Rocker geometry?

[Laxkraap]

Hey guys,is it normal to have to have the rocker shaft mounting blocks machined in order to center the rocker arms front to back?My rockers for the exhaust are about .080" off center,front to back.
I have Empi solid rocker shafts,if that helps.Or is the Empi shafts themselves that are 'off'(junk)?

Thanks,laxkraap

[Danwvw]

Wow 80 thousandths and you can't rearrange the shims and get closer? May need to not use any shims between the block and rocker that seems to work for me but I have CB-Performance Rocker shafts! Did need to push them forward or back a little and sand down one of the shims though to get the rockers to move freely without too much play.
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1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

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did you know they are supposed to be slightly offset? They are NOT supposed to be centered on the valve!
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[modok]

Yes it is normal.

[Laxkraap]

Danwvw..yes .080" and that without shims between stand and rocker arm.i tried to loosen the nuts holding the shaft to the head but i'm gettig no movement out of the shaft,front to back

John..I've read most of the rocker geometry threads i can and I get conflicting advise as to center or slightly offset the arms.So the valve will rotate?Or is there a different reason?

Laxkraap

[Laxkraap]

[mark tucker]

I like them in the center, but they dnt need to be,,,,for the most part, but yes Ive machined the blocks many times to get what I want side to side and in/out/up/down.side to side isant realy geo,...if there 80 I would machine it so I could use 2 .030's on thethrust side( toward the rear ofcar is thrust side). or more if tou can, but also look at your pushrod to tube clearance!!!! you have to have clearance there,thats more importaint.so determan just how much you can move it and have a safe margin oftube clearance.

[Laxkraap]

Hey Mark.thanks for the heads up on the pushrod to tube clearance.I'll check that out.

[Quokka42]

Pushrod to tube clearance is not a problem in the direction you are talking about, it should always be checked in the other direction with ratio rockers.

Yes, the offset of about 80 thou was built into the stock engine to encourage valve rotation, but becomes irrelevant when aftermarket keepers and valves are used, but it won't do any harm.
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There has only ever been one man who was perfect, and they nailed Him to a cross.

[Danwvw]

So 80 Thousandths at the valve? I thought your saying your block holes won't line up to the rocker studs by 80 Thou!
It takes quite a bit of luck or a really good selection of shims to get them set up nice. I always run into a conflict between (rocker to valve stem offset being nice) and (too loose or tight rocker play) and wind up compromising in favor of (rocker play being just right).
Just took this photo a few minutes ago, It's a type 1 engine mock-up showing #2 cylinder valves with Scat 1.25 ratio rockers, Looks like the valves are going to be rotating in opposite directions. Interestingly these Ratio Rockers are actually producing a lift 1.29 X cam lift.

_________________
1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[Laxkraap]

So is what your saying is that it is OK to be off center laterally,front to back of engine,but not vertically?Wouldn't this be putting unnecessary stress,load on the valve guide?
I thought that through proper rocker geometry we are trying to eliminate the stress to the valve guides,or am I just not getting it.
Or is one OK and the other not so much so?
Laxkraap

[Danwvw]

I defer to the experts, John, Mark, Modoc and Quokka42 there. But that sounds like what they are saying. That about 80 thousandths offset forward or backward is right! I don't really see a way to adjust the UP-Down much without making the holes in the rocker shafts and blocks bigger. (Maybe More square shims under the blocks)(I don't like too many shims under the block though, just enough to have about 1 turn or less of valve lash play)
My 1.25 ratio rockers above have about 1/16" vertical offset. I ran them that way for 25000 miles and have a valve spring removal tool on it's way from John with which I will be able to remove the valves and check the "guide ware" and report here. (It was not burning oil though!)
_________________
1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[Quokka42]

Your guide is probably fine - it's called a valve guide because that is what it does (in conjunction with the spring and retainer.) Valve train geometry is important in order to reduce stresses on the valve train, especially the pushrod, obtain correct ratio and reduce harmonics. Having an even wipe across the valve is just a useful way to observe it when using stock type adjusters, but in itself is only critical when using "elephant feet" or "swivel feet" as extremes of wipe can exceed their capabilities with high lift. The "elephant feet, or "porsche style" are particularly prone to failure if the fulcrum point approaches the edge of the valve stem.
_________________
There has only ever been one man who was perfect, and they nailed Him to a cross.

[mark tucker]

I didnt say it was right.but clearance at the pushrod tube is more importaint, as the tube will eat through a pushrod. I use large dia tubes so it's not a issue,but oe sized can be. I want my rocker as close to center as possiable,if it can move over then move it. I dont and wont use oe type pushrod tubes. also not all rockers have the same offset.thus moving them around may help but that also takes a lot of time unless you make a checking jig.also the rocker blocks can usualy be moved a few thou witch dosent help for this but it does help when doing side play. just be sure if you cut the sides of the blocks to keep them square to the shaft or exzisting serface.....shaft squareness is better as Ive had some that were not square to the shafts and thats not good.also had rockers that were not square to the shaft/bore. I also add atiny snake grove from the adjuster oil hole around the bottom of the rocker to the pushrod cup oil feed hole, I was building some hyd adjusters for these but never finished that project...couldent decide on what ratio.

[modok]

[Laxkraap]

First of all I have to say you guys are pretty freakin sharp!Thats why I post here when I have a problem or concern with my acvw and I keep notes for reference.
I do have one other question (for now) when setting rocker side play,is this done 'dry' ?

Thanks,laxkraap

[modok]

Should get the same results both ways. Less messy dry!

[mark tucker]

dry&weyt might varry .001" if you use thickoilglop. and as morlocl said it's cleaner. and stays cleaner too as oil picks up dirt&debris easyer and cant be blown off.never use any wd40 to clean or rince parts. I pulled a valve cover the other day just to check my side clearance..010 wouldent go so for me it's ok.... but even if if fit.....whoo ,makes the .767 shims??? Ill have to figure out withc hp-c vsi is that size and possiably cut down the od. it's always somethen.I have a very good selection on shims for the std dia shafts.I also forget I dont have that small oe size on my bugger.
getten back to dry or oily...do them dry then I turn them over and either inject oil through each pushrod cup or just fill each cut many times till the oil comes out the farther end of each rocker(ball on ball type or squirt hole on flat foot type...well mine have spirt holes tward the tip/spring locations.)just be sure they are fully lubed with OIL.

[dgsaz]

[challomoner]