Block Numbers..help
I just checked my Corvette Black Book and those block numbers check out for
the engines specified. #3970010 was the block stamping on late production
350/300 and 350/350 Vettes. #3963512 was the block stamping on late
production 427/390, 427/400, 427/430 and 427/435 engines. The problem you
have is just which horsepower those blocks originally had or now have and
whether or not they are actually Corvette engines. The same basic block
casting is often used for other Chevrolet or GM products. When a Corvette
engine is assembled at an engine plant, an important number is stamped onto
the block. On the '69 Vette, it is stamped on a machined pad just forward of
the cylinder head on the passenger side. Starting in 1957. stamped engine
numbers started with an alpha character indicating build plant. Early
engines up until 1966 used "F" for Flint and "T" for Tonawanda. In 1969,
this number was "V" for the Flint plant and "T" for Tonawanda. I should
mention that all Corvette "Big Blocks" were made in Tonawanda. The next 3 or
4 digits designate the date of engine manufacture. The last 2 characters in
1969 are referred to as the "Suffix Number", even though they are alpha, not
numeric. The Suffix indicates the engine's intended useage. An example would
be F0112RF which would translate to a fuel injected engine (RF), built on
January 12th (0112) at the Flint plant (F). The Suffix number is very
important and has almost always been exclusive to Corvette useage. The
number containing the Suffix is hand stamped into the engine during assembly
by a worker using a tool containing the complete number set. There are
several possible suffixes for the cars you are looking at:
The 350/350 had the 4 following possibilities:
GC - Manual Transmission, Transistor Ignition
GD - Manual Transmission, Air Conditioning, Transistor Ignition
HW - Manual Transmission
HX - Manual Transmission, Air Conditioning
The 427/435 had the 6 following possibilities:
LP - Manual Transmission, Aluminum Heads
LR - Manual Transmission
LT - Manual Transmission, Heavy Duty Clutch
LU - Manual Transmission, Aluminum Heads, Heavy Duty Clutch
LW - Automatic Transmission, Aluminum Heads
LX - Automatic Transmission
So check the engine Suffixes carefully!!! But it doesn't end there! When a
Corvette engine is built, the engine plant knows the intended use of the
engine, but not into which vehicle it will be installed. So when the engine
is mated to a vehicle at the Corvette assembly plant, another set of
numbers containing the sequential part of the vehicle identification number
(VIN) is stamped into the engine to key it to its specific body and chassis.
This number is stamped into the same pad as the Suffix number. More than any
other single number, it is this number's match to the vehicle number that
constitutes the "matching numbers" terminology. Sadly, it is also the first
number to be forged in a counterfeit Corvette!!!
Good Luck with your decision! Hope this helps!
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