1.25;1 on L3 geometry issues.

[haz77]

Hi all,

Setting the sweep geometry today on my engine build, using a CB performance 1.25;1 ratio rocker kit with Ball foot adjusters mounted on DRD racing L3 heads. All parts are new.

CB provide 1x 0.8mm & 2x 1.5mm shim plates per shaft, I put them all but they weren't enough. Stuck another 0.8mm from the 2nd set & hey presto looking good, adjuster alignment is still maybe 2<3' out but the sweep & push rod look good.

Ive got the adjusters set so that the oil hole is in line with the supply galley in the arm & the rockers are set slightly to one side of the valve stem to enable / encourage rotation.

0% lift;-

50% lift;-

100% lift;-

The first issue / concern I have is that the head studs have a shoulder 5.8mm high to locate the rocker stand blocks but Im now 4.6mm high leaving just 1.2mm of location.

Emailed CB & they tell me they would expect 2.3<3.15mm of lift to be required and that they often turn some of the threads down to the size of the shoulder and not install the stud so deep when building engines. however they also say that 4.6mm seems like allot of spacing.

So if this is the answer can I not buy longer studs with a longer shoulder & would it be ok to use a combo of 4 shims under each stand like this or should I look at getting some machined in one piece?

Secondly, does the sweep look ok or do you think I should be using lash caps, which would of course increase the required lift further, Im not 100% happy with the lash/sweep being quite so far forwards but ive never done any of this before!

I dont have a reply from DRD as yet.

[MURZI]

You need to put an adjustable pushrod in there and measure. Looks like you are using stock aluminum pushrods....... You will take the shims out in the end and shorten the pushrod length..
_________________
62 vert
2276
Tim’s welded heads
45 Dells
A1 sidewinder
Fk44 cam

[haz77]

The rod has been cut & tapped then had a threaded section added to be adjustable.

I shimmed the rocker, adjusted the rod up to the cup with the valve closed then turned the motor until the valve is at 50% lift to check the geometry's, did this with various shims amounts until all the geometry's where good.

0<100% lift is 0.475"

Running a W100, stock crank & rods, 90.5 P&C's, 8.2;1 compression, 55cc head chambers.

Shortening the rod to drop the rocker shaft will mean loosing my adjuster / valve angle alignment.

[MURZI]

What I would do is start with about a .030-040 shim. Leave your adjusters where they are. Adjust valve lash with the adjustable pushrod to .004". Cycle it through and measure full lift. Take half of that and now check geometry. It should move that rocker down towards the middle of the valve stem.

Typically anything over 450 lift I like to use the rockers with adjusters on the pushrod side. I never use those style adjusters with the balls. Have had a couple seize and fail.
_________________
62 vert
2276
Tim’s welded heads
45 Dells
A1 sidewinder
Fk44 cam

[modok]

The valve end of things looks to be perfect in the pics.

The pushrod side at 50% lift appears to be a little past 90degrees, and that means you could extend the adjuster out farther. Take a look at the pushrod side of things yourself and see if that is true, or just how it looks to me.
That would be good news as then the oil passage would actually line up!

All of the parts there are different than VW, and are a little different, so it's not unusual that you combine them all and requires some odd shims.
Wild guess.... I'd think extend the adjuster out a bit and try 3mm worth of shims. Moderation in all things, especially shims!

[haz77]

Thanks for the reply's,

I agree the rod is actually still slightly off being 90' to the cup which means either it needs to extend more, lifting the rocker even higher, or the rocker needs to drop and the adjuster needs to be wound up / out a little.

Ive set the adjusters with the oil hole / undercut in line with the rocker galley but I guess if I go up 1mm or so then I will only ever adjust down to allow for wear so if anything it will get better alignment as time goes on?

here's a photo shop close up with a rectangle layered onto the photo to compare;

Will have a go at this tomorrow.

[modok]

The edge of the rocker cup is not machined at exactly the center of the pivot and 90 degrees to the shaft. Or is it?? I have no idea.

[Quokka42]

Your problem is you are trying to set it up with the adjuster too low. Grind the bottom of the rocker level with the support that runs to the center, set the adjuster about two threads out from this, and you'll find you'll end up with about 60 thou of shim, a shorter pushrod than currently, and pretty good geometry. Don't worry too much about the centre line of contact with the valve, you have plenty of leeway with these adjusters.
_________________
There has only ever been one man who was perfect, and they nailed Him to a cross.

[haz77]

[haz77]

[haz77]

had another look at this,

Checked my lift again, confirmed it at 0.475<0.478", the cam spec card says 420 so x 1.25 (rockers) = 525, im only getting 478" max, is this how it works & if so what's wrong, 478 is only 1.13;1??

I dropped the shaft by 0.8mm & backed off the adjuster slightly and its looking ok, lucky this happened really as went to remove the head studs & not thread locked in, going to open up the shims by 0.5mm so they clear the thread then I can stand then higher giving me more block location & better thread penetration through the nut.

Interesting to note that the push rod is angled away from the fly wheel as well as up towards the top of the engine so its never square to the cup in both axis at any point, even if its square to the cup when viewed in line with the crank if you then look at 90' to the crank its no where near square anyway, in fact its not possible for it to be square to the cup when viewed at 90' to the crank at any point in the lift due to the offset angles of the assembly.

Leaves me wondering why did Vw design the push rods to run at these angles, I can understand the need for the horizontal angle caused by the position of the cam below the crank but why are the lifters & rods not in-line with the rockers / piston stroke??

[[email protected]]

.420 is at the valve with 1.1 rockers, or .382" at the cam and lifter.

.382*1.25 = .477" at the valve with 1.25s.
.382*1.1 = .420" at the valve with 1.1s.
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[modok]

The pushrods are angled so the engine can share 4 cam lobes, and the cam lobes are positioned to clear the connecting rods.
They "fixed" it with the type-4....but it turns out it didn't need fixing, as the type-4 does no better.
brilliant design, but it is odd.

Cam lift times rocker ratio =valve lift. Check cam lift by using indicator on end of the pushrod. you would already know this if you degreed the cam

[MURZI]

As you remove shims, the rocker swipe will move down on the valve stem face. Jack it up, like you have it and it will move up.

.030-.060 is where you should be. And it is very rare that a 1.25 will spec at 1.25, normally they come on at 1.33-1.35.

You are worried about that oil hole too much. I usually grind the tips of the rocker about .030-.040, run the adjuster out 1.5 turns, add a .060 shim, set valve lash with a adjustable pushrod. Now check geometry, do I have to go up or down? Add or remove shims, adjust pushrod. Done.
_________________
62 vert
2276
Tim’s welded heads
45 Dells
A1 sidewinder
Fk44 cam

[haz77]

[Quokka42]

You don't need it 100% aligned, it is just another way to get oil to the ball. Everything gets pretty well oiled by splash in these setups. The geometry with 3mm was crap - you always move the middle of the "swipe" up the valve a little with 1.25s as they use the stock shaft position.
_________________
There has only ever been one man who was perfect, and they nailed Him to a cross.

[haz77]

[mark tucker]

be aware that stock type pushrod will not support much more than stock lift. the end is only half a ball it needs to be 3/4 ballend type. or ir can /will bind in the rocker arm cup. the cb rockers are much better in the cup aera than any other Ive seen. but they can still bind. also your adjuster is out quite far. if needed you can use a dremol tool to add a small slot to the thread in the rocker so it receves good oiling.Ive never seen a set where they were all in the same spot aso every one may not need a slot or some may need 3 threads sloted. be sure to clean throughly with a good oil remover & blow out with compressed air and wear some eye protection so nutten get's in your eyeballs. with the adjusters screwed in farther you can then lower the rocker assy.probably no shims at all.or just a .015 or .030 shim( I cant remember witch for the last set of cb 1.25's I installed. but too much isant good. I set the geo with the adjuster about 1/2 turn out(no more than that for my stuff) from fully seated. you may have to mover some rockers around if there machining is off a bit, but the cb's are very good. and yes you need the oil to get to the ball. they will NOT LAST with out it. they will NOT SURVIVE with just splash oiling.

[haz77]

Thanks for the reply Mark,

Ive not done anything like this before & with out this help would be stuffed, or rather the engine would

Ive got Cro Moly push rods with the 3/4 ball ends you refer to.

with 3mm / 0.118" shim this is where im at (No3 exhaust valve) on 50% lift, it doesnt look it but the adjuster is about 1/2 turn out of the head;-

I would definitely need to grind down the bottom of the adjuster head to take out any more shim, TBH not that keen on the Idea but appreciate the reasoning.

So your saying to grind a slot in the internal threads of the rocker adjuster head to extend the oil gallery up, giving more flow to the adjuster in this raised position?

[[email protected]]

Note: All these comments are regarding VW style rockers, with the adjuster on the valve end. The other style is another more complicated topic.

Those rockers need to be back cut, and have not yet had that done. Trying to move forward before that is completed is a waste of time. You have to do this to make room for the elephants foot/courier head.

The other error that is all too common is people thinking the length of the push rod changes the geometry. It does NOT. The geometry of the rocker depends on the total lift and the head/valves. After that geometry is set, THEN you tackle the PR length. It's not the other way around. Rookies are always trying to adjust the rockers to fit the push rods, which is bass ackwards. Cart before the horse. MISTAKE.

For example, the shimmage/cutting on a set of rockers and head, are DIFFERENT if you are lifting .350" compared to .450", or compared to .500". The angles of the rocker need to change so that it's "correct" at 1/2 lift. Here's 1/2 lift

.175"
.225"
.250".

And note how different 1/2 lift is with all 3 examples I just gave. 1/2 lift is up to .075" different. If the valve is open more, it changes the angle. So in one situation the adjuster is inline with the valve, and in another it's not. Same parts, different cam.

Sometimes you'll have to shim the rockers stands, other times you'll have to CUT the rocker blocks (anti-shimming or negative shimming, think of it that way). Other times it will be OK as-is.
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