titanium retainers should be used coated ;)
they won't give any problem with coating.

you can also use a special aluminium alloy, don't remember the name

fred ;)©

Neil,

What is the typical valve adjustment period improvement with reduced cam/rocker wear when implementing DLC?

DLC is great. F1 has been on it for years now. Great to see you’re doing that with your cams.

There should be no change in the valve adjustment period with DLC. The DLC is a friction reducer, but the rocker arm pad and cam lobe still require oil to remove the heat. Failure to do so, results in the wear and damage to the lobe and rocker pad. The lobe is typically "softer" than the rocker pad.

To answer your question further, any change in lash is always more to do with valve seat wear and valve margin wear.

Did this happen?

The answer is yes.

We have, along with many other new engine components for these air-cooled engines.

We have developed several brand-new designs and are continuing to develop both air cooled and water-cooled camshafts. We have new Valve springs to go with these new designs also having tested many of the Porsche factory springs. Some of the factory springs are very high quality and a good choice in some engine uses.

For the air-cooled engines, we have new designs that would cover engines up to 2.8L, 2.9L to 3.2L, 3.4L up to 3.6L, (our new “964 design”), 3.8L and a new camshaft design for 4.0L to 4.1L engines. These are all modern A symmetrical designs offering valve control not seen in many commonly used designs. These designs can be tweaked to suit different engine builds, with LSA’s changed for different applications.

Once the total travel from the valve seat to the piston is known during the overlap period, the valve to piston clearance can be calculated, when changing any profile or LSA without having to do any additional checks. This makes changing camshaft profiles for different applications very easy.

We have mapped cams sent to us over the years, many of them showing a quality issue that resulted in poor engine performance. Many of these are copies of copies, with many lobes different from one end of the shaft to the other.

If you expect to make a certain performance, at the very least you should be expecting the valve motions to be the same for every cylinder.

These designs will not be for everyone. Many will be satisfied with what is commonly offered. Our focus has always been on quality and as our name implies, performance development. Our camshafts only come as new billets with DLC coated lobes and journals. They are designed for those engines that require a level above and where the budget allows for a higher quality part.
To go along with these new camshafts, we are now offering a full-service support for those wanting to know what camshaft they have and should use. This includes any Flow testing that may be required. We have flowed many Intake systems in the past and have a comprehensive library of flow numbers for many of the air-cooled engines.

We will offer a mapping service of any camshaft and provide a full report of every lobe showing all the typical information including any runout and deviation. The comprehensive reports supplied will include all of the typical camshaft criteria, opening and closing events, lift, duration, centerlines per lobe, etc., etc., along with lift numbers per crank degree allowing for easier Piston to valve checks to be done in the build process.

Lobe variations, runout etc., all have huge effect on the engine’s performance. In many of these low powered engines, any differences in torque production per cylinder can have a dramatic effect on the overall performance. It starts with knowing the flow characteristics of the intake system and the control of the value train parts. If the valves are opened and closed differently per cylinder, the flow through the Intake system is compromised. It all starts with quality parts.

This information along with the engine’s component weights and use, we will supply Valve spring choices and valve spring setup information. Over springing valves is something that is often done out of fear, not based on any engineered input. Many of our designs require spring forces lower than what is typically considered, freeing up lost performance. With well-designed profiles, higher RPM limits do not necessarily require higher spring forces.

Engines cost a lot of money to build and the choice of what parts to use is a huge part of any build. Knowing exactly what part to buy can make the build result a lot more satisfying. For those that race, any additional performance gained is invaluable.

Choosing the right cam can be a difficult part of any build, with most choices been done on a referral basis. Now you can choose engineering and data into that choice.

This will not be for all as there is an expense involved, but for those building something other than a stock engine, this service will be invaluable in selecting the best cam choice for your engine. Stock builds will benefit from this service too, knowing the camshaft is of quality and it is the profile expected.

We have decided not to advertise the actual profiles, rather look at each use as a custom application. This will result in a better end result with all other engine parameters considered.

If you are interested in any of our designs, email me at neil@performancedevelopments.com.

The above post covers NA engines, but we have developed several 2V Turbo profiles as well.