I'm currently looking for an early C3 to purchase for myself. There is a 1971 Coupe that I am considering. It is a beautiful car. It is advertised as a numbers matching 350/270hp engine with the original 4sp transmission.

The engine stamping ends in CJK indicating the car should be equipped with a 350/270hp engine and an automatic transmission. The VIN matches the car.

The owner claims that the 4sp transmission and engine is original to the car.

He is going to try to locate the VIN on the transmission.

There are no documents that show what the car was originally equipped with.

Clearly there is a discrepancy.

How common was it to swap the autos with a 4sp?

How common was it to replace the engine and re-stamp it, and accidentally stamp the wrong code?

Could it have been a factory error?

Is there anything on the car that only automatics had that I can look for?

The car is a few hours away. I'm trying to figure out if it's worth taking the trip to look at it or not. I wont be interested in the car if the engine or transmission is wrong for the car unless it were priced accordingly.

Thanks for the help!

 

The transmission should be stamped with the same VIN derivative as the engine and date coded. Is the date pre or post vehicle build date?
The transmission cross member for an automatic was bolted in, the cross member for a manual was welded in.

 

Hi Nate,
Seeing the stamps on the transmission case will pretty well tell the tale.
They'll indicate when it was assembled and what car it went into in St.Louis.
Also, get a picture of the transmission crossmember….4-speed was welded in and automatic was bolted in.
Good Luck!
Regards,
Alan

Hi R, I was reading your mind while I was typing!!!!

 

Short read!

 

Hi R,
My 'access code' only allows me to read a small part of it!!!!!
The good stuff is all heavily encrypted!
Regards,
Alan

 

Not only was it very common, it still is. Do a search of the Forum, and you'll find plenty of recent posts about doing the swap.

I don't think that's to common. I won't say it's not possible, but most people who go to the trouble to restamp a block, make sure they're stamping the right suffix code.

It's possible, but very unlikely. Normally, blocks that were stamped wrong got caught, and were corrected. These corrected stampings are well documented, and are known as grind outs.

Besides the bolt in crossmember, mentioned by both Alan and Revi, the floor of automatic cars, is different too.

To install the Turbo 400 in 68-77 Corvettes, Chevrolet had to modify the floor pan. A bump out was installed in the right side floor, where the floor/tunnel/firewall all meet. The modification isn't real noticeable, with the carpet installed, but if you know what you're looking for, you can tell the difference in the floors by feeling around in that area of the carpet. The bump out can be seen fairly well from underneath, again if you know what your looking for. Checking the floor is the best way to identify an automatic car, as most people won't go to the trouble to change it.

Automatic cars will also have a hole in the trans tunnel, forward of the larger hole for the shifter. This is where the auto shift cable came through, and I don't believe it's present in 4 speed cars. Of course, you need to have the console out to see it.

You can check to see if the back-up lamps work, or if the switch is in place on the trans. Often, people seem to leave it off, or fail to reconnect it, when they do the auto to 4 speed swap.

 

Thanks for the info about the cross-member and the floor. I will ask him to look for the cross-member, that will be the easiest method.

If it turns out to be an automatic car, that will be too bad, I'd have to pass on it. It just wouldn't settle right with me, even if it was converted as good as factory.

 

under my '72 showing the patch that's installed in the tunnel on passengers side.

 

Based on the seller's story so far, can you trust the response?

 

Owner has sent me a picture of the cross-member, it is welded, I am very confused at this point.

 

welded=orig 4 spd

 

Nate
Possible that the engine was decked and re stamped need to clean off that area carefully and take another look or have expert look at pad
Wes

 

It's hard to believe someone would accidentally stamp the wrong code. The engine was rebuilt so that can very well be the truth! Unless I can get at the tank sticker, I will have to pass on this one.

Is the tank sticker visible with a bore-scope cam?

 

I think something is amiss with everyone's decoder. I looked at several sites that list CJK as an LT-1 automatic.

I thought LT-1's only had manuals ?? and I see that car has A/C. Not with the Lt-1

 

Supposedly there was a miss-print in publications from decades ago that listed CJK as an LT1/Auto/AC. It was corrected and most publications list CJK as a 350/270 At.

The problem with this car is, lets say it came from the factory with the CJK stamp. There is no way to prove that it is correct for the car. No build sheet, no window sticker, no documents at all. Forever it may as well be considered a non-numbers matching car because it is not correct per what is available for proof.

 

Does the partial VIN match the car?

 

Yes it does

 

Did you buy it yet?

 

Yes.......or done at the time of the tranny swap.

 

No, the car will for ever be a non-numbers matching with the discrepancy. To some it wouldn't matter. For me I'd rather wait and find one that matches in as nice of condition.