Try the restrictor......you will like it.

The first and most important reason for using the restrictor was to eliminate
the need to machine a series of grooves in the rotor housing water jackets
behind the spark plug locations. This modification is still available at
Racing Beat. We use very cold NGK plugs ($25.00) each. To the extent possible
all of the heat absorbed by the plug is transferred into the water jacket
around the plug. Less heat is left inside the chamber to be absorbed by the
incoming charge and thus reduce the power output.

A hot plug lets the tip give up extra heat to the incoming charge. High heat
range plugs are for street cars slugging around town at low revs and partial
throttle to keep them from fouling. The problem is that at sustained high
output, the damn things can boil the coolant around the plug and you won't
see any indication of this on the water temp gage. The Racing Beat fix
increases the surface area of the location to be cooled, and it works fine.

But it's another thing you would have to do to build a racing engine. Another
fix that does not require machining of any parts, is the restrictor. As the
pump experimenter has discovered, you can develop very high coolant pressure
between the impeller and the restrictor. He also noticed that even with the
restrictor in place, there was still very substantial flow. The second reason
is to slow slightly, the velocity of the coolant through the radiator. I
suspect, but cannot prove, that the closer to zero time a coolant spends in a
radiator, the closer to zero, will be the amount of heat rejected. Along
these lines, my radiator is baffled for double pass. Before I started using
the Griffin radiator, I tried a full size GM radiator. It didn't work at all
until I baffled it for triple pass. Even then, on very hot days, We were
running up to 210-220 degrees. 

So does the restrictor require a larger
radiator be used? Well, in a very round about way yes. Pressurizing the
coolant raises the temp a very small amount, its true. Only measurable with
very precise equipment, however. Radiator size may be calculated with some
accuracy. One needs know the heat rejection capability required, plus some
additional capacity for ground operations and a fudge factor for coolant (or
pressure) loss. All helpfull only if you plan to operate the equipment for
sustained periods at high power settings.

Lynn E Hanover

 
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