Rocker Geometry

[Ghia Nut]

I am looking at upgrading to cb 1:1.1 super stock rockers that are bolt together. I also would like to get Manton chromolly push rods. I really don't want to fool with cutting push rods or shimming as that's why Im staying with 1:1.1.
What length push rods do I need?
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'59 typ1 rajay turbo
'72 Ghia rajay 1641 dual 36DRLAs, 1 3/8" SS merged header and fat boy
78" GL Vert with ej22t swap
This will likely change tomorrow to something else.

[mark tucker]

so what makes you think 1.1 wont need any thing????it will.

[Ghia Nut]

Because they are stock specification? Besides VW wouldnt custom cut each set of push rods to each engine, there was a set length.

Obviously aircooled.net has these lengths set in stone.
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'59 typ1 rajay turbo
'72 Ghia rajay 1641 dual 36DRLAs, 1 3/8" SS merged header and fat boy
78" GL Vert with ej22t swap
This will likely change tomorrow to something else.

[mark tucker]

stone? what do they use a stone for?pounding sense into somebody's head that thinks everything is exzactly as vw intended it to be? oe cylinders?oe heads ?correct heads that havent been cut?, no valve work at all? all the correct valve hights?, the correct lifters?the correct cam?no wear on any parts at all? no machine work at all on any parts?boy they must have a big box of boxer stones.wonder where there stones are made?

[Ghia Nut]

I would love to examine my engine at the molecular level but there are more important things in life...

So I guess you are saying that every VW person should check over their valve geometry on a stock motor, even the one new in crate from VW?

Apparently I have been putting engines together wrong if I don't check rocker geometry on stock push rods and stock rockers that came from the same engine, and measure down to .001 tolerance on the top end

Why would cb or any other company for that fact reinvent the wheel of design for a stock 1:1.1? The relation of the adjusting screw to the socket for the tip of the push rod can not change.
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'59 typ1 rajay turbo
'72 Ghia rajay 1641 dual 36DRLAs, 1 3/8" SS merged header and fat boy
78" GL Vert with ej22t swap
This will likely change tomorrow to something else.

[MURZI]

I will chime in.... On the 1679 I built, referenced in another thread, I used a w100 cam, stock rockers, and aluminum pushrods. The cam should measure .420 lift right?? Well it did not because of the head flycut and the geometry was way off...it measured 460ish. I had to shim the rocker blocks with a .060 shim to dial it in. Had I not checked this, the guides would have wore out very quickly.

On even a stock engine, you should check geometry. Cylinder length, head flycut, rocker pad placement and height on new heads, head design(step or no step) and even rocker arms can change things.

Mark is right.....
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62 vert
2276
Tim’s welded heads
45 Dells
A1 sidewinder
Fk44 cam

[Ghia Nut]

Thank you, I don't mind being rapped across my knuckles as long as it is explained.

Is other at least a base "close to stockish" size that I should get before I make a purchase?

P.S stock cam stock lifters, 87 jugs, drd heads with ss 40x35.5 valves, no spacers or shims.
Also going to single HD springs and removing the inner spring for now. Limited to 4500 rpms.
_________________
'59 typ1 rajay turbo
'72 Ghia rajay 1641 dual 36DRLAs, 1 3/8" SS merged header and fat boy
78" GL Vert with ej22t swap
This will likely change tomorrow to something else.

[MURZI]

Looking at some of your posts it looks like you are running a stock cam right? I think you will be fine with the CB rockers and Manton pushrods. Just check everything when you put it together. You may have to dial it in with rocker pad shims to get it "perfect"....but that is easy.
_________________
62 vert
2276
Tim’s welded heads
45 Dells
A1 sidewinder
Fk44 cam

[mark tucker]

so where are the drd heads made?and did they cut any off them?I think you missed the point, but thats ok I dont mind I see trashed parts all the time from somebody that thinks it's all good.


do it right, do it once ,be done and go have fun. or make a life time comitment of effing with it&emptying your wallet. if you dont know how or are skeered or dont have to tools, get help from somebody that you know for a fact does posess all of these. you apparently dont under stand all of the varriables.if they all stack up one direstion trubble is on it's way, if they alternate it may be just fine..... but this is september not may.check it all. and dont wory about the small stuff like each pushrod being exzactly the same,I like them to varry about .010" because everything else does .I have had way to many rocker arms of the oe style including oe rockers that had different cup hights... and not by a little either. good luck and remember shit happens(or so I have heard)

[mark tucker]

also I think the cb add says they have totaly reenigenered the oe type rocker!! or something like that. wonder why? if it was perfect.

[modok]

in response to a challenge from x-file, something to do with.......a brick? (some OZ thing)
I submit "scientific proof" of.........well what happens when you look at a rocker.

When the adjuster is in the "normal" position, the centerline of the adjuster's threaded shaft forms a tangent to the pivot point's arc, this is due to the way a OE vw rocker is made.
tangent means, well........ look it up.
Thus you can use this to eyeball the geometry; correct should be in line or parallel to valve at half lift if shooting for 90 degree at half lift.

If the adjuster is backed out, or extended from it's normal position then of course it will not be exactly at a tangent. Take that into account.

More extensive study here:
http://www.thesamba.com/vw/forum/viewtopic.php?t=3...mp;start=0
If skyto's excellent image disappears let me know, I saved it.

[mark tucker]

and that makes it perrfect how??with what lift?change the lift & your little lines move around&nolonger line up so neetly.(not to mention the lines will be washed away with the engine running&oil splashing around). so iff your way off at full lift or when the lift cycle starts your good to go as long as the lines arnt blured& you stop at half lift.....if only it were that simpleand only 1 cam&set up hight was used on all engines.

[Dr OnHolliday]

[Quokka42]

With the rocker assembly too low, the pushrod is acting on the wrong circumference of the rocker, so the cam's lift is multiplied by a larger amount. The adjuster can also be extended too far, especially when swivel or elephant feet are used. A common occurrence, really, often blamed on the parts.
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There has only ever been one man who was perfect, and they nailed Him to a cross.

[x-file]

[Quokka42]

No, because you are making false assumptions based upon stuff you have read on the internet. If people try to follow your advice they will likely produce a situation where the swivel hits it's limit, which can be seen if you follow the links and look at 0 and full lift. The thrust that you read about does not play any real part provided the parts are lubricated properly as the force of the springs and the inertial forces are acting along the valve's axis and the face of the adjuster will slide across the valve stem.

You cannot trust everything you read on the internet, and you certainly can't bring stuff you've read about on different rocker setups and apply it to this one.
_________________
There has only ever been one man who was perfect, and they nailed Him to a cross.

[x-file]

If you've set up the rocker shaft height to get the rocker radius square to the stem at mid-lift,you've just minimised the amount of scrubbing movement of the foot across the valve tip.You can have the foot moving about 0.010" either side of valve tip centre.

It's not the end of rocker geometry (you've only fixed valve-side geometry at that stage),and there is a cure if the adjuster is not inline with the valve at mid-lift.When you get the correct length pushrod,the adjuster thread WILL be inline with the stem at mid-lift.

You then have the best of both worlds.(geometry correct on both sides of the rocker).

An elephant foot is fairly forgiving,but it's surely best if you can reduce scrubbing across the valve tip.Valve guides do wear out,and something is wearing them out.They always wear most at either end of the guide (the stem is being tipped over by side thrust).You can even see that the wear happens most inline with the rocker arm.

[mark tucker]

if your skeered of cutting pushrods&setting the geo up you might want to find somebody that can do it for you that KNOWS what there doing.or you may end up with another post/thread"my shit is afu why?" the 1.1 rocker is more sensitive than the higher raitos and will wear the guides more(just another reason to get higher raito& lower lift cam) the 1.1 rocker has a tight arc& it dosent take much to get the rocker tip going the rong way,as in outward instead of depressing the valve,that kills guides.the 1.25 isant neer as sensitive.and the foot type with the adjuster on the pushrod is less,but they all need to be right,but they can be close& still work just fine.some types better than others. I like low rocker shafts on these engines.but the 1.1 rocker can easely be too low with just lash caps or ele/swivel feet or both. the 1.1 is about the only ratio I use shims on.but each app is different...EACH ONE. and such they need to be checked&set up. the inline thing may be the way to go with 1.1 I dont knowI dont set them up that way,but it may come out like that in the end.So just getter done.

[Quokka42]

Of course you have to measure the correct pushrod length and have them cut to suit - I suspect failure to do so is one of the main causes of failures which are usually blamed on rockers. If the adjuster is in the right position during setup, it will scrub evenly either side of this equally in operation. Draw a tangent at 9 o'clock on a circle and imagine rotating it in either direction by the same amount (or better still draw these two points. Then draw vertical lines of equal length from each of these points and measure how far apart they are - magic!
_________________
There has only ever been one man who was perfect, and they nailed Him to a cross.

[modok]

Few weeks ago had a moment of clarity, a simple thing I've not heard mentioned before.

Leverage! The farther the valve tip is out of the guide, the greater the side thrust LEVERAGE! it is self evident
The farther OUT the tip is from the guide the the more the stem can bend, and side load is amplified by leverage.

Following the ancient principal of 90degree at 1/3 to 1/2 lift.........if we go with 1/3 then there is more scrub towards full lift, but taking the above into consideration..........scrub at full lift is less of a problem than near closed, so it all makes perfect sense.

A simple thing, but I hadn't really thought about it before