[BLACKJACK]

HI, MIKE:

THE ENGINEERING NUMBER AND THE DATE CODES ARE TWO DIFFERENT THINGS.

THE DATE CODE ESTABLISHED (VIA A CASTING NUMBER) THE DAY MONTH AND YEAR THAT A BLOCK WAS "CAST".

MY 427 S/O IS MOST LIKELY A SERVICE BLOCK BECAUSE IT HAS THE CAST-IN VERTICAL RIBS ON THE PASSENGER SIDE - FORWARD ON THE BLOCK; ALSO, BECAUSE IT HAS A DATE CODE FOR APRIL 1968.

I TOO HAVE HEARD THAT THE ADVANTAGE OF THE LATER BLOCKS WAS THAT THEY INCORPORATED EVERY IMPROVEMENT DEVELOPED THROUGHOUT THE PRODUCTION RUN. ADDITIONALLY, THE VERTICAL RIBS WERE A LATE IMPROVEMENT - NOT A COMPENSATION FOR DEFECTIVE CASTING. CORE SHIFT IS SOMETHING THAT COULD TAKE PLACE AT ANY TIME, IN ANY YEAR, ON ANY BLOCK AND IS NO MORE LIKELY TO HAVE OCCURRED ON A 1968 SERVICE BLOCK THAN ON A 1966 PRODUCTION BLOCK. BECAUSE OF THE ALREADY SPARSE WALL THICKNESS ON THE 427, CORE SHIFT BECOMES INHERENTLY MORE CRITICAL THAN WITH OTHER BLOCKS.

I HAVE A REALLY HARD TIME BELIEVING (ALTHOUGH I HAVE HEARD IT SAID BEFORE) THAT FORD MOTOR COMPANY WOULD "JURY-RIG" ENGINE BLOCKS THAT WERE DETERMINED TO BE DEFECTIVE AND THEN PASS THEM OFF INTO THE MARKETPLACE.

Y'ALL HAVE A REALLY GREAT DAY,

BLACKJACK