Does anyone know how much preload our lifter have?
 

I was talking to a cam grinder today. He thought he could change my base circle and get a euro cam out of the US core. Here's what he needed to know.

1) The measurement from the baseof the cam to the valve

2) And the preload of the lifter

I guess if this could be done someone would have done it already, but it's worth a look.

Erkka was talking about doing it on rennlist with S4 cams, at least of couple of threads got started.

I would think you could do it. The Chevy guy's do it all the time. I guess the lifter preload is the key. It's likely you can change the preload with the valve seat and valve.

I've been talking to cam people recently, but what I don't know is;

What the downside is, why don't we hear about people doing it on the 928?

What the limits are, and why?

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As I understand it, a "little" reduction in the base circle is possible within the tolerance of the factory hydraulic lifter. More than that and you need a "lash cap" or a valve with a longer stem.

Reducing the base circle increases the lift, but what does it do to the profile, the duration and ramp rates? Clearly its halfassed shade tree mechanic stuff. At some point in time you have to ask yourself WTF am I doing, and either get the best 2v cam you can or just switch to 4v heads.

I did it on a BMW 2002. Actually it's done all the time. The problem is we have hydraulic lifters. I'm going to follow the path over the winter and see where it brings me.