decoding a car

[Guest fast eddie1970]

any way to tell what motor came in a car without build sheet?I talked to the guy i got my 70 from and when he bought it in 1979 he was told at the dealer he got it used at the car was a 402 4 speed car !but it hade a 327 4 speed at that time .

[Sam (Bones)]

if you have the protecto-plate

[overdrive]

I've read that the big block cars had round rear, lower control arm bushings and the small block cars had an oval one there. Each time I've checked this out, it has held true. Lyle Groves told me that he wasn't sure this is always the case. He may very well be right. The members here may be able to shed some more light on this.

 

Lyle also told me that the big block cars have a bolt on the steering shaft, near the rag joint, that the small block equipped cars didn't have.

[Sam (Bones)]

there are always a few cars that are put together out of the "norm" the steering shaft is usually a good indicator of whether it's a big/small block car, I wouldn't rely on the control arm bushings, but still...these still don't guaranty it was a big block car

 

what rear axle does it have???

my '70 4 speed came with a 350/300hp, 3.31, 12 bolt posi, if it's a 10 bolt, I doubt it was a big block car, BUT!!! many small block cars got 12 bolts too!!!!

[RichG]

Supposedly, (according to the GM restoration package) the 350 2bbl cars got 10 bolt only, and 350 4 bbl and up got 12 bolts. The 3 speed manual trans was only offered with the 2 bbl motor. The 4 speed was for 350 4 bbl cars and up except for the SS454. I've also heard about the control arm bushings but can't find anything in the parts books that says one way or the other.

[Guest fast eddie1970]

I read that bb cars had dual fuel lines but that was on a 71 didn't know if that held true mine was a 12 bolt car but it was lost to the racing cause along with the trans.What do you mean about the steering shaft bolting on?

[monte70car]

My Monte started out as a turbo fire 400(small block) with a 350 trans and 2.73 single track rear end. Interior wise it was a bench seat car auto on the column and stereo speakers. Exterior wise it was a code 50 car with a gold top and gold interior. When I got the car someone put a 65-65 396 down in it so there was no need to try and keep it stock.

[NateZ]

Off the top of my head, and I'm a bit rusty, you might be able to tell if it had a BB by looking at the redline on the tach (assuming you have one and assuming the tach is original). Anyway, most of my knowledge is on Chevelles, but I can tell you that it is generally agreed that:

 

1. The 307 and two 350 engines tachometers redline at 5000 RPM.

2. The base 396 (L34 402BB), the LS3 402 (402 big block with 4bbl in Monte Carlos), and 454 engines tachometers redline at 5500 RPM ** (see exception).

3. The high performance 396 (L78) and 454 (LS6) redline at 6000 RPM.

 

On #2 above, the L34 is actually a 402, usually referred to as a "400" or "400-4." Chevelle Super Sports were still called SS396 cars because Chevy figured why change the name when customers have been used to seeing "396" on SS Chevelles since the mid-60's? The odd motor out is the LF6 (400 small block with 2bbl). I don't have info on the redlines for these cars. Sounds like you think your car might have come with a 402 BB.

 

** The exception is Atlanta-built cars because to date, all documentation shows that the Atlanta plant installed the 5000 RPM redline tach in all base SS454 (LS-5) Chevelles, so I assume this also applies to Monte Carlos which also had the LS-5. It is assumed this was a computer programming error that generated the code for the 5000 RPM tachometer instead of the 5500 RPM unit. Kind of a moot point to bring this up since you don't have an SS454, but I wanted to put this out for anyone else reading this, and because a 402 BB car might also be part of the exception.

 

ALSO, I'm not 100% sure about this, but I've been told before that the size of the fuel lines might be an indicator. It appears that many of the 4-bbl cars came with a 3/8" fuel line (possibly with a 1/4" return line), while 2-bbl cars tend to have a 5/16" fuel line. Anybody confirm?

 

~ Z

[Guest fast eddie1970]

No tach on mine 3/8 single fuel line,also lower control arm rear bushing is oval and on the rear suspension it has factory bars from upper to lower control arm

[monte70car]

I believe all cars had the trailing arm support bars running from the upper arms to the lower. This was so the rear end wouldn't twist. And Nate your information on the tach hold true to the Monte's- the ls6 tach.

[Guest fast eddie1970]

My car also only came with a 3 bolt rad cover i would think bb would have a heavy duty cooling system?

[CrazyDavey]

My car also only came with a 3 bolt rad cover i would think bb would have a heavy duty cooling system?

 

yes, and a 4 bolt cover....Dave

[monte70car]

Maybe that's why my came with the 4 bolt cover plus it had a/c and a 400 small block.

[Sam (Bones)]

mine came with a three bolt cover, and a small radiator, the motor is a 350/300 4 bbl, the opening in the core support is smaller too, and it has the round bushings, and a 12 bolt axle