I am looking at buying a 1968 Corvette Convertible 427 4 speed. It looks all original but the owner is unsure if it is or not. I have a few questions, can you please help me?

1) How do I know it is a real 427 car? I don't want it buy it if it is not an original 427 car.
2) How do I tell if the motor is the origianl 68 Corvette 427 Motor?
3) How much is one if these cars worth? Nada gives an obscure value on this car. Not sure if it is the true value or not. The car is in nice driveable condition.

Any help would be greatly appreciated.

Thank you,
Darrell

 

The numbers on the bellhousing flange, the date code on the passenger side of the middle of the block near the pan rail, and the assembly code and partial VIN on the stamp pad in front of the passenger side head are all used to determine what the engine is.

Then originality is determined with all of that and the condition of it as to whether it has been restamped to look original, or not.

Values are all over the place. NADA, KBB, and others are frequently not very accurate on these old Corvettes and for good reason - there are too many variables to judge.

If you can post some very detailed pictures of those areas, and the rest of the car, many on here can help you.

The other thing you can do is pay someone who really knows these cars to go with you to examine it for you. You can literally overpay by 100% if you make a mistake, so having someone who knows this stuff is well worth it.

Good luck.

 

above 427 ci / 435 hp




above 427 ci / 390 hp




above 327 ci / 300hp

 

Does the seller have any original factory documentation for the car? Tank sticker, window sticker, dealer invoice, etc? Do you have a Corvette friend who can take a look at the car?

Check the pad on the block at the front of the right head. The engine code and VIN derivitive will be stamped there. Jot down what you find.

Depends on the condition of the car. Post some pics. Expect five figures.

 

If you're going to pay the 'original engine' surcharge, don't even think of trying to determine a restamp from a real one all by yourself. Hire a pro.

 

Ill check those places and Ill try to post up some pics.
He's also sending me some pics of the tach.
Its a few hours away from me but I hate to pass the car up if it is an original car. I have him talked down to 10k

 

Nice, but be aware tach faces are somewhat easy to replace.

.

 

$10K for an original 68 Convertible with the 'original' 427? One helluva a deal unless the car is a basket case. Certainly, please post pictures!

BTW: A wrong tach is a big red flag. The right tach doesn't prove anything by itself, just one of many components which are unique to the big block. Best evidence would be block casting number, date code on the block, and stamp pad with partial VIN. If you're concerned about being 'original' try to get somebody knowledgeable with a good eye to look over the stamp pad.

 

Yea. That's why I come to all of you experts to give me the info I need. You guys rock

 

I am not expecting an NCRS car or anything like that but I just dont want to buy it thinking its a 427 car when its a 350 car changed over. I am swaying back and fourth between 2 different cars, this 68 or a 61. I am buying one or the other. Just want to make the right decision.

 

Hi

I don't think you get the 61 for 10 K.
Hence, buy both.
The 61 is probably around 40K, so the 10 K for the 68 don't hurt.

And for 10 K for a 68, I would never expect a NM car.
You do need somebody that knows how to check up a Vette. For 10 K, you can not even expect a good chrome bumper C3 from your brother.

Rgds. Günther

 

The seller will have plenty of lookers asking him the same thing and giving him input. If he says he doesn't know than you can be sure that he has little faith that it is original..

but your original question asks if the car is an original BB, you do not ask if it has it's original engine, you ask how to tell if it is original.. these are 2 absolute different things. what exactly are your requirements?

keep in mind that someone can replace several components of the car. Radiator, radiator support, tach, suspension parts, emission stickers, console tag, etc.. pretty cheap and make it look like an original BB car to all but the best experts.

the price gap between BB car with a NOM 427 and a small block car with a NOM 427 is not much, both are NOM and both have a BB.

set your requirements, know how to confirm the car meets your requirements before you go shopping.

 

10K for any '68 would indicative a car that needs a lot of work irrespective of BB or SB.

OP beware.

 

If it were originally a small block and was converted to a big block it would be essentially the same as an original big block though a NOM. Pretty much a matter of installing the correct tach, radiator and radiator support, hood, springs, rear stabilizer, caps on differential U-Joints, etc.. Being a NOM it has no value to people seeking 'originals' so I don't think the fact it may have begun as a small block matters that much. Any price difference depends on the quality of the upgrade. If you are looking for a true 'original', there's a lot more to check to verify it's original. In this case, since big block Vettes are often faked, even if the block appears to be correct and has serial numbers, be prepared for challenges, requests for proof it wasn't faked, documentation. Another world...

 

Without the tank sheet, there is no way you can be 100% sure it was an original 427. You can have an expert look at all the other casting, serial and part numbers and dates and give you 98% asurance one way or the other. See what the owner says about the tank sheet. Also, ask him for the history including the dealer and place it was originally purchased. If he has the original warrany book(protect-o-plate) that should also have the original dealer. I'm attaching a tank sheet if you do not know what one looks like.

 

Since nobody has yet stated the obvious, the value of an original 68 bigblock will vary a great deal depending on which of the 5 available bigblock options the car came with,

390 hp 1 qjet carb L36
400 hp tripower L68
435 hp tripower L71
435 hp with aluminum heads tripower L89
430 hp 1 holley carb L88

 

Where on the tank sheet does it reference the VIN? Unless it is still on the tank, which is still in the car....mine is. My POP is a subsequent owner type issued by the factory and does not contain codes.

Here is a fragile ORIGINAL window sticker. Notice the VIN derivative faintly stamped after the 194379S. Now we are talking 100%.

 

The reality is you can't.

1) If you have the tank sticker on the tank in the car, you can be pretty sure. But who is to say the tank sticker isn't for another car or a fake one aged and put in later on.

2) You can't. You can have a degree of certainty, but you cannot determine it 100%.

If you are lucky enough to buy from the original owner, and he has all his original paperwork, you are into high confidence.

But most cars lost their paperwork by the second or third owner. It wasn't important. What was important was how fast it was and any time slips that proved how fast it was.

Today, almost everyone says "Check the documentation" but the reality is you can buy much of the documentation on eBay and other sources.

Documentation didn't mean much in the '60s and early '70s and disappeared immediately if the car hit a used car lot. It wasn't until the restoration craze began in the late '70s that paperwork began to have value. If you have a POP, you can be pretty sure, about as sure as anyone.

This is why you need someone who really knows these cars and can only make a best guess on the originality of the engine.

You can always pay the fee for having the engine verified by Al Grenning. His photo library of stamp pads puts them to the test as each pad changed slightly over the production process and so originals fall into line with others close in sequence but fakes usually stand out as they are not really from that point in the sequence.

It is the best shot you have, but it isn't cheap.

 

Thanks for all your help guys. I'll try to get all the information I can get on the car and try to post up some pics.

 

The VIN is not on the 68-72 tank stickers. Only a job number which may or may not be tied to the consecutive unit number

For 73 and up, the format of the order copy changed from portrait to landscape and included information not found on the earlier build sheets. VINs are on these.