I used to build the car for what was a very fast driver on the east
coast, it was able to run with Mike Jackson and Jeff Snook. We used Carrillo
rods and Wieseco pistons. We managed to break a Carrillo rod into 5 pieces!
It turned out to be the pistons fault as it was experiencing "four Corner
seizure" according to the experts at Wieseco. They had designed and produced
the pistons and had not put enough cam profile into the skirt. It would
expand when hot and create a hell of a lot of friction causing the bearing
to fail and allowing the piston to hit the head. At 7,000 rpm, it did not
take long to come apart. The piston clearances measured fine when cold with
sufficient wall to skirt clearance, the Wiesco experts gave us the clearance
figures and the pistons were right on the money. They just expanded too much
on the corners when hot. As a side note, I called Carrillo and asked how
much their rods stretched in use as we thought we did not have enough deck
clearance and that the piston hitting the head caused the rod to fail. Their
answer was 0.000, the do not stretch. But, they said to remember that you
have about .0015" rod bearing clearance, the wrist pin will deflect about
.0005", there is .0005" clearance in both the rod and piston for the pin.
All told, they said to estimate about .0025" to .003" total elongation in
these items plus add in crank flex and a tad of rod bolt stretch and you can
have a total of .005". If you are running a very tight deck height, this can
cause a piston to kiss the head and ruin a rod bearing. Barry
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