324 Camshaft Questions

[markb635]

Does anyone have any experience with the asymmetrical 324 degree camshaft that is available at Siebenrock or Motoren Israel? Specifically, it would be for use on my 89 R100RS with small valves and carbs. I am looking to gain some more upper-mid and top-end performance while maintaining a healthy midrange. A carb change and some valve and seat work are possible also.

I've read some favorable translations from some German airhead boxer sites, but I'd like some more reviews before I shell out some big bucks for the camshaft.

Thanks,

Mark

[lostboy]

It should be noted that all boxer cams since 1979 have been "asymmetric". This means that valve timing (in our case) has been advanced 6 degrees leaving the valve timing non mirror imaged, i.e. original valve timing was 10-50/50-10. The advanced timing gives us 16-54/56-4. While this was done in the interest of lower exhaust emmisions, it also gave us more torque, although it aso meant that the motor stopped pulling at about 6400 RPM instead 6000-7000.

I have installed quite a few BMW Sport Cams, which are reffered to as the 336. The 320 was installed in certain european police bikes. If the cam offered by Siebenrock ad others is actually a 324, it would neatly split the difference between a "308" and a "336", given more performance without having to rev the motor as much as a 336. I don't see how you could go wrong, but it will be expensive; along with the cam, you should also replace the lifters.

[108625]

Probably stating the obvious, but a new timing chain and valve springs would make sense too.

[markb635]

Thanks for the information guys. I planned on replacing those items along with the rod bearings so I don't have to mess again with it for a good long time.

From what I understand, the 320 cam was designed to pass Swiss emission regulations. It wasn't a performance cam.

Anybody out there that has used the 324 cam on a late small valve/carb 1000cc care to comment?