Well just when I thought no one was making any new parts for the DS, I was looking on the WEB Cam Racing site http://www.webcamshafts.com/

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The 570 grind and the 590 grind, which is what I have been running for 2 years now the #590 grind is written as
Excellent torque and acceleration. Recommend higher compression piston and exhaust. Must use spring kit VC-B03 &lt;--WORKS GREAT WITH A BIG BORE

NOTE, not a Rev machine with these cams about 8400 RPM, maybe higher on a stock bore.

Meaning good for us fat boys and a 720/730 kit !!
The spring kit is their shim under bucket which is a whole other discussion.

 

dear erbe , have been reading alot of your topics latly , just ordered 590 grind , i too am trying to acheive as much torq and bottom, and as much top as that leaves. any way i was wondering the effect of matching the combustion chamber to the cylnder [big bore] to prevent detinition. i'm running 11.5.1 piston and did the ring , and i have a very smooth , strong bottom very torqy. but did other mods at the same time , don't know what did what figure you know the low down, is it worth it or not?

 

Brain if I understand the question, Matching the Head Dome with the large bore cylinder, what I recall was the porter opened up the dome some and reshaped it, every porter has there own ideal of how to do this, all I know he removed any edges that could cause Detination, apperently he did a good job, when Preacher looked over his work and gave him a thumbs up for the duner port head, so Im happy