Circle track and stock car racers running Ford’s 347 V8 racing engine reported to the automaker that their engines would lose power after long runs at high RPM. Further testing confirmed this, so Ford engineers went back to the drawing board.
What they found was the piddle valve check ball in the cam was becoming unseated at high RPM when the engine oil was hot. They used a stronger, higher rate spring and a lighter weight ceramic check ball, which resulted in a higher RPM power range in hot operating conditions.
The upgraded ‘R302H’ piddle valve assembly was developed for racing applications, but Ford says it’s a good choice for anyone looking to build a Ford V8 crate engine themselves due to its higher durability. Check it out in the explanation below.