Imp Heads Standard V Modified

After putting a standard Imp head through the MHTools mighty mechanical saw, you can see there is room for improvement.
The ports closes right up around the valve guide, this is the same on the inlet ports also, incidentally if you have not already guesses by the carbon deposits these views are of the exhaust ports.
The sport head is a stronger casting with the water gallery's further away from the port allowing it to be opened up further with a reduced chance of cutting into them, but of course all heads vary slightly so there is still a small chance of disaster if opening them up to over 1.00"

My new race Started life as a rather grim head I got second hand, the valve seats and guides were shot and part of the combution chamber was missing exposing the wills ring. Now back from repair by Martin the the chamber wall welded up and also the water galleries done and modified, pressure tested and new valve guides and seats fitted and matched. Head was skimmed and wills rings groves re-done. Next job is balance up all the chamber volumes in the head and bed in the valves, better get on I am racing this engine in a few weeks!