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Signs of a true Midyear Bigblock

wavbyby

Member
Joined
Dec 5, 2003
Messages
15
Location
Florida
Corvette
63 Coupe 66 stroker 70 LS5, 72 LS5
I am looking at a '66 NOM Vette that is said to be an original 427-car. I have a correct '66 427 Corvette engine set-up looking for "the right car". I have been told that some of the indicators of a true midyear big-blocks are: Original AZ code big block rear, Rear sway bar, seven leaf springs, 80 PSI oil gauge, tachometer redline, hood support on left side. Can anyone tell me if these are correct and if there are other signs that I can look for in order to reccognize an original midyear Big-block?
Thanks
 

IH2LOSE

Well-known member
Joined
May 24, 2001
Messages
3,908
Location
We Will All Meet Again
Corvette
1966,and a 1962 thats almost complete
First let me say by no means am I an expert on vettes

I used to say original documents but,Now adays there is no real way to tell because you can get them reproduced.

The NCRS pocket book list all of the codes for a Big Blocks rear end ,The AZ code is not the only one.

Also the rear end yolks to the half shafts have bolt on caps instead of
u-straps

The fuel line where its up by the fuel pump connection is different (comes out in a different place)

If it was 425 car there would be no hole on the fire wall for a resistor.

Then there are some other hidden holes for the ti wiring harness clamps

There is some other stuff but I dont know of anything definitive that would say this is a big block car.Just about everything you ll find between a small block and a big block can be modified to make the car appear as a Big Block car.

I know this topic comes up every so often , I did a search of the archives and could not come up with anything

That being said enjoy your new car.
 
Joined
Mar 6, 2005
Messages
1,074
Location
Trois Rivieres, Quebec, Canada
Corvette
63 Resto Coupe-Red 65 Roadster
Don't loose any sleep

If you don't plan on playing the proverbial " numbers game " or want to make this Corvette a retirement investment, then what difference will it make. :ugh

If you are like the majority of owners who buy, and use them for what they were intended for, then weather or not it had an original big block becomes a moot point. Any car, Corvettes included can be set-up, forged, represented as being something they were not, and like funny money, it is usually done for profit.

If the car is decent, priced right, and something you would eventually be happy with, for God's sake, buy it , and build it exactly as you would like to have it. As I have said many times before, " He who pays the bill's chooses the build "

Rest assured that once you have completed your project, and people see you drive by, nobody will comment on such a cool ride, and then complain that you did not begin your project with an original big block car, or that it's a shame your numbers are incorrect.

The only numbers you should worry about are the cost to purchase the Corvette, and your cash outlay to complete the project, nothing else.

Good luck with your choices

Stepinwolf
 

wavbyby

Member
Joined
Dec 5, 2003
Messages
15
Location
Florida
Corvette
63 Coupe 66 stroker 70 LS5, 72 LS5
-If you don't plan on playing the proverbial " numbers game " or want to make this Corvette a retirement investment, then what difference will it make. :ugh -

I appreciate the response, Although I do not want to play the numbers game, I enjoy my '66 stroker and would not change a thing, but having restored several Corvettes, I find it much easier to go back with the original equipment that the car was intended to have. I find that GM engineers had a mechanical reason for all the different setups supporting the various drivetrains. I currently have two # C3 BB and I often see clones and can tell the difference between the real ones and the clones, regardless of them being "a numers car" or not.
 

magicv8

Well-known member
Joined
Mar 18, 2003
Messages
656
Location
Going too fast over the hill.
66big blocks used an 11" clutch with a 14" diameter 168 tooth flywheel, EXCEPT L-88 (which used a 10.4" clutch with a 12-1/2" , 153 tooth flywheel). '444' (cast at top) clutch housing designed for use with a 14" flywheel. It was used for 1966 and very early 1967 Corvette with 427 (except L-88).
Other BB-SB differences:
instruments (80# oil and possibly 5kredline tach)
steel line from high limit oil pressure gage to engine.
front springs (tagged)
front AND rear sway bar with 2 trailing arm holes drilled to mount the rear bar.
BB battery cables with riveted cable clip near RH (pass.) side of tunnel opening
BB and SB A-C cars have a LH battery holder and a washer bag
brass GM radiator, plastic shroud
no aluminum expansion tank, mount holes filled from bottom
hood with intake port(s) and LH support after 65
all engine accessories except A-C compressor and PSpump
power steering pump hose and fitting
clutch cross shaft
lower splash shields have different exhaust cut outs
2.5 inch exhausts
exhaust heat shields
.375 fuel line pointed forward for BB pump
at, au, az, fa, fb, fc code stamped on differential
tapped differential yokes with bolt on caps
BB throttle lever curves back from pivot toward rear of car, SB is straight
TI box bolted for L79 on LH wheel well and its wiring clip under the master cylinder
Registration weight shows BB added to the (327 with 3 speed) base car:
Convertible curb weight 3160
Coupe curb weight 3140
"add" weights:
a31 Power windows___ +5
co7 Hard top________+49
c48 less Heater______-20
c60 a-c____________+93
j50 power Brake_____ +12
L89 aluminum Heads__-73
m20 4speed _________-5
m35 powerglide ______+1
n40 power Steering__ +21
u69 radio __________ +21
l79 327/350 ________ -8
l36 427/390 ________+215
l68 427/400 ________+151
l71 427/435 ________+149
 
Joined
Jan 1, 2002
Messages
7,246
Location
Washington, Michigan
Corvette
'67 Marina Blue Convertible
seven leaf springs

Big-blocks used the same 9-leaf rear spring as the small-blocks; the F-41 option used the 7-leaf rear spring (along with a 15/16" front sway bar - SB was 3/4", BB without F-41 was 7/8"), and F-41 in '66 was only available with the L-72 engine.

:beer
 

wavbyby

Member
Joined
Dec 5, 2003
Messages
15
Location
Florida
Corvette
63 Coupe 66 stroker 70 LS5, 72 LS5
Thank You Gents for all the great info.
 

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