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Sun Jan 18, 2015 11:13 am

All,
I am having an issue getting my geometry set up just right. I have Steve Tims stage 2 heads, w120 cam, and I just bought the pro comp scat 1.25 rockers (adjuster on the pushrod side). I have everything set up right as for side to side play. My full lift measures out at .509". At half lift my push rod is in line with the adjuster like it should be. The only issue is the rocker foot is a bit forward on the lash cap. I would like the wipe to be centered forward and aft on the cap though. Any suggestions are appreciated. The way im figuring it, is there really is no way to get it to be centered if I want the geometry to be correct.

Sun Jan 18, 2015 11:39 am

The shims that come with the solid rocker shafts often are pretty limited. I have had to sand them down to find combinations that fit mine. But aren't the rockers supposed to be a little forward or aft. Not dead center? I don't know 1.25's are probably going to set pretty high on the valve stem and that should rotate them so I don't see why you could not set them centered as far as forward and aft goes. What would look nice is if they were all just a little forward. Probably not going to happen though without sanding down the rocker blocks though.

Sun Jan 18, 2015 11:57 am

FMXtreme83 wrote: All,
I am having an issue getting my geometry set up just right. I have Steve Tims stage 2 heads, w120 cam, and I just bought the pro comp scat 1.25 rockers (adjuster on the pushrod side). I have everything set up right as for side to side play. My full lift measures out at .509". At half lift my push rod is in line with the adjuster like it should be. The only issue is the rocker foot is a bit forward on the lash cap. I would like the wipe to be centered forward and aft on the cap though. Any suggestions are appreciated. The way im figuring it, is there really is no way to get it to be centered if I want the geometry to be correct.
Just because your pad isn't over the center doesn't mean your geometry isn't correct , geometry is one this , centering the pad is another ... it doesn't have to centered ...

Sun Jan 18, 2015 12:20 pm

In a perfect world, they'd wipe equal distance from zero to full lift, but it's not. Just do geometry as best as possible, and let the pad fall where it may.

Sun Jan 18, 2015 2:40 pm

hmm this sounda like an old dollypardon song...hear we go again doot da doo........so...what does the adjuster being inline at 1/2 lift have to do with any thing? left ...right... for the most part atleast 1 shim on the thrust side,2 is gooder 3 is better. but make sure you have pushrod tube clearance throught the lift cycle. add lash caps, and no shims under the rocker blocks usualy workd good.milling .040 usualy works better.

Sun Jan 18, 2015 5:00 pm

mark tucker wrote: hmm this sounda like an old dollypardon song...hear we go again doot da doo........so...what does the adjuster being inline at 1/2 lift have to do with any thing? left ...right... for the most part atleast 1 shim on the thrust side,2 is gooder 3 is better. but make sure you have pushrod tube clearance throught the lift cycle. add lash caps, and no shims under the rocker blocks usualy workd good.milling .040 usualy works better.

I was just saying at half lift the rocker arm geometry is correct. In every book I have read and any research done, it all says to make sure at half lift the push rod should be strait in line with the adjuster ( no angle between them). I am running no shims with lash caps. I dont quite understand what you mean by 2-3 shims on the thrust side? My side alignment is correct. The foot is off centered sightly to help with valve rotation.

Sun Jan 18, 2015 5:39 pm

Do not trust the adjuster to be in line with your pushrod at half lift.
Why? Because the rocker may not be correctly manufactured, and even if it is - that would only be for one particular lift. Do you have the standard lift?

Sun Jan 18, 2015 5:46 pm

You have to visualize a point in the center of the pushrod/adjuster articulation, and draw a line from there to the center of the rocker shaft. Draw another one from the same point to the contact patch on the valve. The valve spindle is the last line.
These are what you work with. There are no shortcuts.

Sun Jan 18, 2015 8:36 pm

what book?? for what engine? and the date on that book is????there are many different rockers out there.the pushrod has a ball on the end and the rocker has a adjuster with a cup on the end.thats kinda hard to effup, that portion isant realy a geo worry it's the other end the end on the valve that needs to be a whole lot closer then the pushrod end.I like mine more inline at about 3/4 lift or more.

Sun Jan 18, 2015 11:03 pm

Get your swipe where it needs to be. Usually no shims and or have the blocks milled. I'm with Mark on this one, I'd rather it be straight when the spring pressure is higher. My last set of heads were Tims stage II's and I had to mill the pads, .065. Lower rockers will bring the swipe pattern down, away from intake side of head. Thicker lash caps have the same effect. Berg sells thicker ones.

Mon Jan 26, 2015 7:44 pm

mark tucker wrote: what book?? for what engine? and the date on that book is????there are many different rockers out there.the pushrod has a ball on the end and the rocker has a adjuster with a cup on the end.thats kinda hard to effup, that portion isant realy a geo worry it's the other end the end on the valve that needs to be a whole lot closer then the pushrod end.I like mine more inline at about 3/4 lift or more.

Sorry to butt in, but I,m new at this also. Wondering if anybody might have a real good explanations of the procedures and even some pics of proper geometry. I'm using the same scat rockers but in the 1.4's and if I'm correct I think I need to machine my blocks down.

So I guess what I'm asking is, what do you mean by (In line)? Do you mean lining the rocker tip to the center of the shaft at a 90 degree to the valve?

If so, at half lift, mines past that to about 105 degrees

Mon Jan 26, 2015 8:28 pm

zbug wrote: mark tucker wrote: what book?? for what engine? and the date on that book is????there are many different rockers out there.the pushrod has a ball on the end and the rocker has a adjuster with a cup on the end.thats kinda hard to effup, that portion isant realy a geo worry it's the other end the end on the valve that needs to be a whole lot closer then the pushrod end.I like mine more inline at about 3/4 lift or more.

Sorry to butt in, but I,m new at this also. Wondering if anybody might have a real good explanations of the procedures and even some pics of proper geometry. I'm using the same scat rockers but in the 1.4's and if I'm correct I think I need to machine my blocks down.

So I guess what I'm asking is, what do you mean by (In line)? Do you mean lining the rocker tip to the center of the shaft at a 90 degree to the valve?

If so, at half lift, mines past that to about 105 degrees

http://www.superbeetles.com/performance101/aug.htm

Mon Jan 26, 2015 11:34 pm

i read that link.... I dont think he has a clue. when using 1.4 's add a .060 shim...but that will cause coil bind??wtf?? why add a shim? he hasent a clue about geo or some of his wrightings are not there.sorry to be blunt but thats how I read it. I think he is trying to repeat what he has heard or read in a old book.
3 shims on thrust side,for better thrust control.you may have to mill the block sides or end caps to get this. do it or dont I dont care.why does the flywheel have 3 shims??(BTW I was doing this on my shaft rocker v8's long before I got into performance vw's ) no shim you have 2 thrust serfaces at the same speed handling the load.add 1 shim you now have 4 serfaces and reduced speed, add another and you have 2 more serfaces to handle the load&even farther speed reduction at each serface.
As for the pushrod being inline with the adjuster I could care less where it ends up, it has a ball and a socket, pretty hard to eff up that geo.it's the valve end geo that counts.(oe type rockers are a different matter and both ends can cause issues in some instances) you do not want the rocker running off the end of the foot at full lift or pulling the valve stemtward the shaft.too high a shaft will do this with some cams. even with low lift cams Ive had to lower the rockers for what I see as best geo for the application.not much but a little. diferent makes take different things as does diferent cams,valves,heads etc. there is NO majic spot for any of them to be right on all engines.but most are close when used with new parts at the oe spec stem hights, is close good enough??for some yes for others no. for me I want it where I want it, as I do not worry or think about it after it's done.I go have fun and forget about it.do it right do it once.if your second gessing your self somethen isant right...kinda like my spellen.

Tue Jan 27, 2015 2:18 am

Rockers geo using pushrod side adjusting screw:

http://www.thesamba.com/vw/forum/viewtopic.php?p=7004861#7004861

:wink:

Tue Jan 27, 2015 4:09 am

What Vince's shows effectively is how difficult it is to accurately eyeball this method, but he ends up with the adjuster parallel to the pushrod anyway.

If your offset is a bit off-center it probably won't change with a change in geometry - unless the rockers are poorly machined, or you have gone beyond an acceptable range.

Tue Jan 27, 2015 8:14 pm

Wow!! Thanks. Thats alot of info. Anybody want to do mine for me. :D

Actually, I think mine are real close to what Mark Tucker is talking about with no shims underneath. Thanks

Wed Jan 28, 2015 3:46 am

To have done all the things Mark claims to have done he would need to be a nonagenarian Nazi - but whoever heard of a German who hates engineers/engineering?

Mark is quoting stuff he has read regarding Chevs, a completely different animal to the VW. Follow his advice at your peril.