Rocker Markings History

DSPTurtle · 04-13-2015, 07:34 PM

Historians of Pelican,
I have three, seemingly identical rockers, with different markings. Does anyone know what the different marking mean (None, "B", triangle)? Years, aftermarket, Porsche OE, etc.? Inquiring minds want to know!

Steve@Rennsport · 04-13-2015, 09:58 PM

Hi,

Those are the same parts, but simply from different vendors.

DSPTurtle · 04-14-2015, 05:42 AM

Thanks Steve. Yeah, I was trying to figure out which vendors used which markings. I imagine one is Mahle and one is KS but which is which would be cool to know.

Walt Fricke · 04-14-2015, 06:37 PM

At least four: triangle up, triangle down, B, and nothing. Plus some differences in form.

DSPTurtle · 04-14-2015, 08:10 PM

Great pics Walt.
Wasn't there a changeover from forged to cast at some point? I assume those would have had a particular marking also.

Walt Fricke · 04-14-2015, 08:50 PM

The forged, I believe, look different. And they were only on pretty early engines, other than for racing. In fact, the ones I know about were the racing ones, which didn't have an adjusting screw (they used different sized caps you slipped on top of the valve stem), so they look really different. Plus they didn't have a bushing. At least to start with.

But I've never had either one in my collection. Anderson has pictures, I think. Wayne too, perhaps.

DSPTurtle · 04-14-2015, 08:52 PM

I think I found a fifth version tonight. Triangle with a dot next to it. Will post a pic tomorrow.
It sure would be nice to know what all these markings mean!!!

Steve@Rennsport · 04-14-2015, 10:46 PM

I have several sets of the early, forged steel rockers and these are very different. The forged steel ones were used from '65 until '68, then replaced with the cast iron ones.

Lots of reasons, including cost of manufacture played a role in the changeover to iron.

chris_seven · 06:13 AM

Steve, I don't think they were Cast Iron which would be quite weak and have very poor fatigue life.

The majority of cast rockers are almost certainly Cast Steel and CK45 is a typical material.

They are made using an 'Investment' or 'Lost Wax' process and I think they were introduced in 1967.

The first generation of these rockers did not have any bushes and tend to gall and pick up on the rocker shafts.

The change from Forged to Cast Rockers for many cars occurred at around this time and a great deal of the driving force was concerned with the 'Second Ops'. The early Mini for example used Pressed Steel Rockers for standard cars and Forged Steel for the Cooper S. They changed to Investment castings at around the same date.

Closed Die Forged Rockers need a fairly substantial amount of fettling once they are forged and Investment Cast parts are much cleaner and easier to process and the 'raw' casting is much more repeatable than a typical drop forging.

The fatigue life of cast parts tend to be inferior when compared to forgings but if used within their design limits they do work well.

We have just re-manufactured the Adjustable forged rocker. They are made from 4340-VAR and have been superfinished after machining and nitride using a modern PVD process instead of being hard Chrome Plated.

The 'pad' length has also been increased to match the solid 906/RSR/935 style rocker and they have a original spec Glyco Bush.

nocarrier · 04-15-2015, 06:59 AM

I posted the same question.....

Can anyone id these rocker arms?

Steve@Rennsport · 04-15-2015, 08:55 AM

Hi Chris,

I've experienced quite a number of broken rocker arms over the years, but I've never had them tested and analyzed by a metallurgical lab to see what they are. The factory calls them cast iron but I really don't know.

Their steel ones never broke, but thats hard on pistons when one experiences valve float. Plus, they needed hard chrome plating to survive, hence a need for a chilled cast iron replacement. Factory iron rockers are not heat treated.

I'm VERY pleased to see that your rockers feature a longer pad; this has been a problem for a very long time in our race engines using custom cam profiles so I'm glad there are now options.

Please send me a direct e-mail with pricing information if you would.

KTL · 04-15-2015, 09:55 AM

It's surprising that for so many years the stock rocker was the only game in town, aside from the rare and expensive factory forged stockers and racing lash-cap style, and now Chris and also Pauter are both introducing their new & improved rockers!

chris_seven · 04-20-2015, 05:03 AM

Quote:

Originally Posted by Steve@Rennsport

Hi Chris,

I've experienced quite a number of broken rocker arms over the years, but I've never had them tested and analyzed by a metallurgical lab to see what they are. The factory calls them cast iron but I really don't know.

Their steel ones never broke, but thats hard on pistons when one experiences valve float. Plus, they needed hard chrome plating to survive, hence a need for a chilled cast iron replacement. Factory iron rockers are not heat treated.

Steve,

That's an interesting observation and I dropped a broken rocker onto a grinder today and was quite surprised at the 'spark pattern'.

It certainly didn't look like a CK45 steel and didn't look like a traditional Cast Iron.

The sparks were dark red, quite short and didn't break into many 'rosettes' which I would associate with relatively high Nickel contents.

It has been years since used to do spark testing on a regular basis but you never forget the basics.

I am now really intrigued and will have to have one carefully tested so we have a better answer.