Now im clear about all this breather pipe stuff! I think the manifold leak was causing the rough running, and the idle speeding is due to the butterfly, but its running pretty sweet now.
The power is really improved, loads of torque in the low end like i was hoping for. I drove the car a little after changing the head, and it wasn't a lot quicker, the 1.5" carb,manifold etc really boosts it.
Looking at the butterfly, i don't think it ever had a valve on it, so why would someone drill a hole in it? for racing perhaps?
anyway, thanks again. Looks like the exhaust seat machining did the trick too.... i hope
