Expensive mistake

Have a 427 Chevy on the dyno at the moment. It is a 1966 four bolt casting, originally from a Corvette according to the guy who owns it. Unfortunately, the original owner was so paranoid about someone stealing his 427 that he stamped his name and driver license number over the factory numbers and ruined the value of the block. These early Corvette blocks sell for up to $10,000 to a collector.

Since it isn't a numbers block anymore the current owner hot rodded it. Stroked it to 496, added Trick Flow heads and a solid street roller cam. It is a nice engine, makes 630 hp and 615 torque. Going in an El Camino. Should be a blast.

If you don't care about numbers, it's not a mistake!

Here is another very similar engine that is in the shop at the moment. This is another 1966 427 but the factory engine numbers are still on it so it can be decoded as a 1966 427/425 or a L72. The 427/425 had solid lifters, 780 Holley carb, a bunch of special parts and only came with a manual trans. This one came out of a passenger car but the VIN isn't stamped on it so don't know what. Probably Impala SS. The passenger car 427/425 are much rarer than the Corvette L72 engines since most people buying a big car didn't want a high compression, solid lifter engine with a manual shifter.

I think this one his getting hot rodded too but I don't know the details.

it is only a mistake if the owner of the parts think it is, correct Andy

It's not as much of a mistake as the guy who ground off the VIN number of a 1970 426 Hemi out of a 70 Hemi Challenger Convertible so he could stamp in the VIN number for his 66 Hemi Satellite.

I thought VIN numbered blocks didn’t begin till 68, so a correctly dated 66 block could be called a numbers engine?

Corvette guy's don't care about the numbers on the block originally, they put them on during "restoration "

Exactly, but a 1969 casting date block that you ground off the VIN that started JS27R0B would never be correct, but the guy did it.

The VIN pad on the oil plan rail didn't even exist on Hemi blocks (or big blocks) till 68.

THATS what a mistake looks like

Wouldn't decking the block take the numbers off?

Yep, that is a big problem with the high dollar Chevy blocks. Lots of blocks lost their VIN numbers during rebuilds back in the 70's and 80's. Eventually people figured out to leave the VIN area unmachined but that requires modern equipment. The old surfacing equipment used 40 years ago just did a complete pass and the VIN number and engine ID was destroyed.

If that block was installed in a car it would have the serial number on the pad. They started on corvettes in 1960

Well, stamping Corvette blocks - or should I say re-stamping - to have the desired #s has been going on forever.
Obviously, that usually requires decking, but it's been a refined art for some time...

Yeah I've seen some mention of that. Sounds like GM only stamped the VIN on special combinations and even a 427/425 Impala SS wasn't special enough to get a VIN stamp in '66. Without a VIN we're just guessing on the Impala SS. Could also be a Biscayne. No way to know at this point but it was a rare bird whatever it was.

Well their first mistake was building a Chevy......Todd

As has restamping Mopar blocks.................

That was not a mistake, that was owner stupidity.

I have seen it done to very collectable guns too.

The good thing about a block is it can be machined and corrected, whereas you don't mess with gun serials.

With those heads and a solid roller cam I would have expected more hp ? Don't know the rest of the specs but 600hp in any street car should be a plenty.

Comp 286R-10 peaks at 6000 rpm. If he wants to go racing he can slide in a bigger cam. The heads should be good for 700 hp with a bigger cam and bigger carb.

www.Mochevparts.com

That's a good find for somebody who doesn't care about numbers.

What makes it really rare is that it wasn't sold for high dollar to a corvette owner who needed an unstamped block so he could end up with a numbers car.