Asking this on another board, but the answer to it is going a little slow. With a couple of experts on tonight, I'm hoping to have better luck here. Here goes.

I have a '62 Block, Casting #3789817. It is a 327 Casting Number, but the engine is a 283.

The subject was talked about once or twice a long time ago, but I haven't seen any info on this block for a while. Back then there were at least some who had different opinions on it.

I'm trying to verify that what I have is actually an underbored 327.

Any info would be appreciated.

The sorce that I have lists it as a 283 for 1962-64 and a 327 from 1962-67. It also shows some other numbers for this dual application. It could be a casting number for a later replacement block. There are also some seperate casting numbers shown for 283 and 327 for those years. Will need to dig deeper tomorrow.
In 1957 the 265 block (not same as a 1956) and the 283 block had the same casting numbers and the 265 was just under bored.

It's funny that you have mentioned that, as I had one of them too at one time. It could have been bored to a fresh standard size 283.

I'm thinking the 817 block will be the same way. It has been a bit of a mystery thru the years.

As per 1964 parts book-
Casting numbers 3782870 0r 3789817 are used on NEW 1962-64 327 blocks AND 1957-62 283 blocks. This does not necessarily mean that the block installed in a new 1962 (or any of the other years) would have had these numbers. The new blocks sold through parts were more or less universal and they used the latest casting and adapted it to the older models. This was done to reduce parts inventory.
I see no reason that the 283 version could not be bored to 327 bore - but not sure as to what could be used for pistons due to the 327's longer stroke. It was simple in 1957 as the 265 and 283 had the same stroke.
For year block was made finding the casting date would be necessary. Should be raised numerialsshch as E4 or L1 or?..If a new block would have been installed the stamped engine code number may be missin or would have been transfered from original block.

Chev Nut,

Do you believe the 817 was a replacement block only or do you think it was also in regular production?

Also after boring it to a 4 inch bore, couldn't one just use a 327 crank and pistons?

I had checked the date code, but would need to check it again to see what month and day it is, but I remember the year being '62. Also need to re-check the engine code, but it will probably be a "D".

I am not sure if it would have been a replacement block casting number but the number falls into the range used in 1962. I would be quite certain that the 327 crankshaft and pistons could be used to convert the block. The only thing is that after assembling it I would turn the engine over a few times to make sure nothing hits against the block, such as crankshafr weights etc. They could have machiened out some area for clearence of a rotating part. Nothing that couldn't be taken care of and I doubt if this would even be a problem.

Appreciate the info.

Bill

Keep me posted.

Bill,
I had this seen this before on two other 62's that I had owned and they were original production 283 engines. FYI they were both late production cars (April and June)with Tonawanda engines
John

Thanks John.

Your engine builder show be able to do a check (ultasound?) to determine cylinder wall thickness before attempting to bore it out that much. Should have enough wall thickness, but better safe than sorry.