Light
weight valves (1 ¾ Ex, 1 5/8 In), thin (1/4”) stems, thin guides therefore
less restricted inlet and exhaust tracts. Lower pressure valve springs, due to
less reciprocating weight. Lightened pushrod ends. Modified rocker geometry to
give more valve opening with the same cams (the ratio is 1.36:1). Modified
piston to give .030 squish band. Head welded up to “boat shape” to reduce
combustion chamber volume, improve shape and mate with squish. Central spark
plug. Comp ration of 9.7:1 and no head gasket or base compression plates.
Piston machined to squish and valve clearances. (This proved to be the weak point in the long run as too much material was removed and a pin hole burned through at the hottest/thinnest point. This only happened after a London to Brighton (100 mile) thrash with Dommies, Goldies, A65s and Bonnies cruising at 90MPH and flat out when possible!) Still, look on the bright side – this failure pushed me into a Phase Two build!
O rings sealing the head/barrel oil drain, to overcome a small but persistent leak.
Big solid head steady lug welded to the rocker box.
