We designed a camshaft profile just for this size engine but it will be a option for many other engines of similar size. The lobe profile is A symmetrical which helps with the limited air volume these head achieve.
To design a camshaft, we first run simulation studies which give us some idea of the airflow required etc. We have spent a lot of time and effort getting the correlation between theory and actual, correct. This always includes flowing the complete intake system as it would run in the car.
We then take these numbers and use them to get the desired % between the Intake and Exhaust sides of the head where we want them.
These early heads don't have a lot of room for larger valves or port sizes, but as the displacements are typically smaller, we can get away with lower flow numbers.
We have a really good library of new cam lobe designs for these older air cooled engines now. From 2.5L up to 4.1L both air cooled and Turbo. The 2.9L is just one of the new designs we have.
Matched with the new cam we are using the new billet adjustable rocker arms. These have a longer pad length to allow for more cam profile to be used.
From the photo's you can see the valve train is pretty conventional. The cam housing is 4 journal unit matched to the early heads. This requires the valve lengths to be slightly different due to the cam design and the rocker arms used. Nothing difficult, just have to look at the contact patch on the engine of the valve throughout the valve motions. This sort of thing is typical when involved with any engine using custom parts.
The valve springs are OE but the pressures are a lot less than stock as our cam design allows for less forces to be used. Steel retainers are used over Titanium as I'm not a big fan of Titanium in street engines, unless the valve train is inspected regularly. Tool steel is a better choice here, but we had to make a small compromise to fit the budget. Brand new retainers or at the very least an idea of time and crack check used ones is always a good idea.
As I get into this build further I will post more photos and description of the work done. I'm really enjoying myself here as this engine is so much less complicated but it still requires attention to detail and focus.
