*There are many questions surrounding the 61 casting numbers. First of all, the 61 casting number (the correct one) is a higher number than the '62 casting number. This is because the 409 was not scheduled to make its initial appearance until the 1962 model year. Because of increasing pressure from sources such as the Ford 390 and the Pontiac 421 as well as the change in NASCAR rules outlawing multiple carburetor set-ups, the 409 was brought out early in a down-tuned version that could be conceived as a bored and stroked 348 although the 348 water jackets were too thin to take the over-bore needed. This is all documented and factual information. The following is a theory we have developed based on those facts:

There were five different possibilities of casting numbers for the '61 model based on different situations.

1.Casting Number 3795623 was the way that GM intended the casting number to read.

2.Casting Number 3995623 was most likely a mistake. GM did not use casting numbers in the 3900000s until the '65 model year and therefore '61 engines with this number were probably the result of the wrong number being cast.

3.Casting Number 3795623 with the 7 stamped in. This was probably one of the miscast engines that was caught before it went out. The incorrect 9 was ground off and the 7 stamped in to make it correct.

4.Casting Number 3788086. This is, of course, the '62 casting number and is doubtful but not impossible that any of the '62s made it into the '61 automobiles.

5. 3795623 all stamped into the block. We have seen this before and in most cases feel that it is probably an attempt at a counterfeit although it may be possible that GM took some 3788068s late in the model year and ground them down, and made them read 3795623.

We believe that most of the 61 409 blocks were cast in Dec.1960 and that production was halted temporarily by May 1961.

1962 3788068
1963 3830814 has "×" on Block
1964 3844422 has "×" on Block
1965 3857656 has "×" on Block

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