My car is a 1971 454 4spd coupe. It's not numbers matching. Is there anything I can look at on the car to identify it as an original big block 4spd car?

Thanks

 

No. Factory big block cars had certain items installed which small block cars usually did not get, but since any of these items were part of an options package, any and all of them could have been installed by a previous owner.

Nothing in the 71 VIN identifies the original engine.

Do you have any original GM paperwork with the car?

Have you checked for the tank sticker?

 

Easy Mike, I have not checked for the tank sticker. Where exactly would it be if still on the car. The only thing I know about the car is the previous owner purchased it 5 years ago from a Corvette dealer in Arizona and I tried to contact the dealer but is no longer in business.

 

Top left corner of the fuel tank. These pics have been posted here:


The one above is a teaser; it is still there and legibile.

This is more common:


I do not advocate going to all the trouble of dropping the tank just to see if something may or may not be there. Get a good flashlight and try peering around the fuel collar. You might be able to see enough to determine whether something might still be there.

 

All though an easily changed part, what does it say on the shift console?

 

Don't think I will pull the tank just to be disappointed on what I find.

The plate on the console says 425hp 475tq and the air cleaner says 425hp but stickers and plates are cheap to replace. I know the current engine is a 454 truck block with 353049 heads, looks like stock intake and exhaust manifolds and a quadrajet.

 

A welded in transmission cross member will tell you if it is a factory 4 speed car. Automatic cars got bolt in members.

 

425!!?? Original LS6 car? That would be something.

 

I thought there was a difference in the tachometer redline between big blocks and small blocks. I did a quick check and found the BB may redline at 5600 and the small blocks at 6500.

Tachometers are also easy to change out so this may not be a good indicator, but its another item to check.

kdf

 

I would look for that tank sticker asap...

 

I would eventually look, but it would not necessarily be right away.

 

does the console tag look old, like 41 years old? I seriously doubt it is a 1 of 188 LS6 car..

an original 4 speed car has welded tranny crossmember both SB and BB cars

certain codes on the emission sticker behind the master cylinder probably unreadable after 41 years

certain codes on the tank sheet on the tank, probably unreadable after 41 years if it exists at all

5600 red line tach... ( 6500 if LS6 )

big block/LT1 hood

rear stabilizer bar

thicker front stabilizer bar

caps instead of straps on the half shaft u-joints..

27.5 inch copper radiator/support.

several other characteristics related to the engine and emissions, but you already said it was NOM.

as said above, any or all can be bought and installed in the aftermarket.

the hardest to fake is the tach redline ( hard to find a rare working 5600 red line, then install it.. and the radiator/support.. major effort.

failure of any of the points above would result in me losing faith that it is an original BB car.

even though you may trust the previous owner, who knows what was done 6 owners ago.

 

Pretty sure it is not an LS6. The guy I bought it from, he bought it from CnV Corvette Sales in Arizona and was advertised as an LS5 not an LS6. You would think that they would know what they were selling and it sold for an LS5 price.

Looked at a few things
It has a BB hood
5600 rpm redline and tack works
sticker behind brake cylinder says 454 but sticker looks like a repro
console tag looks as old as the rest of the interior
I think no rear sway bar
half shafts have bolt on straps to hold bearing caps and has a retainer clip

 

It may be interesting to know if the car was configured with the LS5 or LS6 option package when it left St Louis but without the original block doesn't mean much so far as value goes. The tach sounds right, 5600 redline? Sounds like somebody may have changed out parts in the rear if the sway bar is missing.. Did you confirm the UJoints are fastened to the rear end with caps?

I suspect many LS5s and maybe some LS6s met this fate years ago.

 

Joewill, Man,if I ever have this question come up, you're going to be my go to guy!!!!

 

I have a different opinion...

very high faith type of proof that a car left the factory as a LS6 ( lots of DOC), but without its original engine, would be very valuable. I would easilly pay 25K extra for a POP or tank sheet and other validating doc that said LS6, or L88 , ZR1, or L89.. if the doc was valid. people don't realize what pedigree proof does to the value of the car..

that is one extreme, now LS5 is another.. not so much difference, but if the doc is valid, there is a difference.

a documented LS5 car, is worth more than a documented base engine car, if both are NOM.. especially a convertible with A/C.

many of you won't do it and won't play the numbers game.. but many others will.

 

Whether numbers are important or not is up to the buyer. Generally speaking, I see the premium paid for matching numbers to be paying for a car which was probably well taken care of, still has its original engine. This would be especially important if the car is being marketted as all original, a survivor. In this case documentation is used as evidence the matching numbers engine is genuine. I'm not so sure a documented NOM is quite the same unless we're talking about an L88 or maybe an LS6. The engine is no longer orignal, in the eyes of some collectors this car has been molested? Having documentation for a NOM car may be valuable when establishing the NOM is NOT a clone, an upgrade. This may be valuable to some buyers though it's still a NOM. How much more a buyer would pay for a NOM which is not an upgrade vs a NOM which is a 'correct' clone? If the POP or original invoice are available, items which were often routinely tossed after a few owners, that may suggest some caring owners in the past?

 

UJoints are fastened to the rear end with caps? Does anybody have a picture of this for an LS6 and an LS5 so I see what I have.

Thanks

 

It is not necessary to pull the tank immediately. You could start by removing the rubber boot from the gas filler neck and looking around with the flashlight. If you see build sheet, then it takes some patience and manipulation with a set of tools to remove it. I took off build sheets from my 1968 and 1973 exactly this way.

 

For small blocks I think you would have ubolts like these...

http://www.parts123.com/parts123/yb....Z5Z5Z50000050G

Big blocks have caps which look something like these...

http://www.parts123.com/parts123/yb....Z5Z5Z50000050G

Hope this helps..