What’s a “V” Code?
by Greg Mross (last updated on 12/7/03)
In 1972, Oldsmobile used the 5th digit of the VIN to designate the engine used in the
vehicle. In big block Cutlass applications, there were 3 codes, “U” for big
block automatics, “V” for big block 4 speeds, and “X” for W-30’s.
The following documents what made “V” codes different from other big blocks.
Note that much of what is documented here also applies to W-30 4 speeds, but their VIN
code does not designate what transmission was used.
Lets start with the obvious. All “V” code cars came with the L-75/M-20 4 speed
combination. They also came with a 3.23 rear end (3.42 or 3.73 ratios were available only
on W-30’s). Positraction was optional.
The engine was basically the same as those found in W-30 automatics and was rated at 270
HP, 20 HP more than automatics. The camshaft was the same as the W-30 automatics, and the
Ga heads featured the larger 2.072 intake valves. There was also an oil deflector attached
to the rear main bearing. The PCV valve was mounted to a fitting in the front of the
intake manifold, not on the valve cover. Both valve covers (notched in the rear on all 455
Cutlasses) had air breathers that went to the air cleaner, like W-30’s with OAI. The
air cleaner also has a larger inlet snorkel. The engine code decal on the oil filler tube
is either UD or UE (w/ HD clutch). W-30’s are either UL or UN (w/ HD clutch). The
Quadrajet carb had an anti-dieseling solenoid.
The transmission is a Muncie wide ratio M-20 with a fine spline input shaft. Really clean
trannys should have a 1 inch high “WD” stenciled on the side. The last 8 digits
of the VIN should be stamped on the transmission where the housings split apart. These
cars originally had a complete backdrive linkage that went to the frame and then up to the
steering column. This forced the transmission to be in reverse before the key could be
removed from the ignition. This linkage was frequently removed and replaced with an
aftermarket Hurst linkage. There was also a switch on the clutch pedal that would not
allow the car to start unless the clutch pedal was depressed. The driveshaft tunnel was
cut (apparently with a torch) for the hole for the shifter. The boot retainer was made of
metal and was welded to the tunnel. Different carpeting was required with 4 speed cars and
the shift lever was different depending on whether the car had a bench seat or buckets.
Other items specific to “V” code cars include a dual snorkel air cleaner (for
cars that did not have factory OAI setups). This unit is Part # 6487337 / Code NH. (See
the Air Cleaner Page.) They also have
radiators without an oil cooler (for the automatic transmission) in one of the tanks, and
an additional metal re-enforcement bracket that was attached to the bottom of the core
support. The routing for the positive battery cable was also unique and ran along the
intake manifold and the valve cover, and used a tube that routed the cable down the back
of the cylinder head. The speedometer had no PRNDL printed on it (shared with floor shift
automatics), and the steering column had no provision for the shift lever (also shared
with floor shift automatics). Finally, it appears these cars were shipped with an engine
break-in tag attached to the turn signal lever.
I hope I have covered everything. If not, please let us know. Thanks.