Hi everyone

I'm currently in the process of buying my dream car, a 1971 Vette Since there already we're some hiccups in the documentation (LS7 engine build-in according to a review paper of a oldtimer expert, I was curious, what's really in there.
I've gotten the VIN and the engine has the matching numbers, but I haven't got the right stamped Nr. from the block and now the car is put away to storage and it's 400 km to get there. It's the formers owner daugther who is selling it.

What's on there:
CPX 71 S11 ** ** (from the Block) -> **** matches with the VIN.
and 3963569, which is from what i guess the air intake, I got only the number photographed.

I'll drive over to do some paperwork and then I'd like to confirm it's one or not. Or is this already given with the CPX stamp?
Otherwise, the car is in mint condition and I'm going to buy it anyway, but that might sweeten the deal a bit, it's not bargain anyway.

If there's already a thread for this, feel free to redirect me, I've learned that after a few years, it's better to open a fresh one instead of reviving a 15 year old zombie thread.

BR from Europe
Pesché

 

Welcome to the Forum!

As you've already determined, "CPX" is the correct suffix code for a 71 LS-6 with a TurboHydro automatic trans, and "569" is one of the two intake manifolds used on 71 LS-6's. Didn't Switzerland issue an ID tag to US cars imported to Switzerland that included information like the US VIN, engine size and horse power?

Is the CPX suffix code a given, maybe, but it really would help to see what the stamp pad itself looks like. I'd say you're off to a good start though, and if everything pans out, you've made a good score.

 

I'm happy Forums still exist, didn't see one for a long time. Thanks already for your answer!

We have something like a "Fahrzeugausweis", which is indeed an ID for a car. But the metrics in it do not fit any motor. VIN is included and matches with the both engine and chassis. Engine Size is also correct with 7440 ccm, but for PS it says 202 KW, which equals 270 PS, but there's no big block with this amount of PS. The former owner made a survey by a classic car specialist, and he wrote down 465 PS, which would make it an LS-7, which was never built. The former owner died in 2017, so not possible to ask him.

I'll provide more photos as soon as the car is in my place, which might still take another two weeks. Right now, I have only a picture of the CPX code and the Rest of the VIN. Would be a great start into the Corvette universe with a LS-6

 

Hey Folks

Now, a couple of weeks later, I finally hold everything in my Hands, papers, keys, everything has been dealt with.
What's my first step for proving this is a real LS-6, the mentioned stamp pad is the one right next to the door, right?
I'll go ahead and snap a pic tomorrow during the day, I was lucky enough to rent out a garage room at our office building.

 

Stamp pad is on passenger (right) side of block in front of the cylinder head faces up. Probably need to clean it up to read it BUT DO NOT use sandpaper!

 

LQQKS like this:




LOCATED HERE :

 

Here is something that will help you out.
THE COMPLETE (ncrs.org)

 

Or anything abrasive. Thinner or paint stripper are all you should use on the stamp pad, or you could change the appearance of the pad's surface, which is as important as what's stamped on the pad.

 

Hi everyone

I couldn't get a good picture of the stamp pad and it's mostly covered with paint, but I could read CPX 71 S11 938. The CPX part was known before, according to the list from Vette5311, it would be an LS-6? Any other indicators? There's no pads or something like in the door frames.

 

I am the guy who does the LS-6 Survey for NCRS, and have done it for the past 24 years, clean the engine pad by carefully removing all the paint, then take a few quality close photos of it and post here, or PM me and I will supply you with my E-Mail and you can send to me, I also will send you the two sheet form to fill out required to be included in the NCRS survey. There are about 77 cars in the current survey, out of a total 188 built. To be included in the survey, you need "one or both" of the following: 1- A original Factory built engine with original Tonawanda engine assembly stamping & original St. Louis VIN assembly stampings (both stampings must be factory original & un-altered). 2- Original factory paperwork showing a LS-6 engine as option, (NCRS certified Tank sticker/build sheet). Thanks, Jim Wallace

 

There should be aluminum heads only on an original Corvette LS6, with a Winters snowflake casting mark over one of the exhaust ports. Part # is located under a valve cover, 3946074. Date codes are not visible as they are underneath the head. Externally the heads should have the 2-3 bolt holes in the front, the older versions do not. There are a lot more LS6 engines put in Chevelles than Corvettes but they have several differences. The carburetor should be a Holley, with a # 4803 on the front of the choke horn (4spd). The block should have a huge screw in fitting above the oil filter, like 3/4" or 1" dia. The block casting numbers are a little hard to read, between the engine and the firewall, casting # 3569512. With a date code that matches your car. The intake manifold should also be a aluminum with a Winters snowflake logo casting, and may have a casting number of 3963569, an alternate # may be possible. Here is a pic of my "clone" LS6, yours should look similar except it should have orange painted valve covers. The correct stamped code on the front engine pad is critical, along with correct casting numbers and dates, for proof of originality. Those are the easiest items to spot. There are others. My engine was built up from parts laying around, and while the casting numbers are correct, none of the dates are, and the stamp pad is blank. To prove originality you need all three. Me, I just want to drive this monster.

Pic 1: You can just see my snowflake on the front exhaust port below the valve cover lip in this pic.
Pic 2: This is the correct #4803 Holley
Pic 3: My Holley is a later over the counter one. Yours should not have the "-1" and the date code should only have 3 digits and match your car. Very rare carb since they only made 188 with the correct dates.

 

Hi everyone

Thanks Jim for the explanation, i'll see that I can do this ASAP, but might take some weeks, since we have tons of work and when I've got spare time, i'd rather driving. And since I've got no ordering paperwork, the only way would be the have those numbers.
Thanks leigh1322 for the pics, should there be time and a suitable space to tear those things apart, I'll know what to look out for. But for now, I'm rather form the same kind as you are, I'd like to drive the monster!

 

Peschae;
You do not have to take anything apart to verify what you have. It can mostly be done with a mirror on a stick and a flashlight.
As you may or may not be aware this is one of the "Holy Grail" Corvettes. The biggest engine and second most powerful engine ever put in a corvette. And one of the most rare. They built almost twice as many of the vaunted L88 race car package, and these have flown under the radar for many years, but it is actually a much more streetable engine package. It's value can be as much as three times what a normal big block is worth.

So you should proceed very carefully, like in an archealogical dig. Verification of the identifying numbers and the paperwork is what substantiates the increased valuation of an original. The more documentation, originality, and condition, the more value.
And the engine "pad" is the most important, and regularly faked. So it comes down to the letter font and the scratches or broach marks on the pad for verification. (NO sandpaper!) Q-Tips and lacquer thinner only. There are several members on here who are extremely knowledgeable and can help validate that for you, and two of them have already commented on this thread. So I am sure they will be watching. (Post #8 & 10).

Here is a copy of the information from the GM archives. There is a treasure trove of information in here for you regarding part numbers, etc. My carb is a 4 spd carb, yours is likely even more rare and should have a diifferent #, part number ending in "6", and a 4802 code #.
There were only 1,434 Corvette BBs ever produced with Aluminum heads, in 3 engine options, and this is the rarest of those:
L89 - 1,030 L88 - 212 LS6 - 188

Have fun investigating!

Please post some pics! They will help us help you.

Oh and make sure you check the front calipers and see if they have 2 retaining pins for the brake pads. You never know....