CB adjsuters w/1.25 rockers - no lash? What, now?

[deprivation]

I am doing the initial adjust on my valves and I can't back the adjuster enough to clear the valve stem.

The heads are AMC's, the rockers are 1.25's from Low Buggit, the adjusters are from CB Perf.

I thought I was supposed to back the screw off at TDC, then bring it in to contact and turn it 1.5 turns of preload. Anyone who's been in this territory?

A
_________________
1986 Westy 2WD auto a.k.a. "The Old Girl"
www.kittenfart.com

[D Clymer]

Did you install shims below the rocker shaft towers? Whenever you are using swivel feet you need to shim the whole rocker assembly up to allow for the extra thickness of the swivel portion of the adjustment screw.

Looks like you're close to being on the road again!

David

[deprivation]

Yep - I have the shims on - at least the ones that came with the adjusters. If I didn't know better (and I don't) , I'd think I need considerably thicker shims.

But it makes sense that I should be able to back the adjuster off to some lash. Gosh - could the pushrods be too long? Not likely. Hmm. Puzzler.

EDIT: I just measured the shims - they are the .06" shims, although my measurement put them at .057".
_________________
1986 Westy 2WD auto a.k.a. "The Old Girl"
www.kittenfart.com

[tencentlife]

When you're doing this combo, you have to mod the rocker arms a bit. On the underside of the adjuster end of each arm, notice the casting extends as a boss, making the threaded section a bit deeper. This raised boss has to be ground off until the underside of the arm on the adjuster end is flat all the way to the end. A bench grinder, or a high-speed angle grinder will do the job. This allows the extra room for the swivel-foot. After grinding all the arms, run one of the adjusters thru from the back side to clear the threads and clean them all thoroughly to remove any particles. You also have to use the .060" shims that come with the CB set under the rocker blocks. After that you will just barely be able to get freeplay at each valve.

This whole combo gets the valve geometry just about dead-on with a moderate-lift cam like the 2252 or the MV and stock pushrods. At half-lift, the adjuster shank and the valvestem should be at the same angle; when viewed from the side, it would look as if the adjuster was an extension of the stem.

Adding more shims would obviate the need to grind the arms, but then you end up with the swing geometry going "over the top".

You will need to set up your rockers on the shafts so that each one strikes its valve just sightly off-center laterally when viewed from above, it doesn't matter if it's left or right so long as they aren't dead centered. This induces rotation of the valve on each opening so they go round and round and wear their seats and guides evenly.

There is a sticky thread in the Performance/Engine Building forum here about valve geometry. If you want to indulge in hours of reading and become totally confused I highly recommend it, but there are a few useful pictures there that illuminate what I'm saying here. Or take the easy route and just follow my advice.
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Please don't PM here, I will not reply.

Experience is death to doctrine.

[deprivation]

[tencentlife]

All week, you mean. Do yourself a favor, my friend, and take them over to someplace that has a bench grinder. It takes about a minute each to grind off enough, but you'll be there forever doing it by hand.
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Please don't PM here, I will not reply.

Experience is death to doctrine.

[deprivation]

[tencentlife]

Definitely, the new grinder is far cheaper and much less painful than all those new tattoos you would need to complete the Popeye persona. I mean, forearms like a main mast with no skin art just looks, well, not nautical.
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Shop for unique and useful Vanagon accessories at the Vanistan shop:
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Please don't PM here, I will not reply.

Experience is death to doctrine.

[riceye]

[deprivation]

Okay - rockers are ground down and initial valve adjust is done.

BUT

As I was tightening down the rocker shaft, there was a pronounced SPROING and one of the pushrods hopped. Now that lifter is soft and a little bit of oil leaked out the oil pressure sender spot between the liter tubes on the opposite side.


I looked down the tube and the clip was still on the lifter. What the hell happened? Did the lifter simply pump down all at once or did I somehow break it?
_________________
1986 Westy 2WD auto a.k.a. "The Old Girl"
www.kittenfart.com

[tencentlife]

Nah, you just hung a pushrod and it popped. Even when you prefill them some will go soft while you build the valvetrain and load them. No biggy, they'll fill quickly on startup. Reset the clearance on the one that popped.

Better check that oil pressure switch is tight.
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Shop for unique and useful Vanagon accessories at the Vanistan shop:
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Please don't PM here, I will not reply.

Experience is death to doctrine.

[D Clymer]

[deprivation]

[Pascal]

Deprevation,

Could you post a picture of your modified rockers? So we can see a before and after shot? Are those the Rhino swivel feet and Rhino rockers? Thanks
_________________
'84 Westy - 2.2wbx, GT Torque-Biasing Differential
'91 EA Cabby

[deprivation]

[Pascal]

Thanks for the description. Sounds like there is not much room for the swivel foot adjuster to actually swivel even after the modification. Were you able to see the swivel foot actually swivelling after the valves were adjusted?
_________________
'84 Westy - 2.2wbx, GT Torque-Biasing Differential
'91 EA Cabby

[tencentlife]

Here's what you want to see:

Now these aren't an exact comparison; the left is a 10mm OEM 1.1 rocker, right is a 9mm Rhino 1.25. The actual height of the raised area under the nose varies. But you can see where the Rhino has been taken down to where the bottom of the rocker is straight across. Comparing heights between these two, left is 12.15mm, right is 10.7mm, so approximately 1.5 off is what you're shooting for.

This just allows you to get the slightest freeplay in the valvetrain when the swivel-feet are backed off all the way but still able to swivel some (if you back them further, the feet lock up against the underside of the nose), but the feet won't be running in that position, because from there you turn them in 1.5 or 2 turns or whatever your favorite amount of preload is (honestly, it makes no difference). You end up with a thread exposed and the foot is free to swivel in its full range. This is all assuming that the 1.5mm shim is also used under the rocker blocks.

It actually isn't strictly necessary to do this. You could just tighten down the rockers and some preload would exist and the lifters would adjust to that, but you wouldn't know how much and it would confuse the hell out of anyone who worked on the engine in the future, which someday might not be you.
_________________
Shop for unique and useful Vanagon accessories at the Vanistan shop:
https://intrepidoverland.com/vanistan/
also available at VanCafe.com!

Please don't PM here, I will not reply.

Experience is death to doctrine.

[deprivation]

[Pascal]

[mattcfish]