jeff@qubix.UUCP (Jeff Buchanan) (05/23/84)
In your request for "authenticity" info reguarding a 1971 Chevelle
you didn't say what it is you are trying to verify about the car. The
Dec. 1983 issue of Popular Hot Rodding has the article you need to see.
It gives a history of the Chevelle (p.71 & 89).
For a 1971 model, the VIN (vehical ID number) is on the upper
left side of the dashboard. The only useful info is the year and engine
codes, in fact the only engine info is # of cylinders which is obvious by
looking under the hood. Anyway, the year is called out as follows:
xxx71xxxxxxxx <---VIN
^
YEAR_______________|
There are ways of determining which engine is in the car besides
looking at numbers stamped on the block. There is a pad on the right side
of the block on the deck surface just in front of the head which is visible
without disasssembling anything. If there is a short (3-6 digits) number
with a "T" in it, then it is a replacement block. The easiest way to
distinquish between a big block and small block is the spacing between the
exhaust manifold tubes (headers) is equal on the rat motors, but the center
tubes are close together on a small block compared to the end tubes.
Externally the rat motors all look the same, but you can tell
a 454 from the others (396-427) with out a tear down. Reach down between
the harmonic balancer and the block and try to feel the back inside of
the balancer. If you feel some extra material the motor is a 454.
It is kind of like a lip about 3/8" thick which extends about 120 degrees.
This means you must be able to feel all around the back side of the balancer
near the center so you'll know if what you are feeling is the lip or not.
Actually, the lip is about mid way between the center and outside circum-
ference of the balancer, attached to the rubber part of the balancer.
In other words, if there is a discontinuity of about 3/8", then it's a
454. [The extra material was for balancing purposes. The 454 long
stroke required extra external balancing. The short (3.76) stroke 396/427
was balanced all on the counter weights]
There were three big blocks offered in 1971. A low performance
402 CID 300 hp, a low perf 454/ 365hp, and a hi perf 454/ 425hp.
The 425 hp was the LS-6 only with open chambered heads and 9-1 compression.
All hi perf engines have four bolt mains and can be identified by an
extra tapped hole just above the oil filter boss. So if the area right
above the oil filter boss has no plug or fitting, then it is a low
performance two bolt main block. This can be detemined without disassembly.
Keep in mind that since you are buying a used car, it can have ANY motor
or combination of parts different from what the factory offered that year.
The head type can be determined easily just by pulling a valve
cover. Hi performance heads, characterized by rectangular intake ports
and 2.19" intake valves, have the letters "HI PERF" cast in the upper center
of the head underneath the valve cover, clearly visible with valve cover
removed. In the same place the low performance heads have "PASS" cast.
The low perf heads have small oval intake ports and 2.06" intakes.
You can't, however, tell open chambered from close chambered
by pulling a valve cover. You must pull the head and look at the com-
bustion chambers.
There is obviously much more information on Chevelles. You can
contact me through the net anytime.
Newsgroups: net.auto
--
Jeff Buchanan @ QUBIX Graphic Systems, Inc., Saratoga, CA.
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