I have a uncle that has a 65 coupe that he has had since around 1970,the car has sat untouched since about 1980 and I am trying to pry it away from him,but here is the question.he thinks that car was a big block car when it was bought new but the first owner changed it to a 350 for some reason? the car curently has a 350 that was a gm replacement bought by my uncle after he had it a few yrs.He says he had the tank down and couldnt find the build sheet/sticker or whatever you want to call it.I wanted to know if there is a easy way to tell if it was a BB car or not.only thing I know is that it has a battery mount on the drivers side but also has one on the passenger side but it does look like a aftermarket one.

thanks in advance
Jared

 

My 67 is probably an original BB car that is now a small block. The battery is on the left (driver's) side, though it is an air car, so it would be there anyway. A BB or air car will have a factory installed cover plate in the wheelwell to remove the battery.The hood prop was originally on the left side as well, though it is now on the right. The car has the rear end with the bolted caps on the U-joints, vs the stamped steel clamps. Also a 7 leaf HD rear spring and a rear sway bar. Front sway bar is also larger that a SB car, but I don't remember the dimension. I'm not sure all this applies to a 65, but I think most of it does. It wasn't too uncommon for SB's to end up in BB cars, 'cause there was a time in the 70's that you couldn't give away a BB. Same with convertibles. At one time, they were the poor relation of the coupes.

 

'65 was the first year that any BB was available on a corvette and it wasn't until the 2nd half of the year. I'm not sure if there is any way to tell if your car was originally a true BB car with the 396 motor in it but one way to check to see if it was at all possible is by the VIN number. Availability of the 396 began approx. with VIN # 13,000. If this '65 has a VIN below 13,000 it couldn't have been a 396 BB car. If the VIN is above 13,000 it could be possible but I'm I don't know how to tell you to determine that positively without the original window sticker.
The true 396 cars are relatively rare as they only made 2157 of them out of a total production in '65 of 23,562 cars (8186 coupes).
You wouldn't have found any build sheet on the gas tank as they didn't start doing that until '67.

The battery trays on the BB cars were on the left hand side and the original battery trays had corners that were cut off in a triangular manner where reproductions or aftermarket units have a radius corner.
the hood support on '65 BB cars was on the same side as the SB cars (right-side) so no clue there.
If the original fan blade is still in the car the BB fan blade assembly number is 3872792
if the original radiator is still in the car, the proper BB radiator was a Harrison aluminum radiator painted glass black and they used two designs for the BB cars. check for part #'s 3005936 or after VIN # 16,200 look at part # 3007436.
The BB cars had a .875 (7/8") front stabilizer bar rather than the 3/4" bar on a SB.
The BB cars had a 9/16" rear stabilizer bar
BB cars had a tach with a 6500 redline (same as SB 365hp and 375hp SB cars).

 

A few more clues to a 65 BB in addition to what has already been mentioned...

1) 80 lb oil pressure guage (instead of 60)

2) Big block hood (pretty obvious but thought I would mention)

3) HD caps on U-joints vs. the lighter-duty straps of the small blocks.

4) Larger diameter fuel line from tank to engine compartment

5) Transistor Ignition

6) my hood support is on the driver's side which I believe to be correct.

According to most "experts" the big block appeared in mid March of 1965. That would put the VIN sequence (last 5 digits of the VIN) at about 12459 for the first BB car. The earliest VIN I have seen with a original BB is 12806 if memory serves me.

 

Biggus

that is also helpful but:

1. the L76 and the L79 SB's also had 80lb oil pressure gauges.

5. if the engine was swapped out they most likely also swapped out the entire ignition system with it so hard to determine anything from that. also, the TI was available as an option on the SB's.

6. not sure what is correct on the hood support. I had also thought the proper side on a BB car was on the left side but according to the '65 NCRS judging book it list both the SB and the BB as being on the right side - unless it's a misprint in the NCRS book.

The larger fuel lines and the caps U-joints on the BB cars are both good clues as unless it the prior owner went to extreme lengths to "hide" the fact it use to be a BB car most likely those clues are still there

 

SB and BB used the same size (3/8") main fuel line - they were bent differently at the front where the rubber hose goes to the fuel pump; the BB bend is nearly 90*, and the SB is more like 20*.