64 engine numbers - 283 or 327 ???

[CynthiaChebultz]

The engine in my 61 has Engine Code on front stamp pad T0427S The Casting Number and Casting Date were totally covered up by a throttle linkage bracket, once we took the bracket off we found Casting Number 3858180 - which is a 327ci from a 65 and 66 Passenger, Chevelle and Corvette.

Farther left from the Casting Code and perpendicular is the Casting Date of D17 64, with a smaller 64 (or April 17, 1964) April 64 seems a little early for a 65 or 66??

Next to the Casting Date is the Casting Clock which was added to some Saginaw blocks sometime during 64. The clock appears to specify that the block was cast during the second hour (due to the clock pointing at the second dot) of the second shift (due to the screw head in the center being round instead of flat) - which would have been around 6pm, April 17th. The Casting Clock also had a large 6T in front of it (not sure what this means) .

Now the big dilemma is the past couple of previous owners that I've talked to say the car had a 283 in it, which is how it was advertised when I bought it. My book says that this casting number is a 327???

Anyone have any other reference materials or input??

I've also been trying to track down other numbers on my car, here is the post:
Thanks!
Cynthia

[Joe L.]

Re: 64 engine numbers - 283 or 327 ???

Cynthia------

The block is a 327 cid engine block which was cast in Tonawanda, NY on April 17, 1964 and assembled at Tonawanda, NY on April 27 of that year. The "6T" and 2 digit year code for the casting date establish, for certain, that it was a Tonawanda-cast block. The "T" suffix for the engine code establishes, for certain, that it was a Tonawanda-manufactured engine. The casting clock really has no particular relevence. The information which it provides may be a curiosity, but little else.

The block was originally part of an engine configured for installation in a 1964 full size Chevrolet passenger car with Powerglide transmission and 250 hp engine as evidenced by the "S" suffix code for the engine. Although it is generally regarded that the GM #3858180 block was first used for 1965 model year applications, this engine pretty well says that this casting was first used for very late in the 1964 model year. That's really of no relevence to your situation, though.

What you do know, for sure, is that this engine is a 327 cid engine and definitely NOT a 283. A 327 block starts off as a 4.0" bore and you can't make a 283 from a 4" bore block. So, it's either 327 cid or it's a larger cid engine if it's been overbored. The previous owners' assertions that it is a 283 is incorrect. That's not to say that did not believe it to be a 283 but, if so, then their belief is not consistent with reality. Period.

If the engine is as originally configured and outfitted, it will have GM casting #3795896 cylinder heads and a GM casting #3844457 intake manifold. Of course, those components could have been changed.

[Jack H.]

Adding on...

to the solid info Joe Lucia has given you, there's no question in my mind your car's factory original engine has 'departed'.... Yes, 1961 was the last year for 283 CID engines in Corvette, those engine blocks were cast in Saginaw vs. Tonawanda, and were casting number 3756519, primarily, with the random usage of casting number 3789935 observed from approximately VIN number 9500 through the end of the '61 model year build.

[Joe L.]

Re: 64 engine numbers - 283 or 327 ???

Cynthia-----

By the way, if you're going to have a 61 with an incorrect block casting number, you're much better off with an incorrect 327 block casting number than with an incorrect 283 casting number. From a "judging" perspective, they're going to be "about equally incorrect". From a performance standpoint, the 327 is a LOT better than a 283-----more power and torque with the same weight and general configuration. Except for "numbers", you can configure the 327 to APPEAR just about identical to the 283. This way, you have a correct appearing engine (which is the only thing that matters to 99% of the folks that look at these cars) and you get the extra power and torque.

So, it ain't all bad.