ShopTalk Forums | Aircooled VW Tech & Restoration Help

As most of you know, Roberto, Wally and quite a few others who aren't on this forum are working to get the 3 valve Apfelbeck heads with OHC for a type IV engine ready for a test run.
Wally allready made a topic for it to show the flow tests: Apfelbeck head on flowbank (pic)

Lately I've joint their team to work with them on the rocker and cam geometry. We have put some essential data into the computer to determine some shapes and sizes to get this head working. Right now we are working on the rockers, so don't mind cam timing, we will get to that point later.
As it stands we want to find out what material to use for the rocker and were wondering if some of you have some valuable input on this subject.

Here are two pictures of what we have, followed by two movies of the rockers in action.




This is only a concept, nothing is definitive yet. The idea is to make the rockers out of aluminium. We do however have limited space available so we are not sure yet if that could work. I'll run some dynamic simulations on what we have, but you can't beat experience so any input from you guys is welcome...

The movies:
Movie 1
Movie 2
(These movies are about 1.6MB in size)

Thanks in advance,

Roberto, Wally and Wesayso

That is just amazing! That would look awesome on the back of a T Shirt!

You are THE MAN!

Hello,

One word: AWESOME!!!

As for materials, have you considered to make rockers as Apfelbeck himself suggested? I mean welding or hardsoldering them from sheetmetal and tubing? I would do that, at least for prototyping and testing. The resulting rockers can then be duplicated by a CNC machine in 7075 or 6062-T6 aluminum.

Cheers,
Richard

those movies make my pants tight. simple amazing. one question in the movie it looks like a roller bearing is used for the cam. is this how it is on the actual head?

Have decided on twin or single plug?

Don't use aluminum for the rockers, use some sort of forged or CNC chromoly variant. Aluminum will work harden over time and can break. Is there any way you can move the camshaft down into the head, as this would make the head physically smaller?

Otherwise looks like a good design. You could look at the Honda SOHC head and see how the rocker arms are designed on it. They are forged aluminum (I know kills my argument) mounted very similairly to what you have as a basis. They don't have a roller though, just a wiper pad.

If you can set the rockers up so that the oil comes out of the rocker and sprays onto the vavle springs makes for longer life. Are you planning on running the cam directly in the head or are you going to go with some sort of bearing? Are these heads sand cast or some other method?

yeah come to think of it honda's thumper motors are very similar cept for another exhaust valve. like turboteener said its probably a good place to take notes.

Very nice drawings Ronald! I had seen the movies before, but not the still pictures.

Bobtail wrote:Have decided on twin or single plug?

No decision is needed: they ARE twin plugs, due to the valve locations in the head.

Our worries consist mainly the (roller) shafts where the ball rolls that follows the cam. The pressure on that shaft on too little aluminium may result in 'indents' of that (alu) area. The rocker can't be made wider in that area due to space constrains in the head. Maybe we are overly-worried tho...

The 'wiper pad' Brett mentioned may be an alternative! It might give a little more resistance, but solves the roller shaft support 'problem'.Thanks.

It would also be 'easier' for Roberto to make alu rocker as opposed to iron rockers, which would have to be molded. So the favorite way is out of alu, but only if it will be strong enough. Therefore the questions.

Ronald, maybe you could give the shaft diameter you use now and the thickness and wideness of the alu material around them?

Thanks,
Walter

I definately think that aluminum rockers are the way to go for weight as well as overall effectiveness...

The main issue is keeping the pin area strong enough so it doesn't wobble and work loose like the pauter rockers do...

Are you going to incorporate oilers in the valve covers/etc to help keep the lube where it needs to be?

roo wrote:one question in the movie it looks like a roller bearing is used for the cam. is this how it is on the actual head?

They probably will be ballbearings to support the cam that runs trough 2 heads at a time.
Something like this (not exactly but you get the picture):

These cylinders are not the ones that will be used, but I had them modelled for a different project, also the Apfelbeck
heads do have cooling fins (as seen in the flow picture) but I didn't have time to put that onto the model as it isn't needed
for examination of the rocker and cam. I do plan to put them on, just for the pictures

About the rocker size, this is what we have room for:

Meassurements in mm.
So there's not a lot of space...

wow, with such little space for material, its gona be tough!

That is off the scale guys, AWESOME!

I don't know much about material composistion...but to me it seems like an Aluminum rocker (no matter the heat treatment) has more of an expansion rate than Chrome Alloy and of course Carbon Fiber.

I would think that if you used Aluminum rockers..as they heat and expand, they would either 1) decrease lift 2) change valve geometry depending on engine temp. 3) Could lead to clearances in bearings and roller opening up or closing tight?

Like I said, I barely know my butt from a hole in the ground, but from my understanding it seems that aluminum will expand at a much greater rate than other materials of simular strength. Would it be possible to make carbon fiber rockers? some of the most demanding applications use this material, like pushrods, motorcycle frames and supersonic jets... I would think it would be possible with the right resins and material layup?

You have a lot of us Yank friends over here so if you are having trouble finding material, etc, I'm sure we all have our foot in the industry in one way or another. We can help you locate what you need. We have people of all types on this forum. Keep up the good work!!

This is one of the highlights of my day,
-Bobby

Beautiful...

Think Chromoly, ditch the roller, take a look at Schubecks rockers for Fords and Chebys, use the ceramic lifter material as wear surfaces...
(or look at Schubecks "roller tip" setup--slick)

http://www.schubeckracing.com/rockerarmframes.html

(Browse around---several useful ideas there)

I want a set of SCAT/Berg like bronze bushed rockers with the ceramic wear faces...

You would want it on BOTH ends, or an adjuster with a hardface.

Their "guided" radius and bearingless roller lifters are quite cool as well.

Seperate heads with cast in camboxes.....

How are you going to locate the heads in relation to each other?
I'm guessing that if you don't ,you may get problems with the cam binding.

Great work so far

I would ditch the roller bearings in the head. Use Phosphor bronze or other plain bearing with an oil feed.
You could possibly use the centre bearing as a coupling between the heads to keep them inline?
Otherwise you might need an external clamping arrangment.Porche used the cam bridge/support for this.
Bobcat knows this well.
kit