vintage Blown JAP 500cc in midjet speed car

[Richard L]

I am suggesting triggering the WI with throttle movement, it is by-far the quickest way to turn the water spray on. Knock is normally associated with high load - or lack of vacuum. using a vacuum sensor to trigger a spray is slow compared to a microswitch at the throttle plate. YPu can set the switch at 1/4 throttle etc. It is not difficult to fabrocate a bracket for a long lever micro switch by the throttle linkage.


http://www.hobbyengineering.com/H1882.html


There is a danger of spraying before you crank the engine because the vacuum switch might mistaken the "absence" of manifold vacuum as "full" load.

A good starting point is 50:50 - no other additives.