There's a lot of room aft of the cam journals in the head.
It might be one chain driving a gear, which then drives the cams. That way the 2:1 crank:cam reduction can be located in the head, and the aux/balance shaft can turn at crankshaft speed.
Heck, they might even be short, single-lobe cams. With one lobe driving 2 buckets.
Poolside screwed with this post 03-28-2011 at 09:19 PM