with those heads you DO need lash caps. I currently have a customer's engine torn apart with less than 500 miles that someone else built with no lash caps and these heads. Among many other build issues, a couple of the valve tips already have razor sharp edges. It would just be a matter of short time before catastrophic damage. I agree they should come with the heads when purchased, just like all of the studs, but none the less, they don't.

[KROC]

I believe Empi is assuming you would be using stock adjusting screws. If you use swivel feet adjusting screws instead of stock ones you do not need lash caps with stainless valves. ( just another option )

[mark tucker]

[Who.Me?]

[NJ John]

Rocker arms with the adjuster on the pushrod side can get a groove worn in them from the valve. Probably from a forged valve and non forged rocker. Not sure about forged on forged....
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[Who.Me?]

I knew these lash caps would be a pain in the arse, but it the whole lot seems out of whack.

Even without the lash caps, the rocker arms push on the valve stems with the adjusters fully wound in, so the valves never fully close. It's obviously worse with the lash caps on.

I measure the lash caps as 2mm thick, so going to have to shim a lot to get enough clearance to use the caps and get any adjustment. Not sure whether that's achievable without the adjusters contacting the valve covers.

I can understand the clearance issue with the lash caps on but the fact that the arms contact the valve stems even with the adjusters wound fully in seems odd. There was plenty of clearance and adjustment with the old heads.

The rocker pedestal heights are the same, and the brackets that hold the shafts are the same as another set I have. It looks like the valve stems in the new heads are about 0.5mm longer though.

To add to the annoyance factor, the head studs also contact the edges of the inlet valve rocker arms. Hopefully shimming will get enough clearance to sort that though.
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Andy


Looking for info on my truck's history. Are you from Campbell California or nearby. Do you recognise it? ... http://www.thesamba.com/vw/forum/viewtopic.php?t=636786

[67rustavenger]

Let's clear a couple things up.
Are the rockers, adjuster over the valve stem?
Or are they adjuster over the push rod?
What type of adjuster? Elephant foot? Ball? Stock adjuster pin type? Cup over the PR?
Are you trying to use the stock push rods while attempting to get the rocker geo figured out?

Post a pic or 100 of what your dealing with. It can help with understanding what you're up against.

Good Luck.
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[Who.Me?]

[67rustavenger]

Andy,
There's no real way to soften this.
But you may have to pull the heads and cut the head studs. So they clear the rocker assembly. You can pull the studs one at a time and cut them. Then reinstall them too.

Also, it appears that you are gonna need to make a custom set of push rods for your new heads. This could be caused by the fly cut on the cylinder side of the heads. It causes the rocker adjuster tips to be too close to the valve stem. Then the problem is compounded by the lash caps added thickness.

Do the push rods after you have the rocker geo figured and set. Then the PR length can be measured. You can cut the PR's yourself or if your confident that you have the length correct. Order a set from various vendors. Like ACN, Dan Ruddock, Smith Brothers.......
You'll need an adjustable PR to get the length figured out.

Sorry if it sounds like I'm raining on your parade. But this is what I'm observing from your pics.

Good Luck.
_________________
I have learned over the years.
Cheap parts are gonna disappoint you.
Buy Once, Cry Once!

There's never enough time to do it right the first time. But there's always enough time to do it thrice.
GFY's Xevin and VW_Jimbo!

[clonebug]

You might be able to fix it by adding swivel feet or elephant feet.

You may or may not have to grind/sand some off the bottom of your rockers on the adjuster side to make room for the swivel/elephant feet.

You will still need to do a geometry check but by adding lash caps, swivel feet and some shims under the rocker shaft you can move everything up and still get decent geometry without changing pushrods.

I did it on my heads with stock pushrods. I put 27,000 miles on it and saw no ill effects from it.
I ground I think about .050-.060" off the bottom of the rocker to move the adjuster up higher.....I never used lash caps at that time but I managed to use the stock pushrods with a higher lift cam.
Just check your half lift and pushrod angles to the adjuster and see if you can get something close with shims and adjustments.
It's not too hard but it takes a little time and a few setups in a bunch of different ways to find the best scenario.

Swivel adjusters are cheap and do work without lashcaps.
You will need a micrometer and magnetic stand to measure all this.
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[Who.Me?]

Thanks both.

Pulling the heads to shorten the studs isn't the end of the world. I reckon I could get them off without disturbing the barrel-to-case seal. Although I wonder if I'd be better off doing it in-situ with a dremmel cut-off wheel, if I mask the heads up leaving just the studs projecting? Less chance of metal flakes ending up in the cylinders?

I think my biggest concern is whether there's physically enough 'headroom' under the valve covers to shim the assemblies high enough to set the geometry. If it's a direct relationship, then I reckon I need to raise them off the pedestals by at least 3-4mm, which would risk them hitting the valve covers?

Unfortunately, I can't test that at the moment because the powder coater shipped my valve covers out with another customer's order by mistake. I may have to find some cheap ones just to mock it up to avoid delay.

If I have to arrange new pushrods, then so be it. I'd probably get them cut by someone else though. It seems pretty critical that they're all exactly the right length and I only have hand tools.

I've considered swivel- and elephant foot adjusters as others have said that they negage the need for the lash caps altogether. But again, it looks like they need to be precisely ground and I only have a basic, hobby bench grinding wheel.

If I know that shimming by that much is doable clearance-wise, then at least I could get on with the rest of the build and sort the geometry last.

Oh, and these heads weren't fly cut. I decided to stick with stock VW compression ratios.
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Andy


Looking for info on my truck's history. Are you from Campbell California or nearby. Do you recognise it? ... http://www.thesamba.com/vw/forum/viewtopic.php?t=636786

[Ohio Tom]

Stainless valves needed lash caps is an old wives tail.

Do whatever makes the geometry correct.

In order to do that, you need to know what to look for.
Lots of folks will have differing opinions on what correct geometry looks like.

Especially with stock rockers..
Especially with swivel feet...

Correct geometry may be hard to see thru the mess.

[ekacpuc]