[Fot] radiator preasure

[Mark Wheatley]

I have a problem with pressure in the radiator forcing coolant (water) to
the overflow catch can but not allowing the coolant back in the radiator. 

I
am no mechanic, do not build or assemble the engine but would like to
understand possible contributing circumstances and possible solutions.

The
engine is TR-4, have run the same head and same bottom end for five race
weekends with none of these symptoms. changed engine builders, freshened the
bottom,did valve job with new valves same dimension, same supplier. Dyno
tested and tuned with no sign of a problem. I have used a 7lb cap forever,
have more than adequate radiator that was new 4 race weekends ago.

first race
weekend problem showed up. I'm a slow learner so I limped along by keeping the
radiator full. apparently by the time I realized the magnitude I over heated
the engine enough to damaged pistons and liners. By the end of the weekend
decided it was the radiator cap.

Bought new cap, had the pistons and liners
replaced, next weekend same problem I loose between 8 and 16oz depending how
hard I drive. Tried a 13lb cap at the track with no improvement. I located a
20 lb cap but got a recommendation to not use one that high so I did not test
that. There is no sign of water in the combustion chamber.

My questions are
what can cause this change and what might be my solutions.

thanks in
advance,  Mark Wheatley
                             #86 TR-4










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