Very Early 1966 427 blocks

[Patrick B.]

Larry, I was very surprised that the ground-off 942 block that Colvin pictured in his book was installed in a April Corvette, and I have no theory about it. It looks just like the one I had seen, but that was in a very early 67, around serial number 900. Seeing one in an early 67 didn't seem strange at the time since I had not yet encountered the F-17-6 351 block. I think the ground-off 942 block I had seen was cast in May.

I am still of the opinion that all 942 blocks were cast before the F-17-6 351 block. I don't think that any were cast later for the sake of the parts system. Later model year parts were used as replacement parts if they would fit with even with minor accommodations. Since most 427's were cast between 1 and 6 months before assembly at Tonawanda, there was storage area at least for 427 blocks. So some 942 blocks could have around to cover early 351 supply issues. The Colvin block must have been a extreme example of first-in last-out parts stocks or there was a mistake about the vin that was reported about it.

Here is another ground off casting example at same time period. I had a set of 858 heads that had ground off casting numbers with 391 casting numbers stamped on. They were the same font hand stamps (probably the same set) that were on the block I saw as well as the Colvin block. The were cast in mid and late June of 1966.

[Mark F.]

Patrick,

Do you know if 942 blocks were used in other Chevy models (Impalas, etc.) after the 351 block was introduced for Corvettes ?

[Patrick B.]

Only the 351 blocks are listed in the literature about 1967 427 full size Chevies, and only the 427 385 hp hydraulic lifter 2-bolt block version was offered.

I have never seen any evidence that a block or head casting and its newer replacement were ever cast simultaneously. I thought I had when someone in this thread reported a F-6-6 942 block but that was only because my memory was faulty. I thought that I had once had a F-1-6 351 block, but I subsequently checked my records and it was really dated F-17-6. I am convinced that the casting of 351 blocks began sometime between June 7 and June 17, 1966, and that 942 blocks were not cast after that date.

I am also sure that 67, 68 and later 427 and 454 blocks would have been sold as service parts for 66 427’s. Since bare service blocks came with the correct cam bearings installed, there would have been no oiling problem even if the original grooved cam was reused. GM even sold an adapter to use cartridge oil filters on the later blocks designed for spin on oil filters.

It seems our discussion of early 66 427’s has turned into a discussion of late 66 427’s. It is still an interesting topic.

[Mark F.]

...I have never seen any evidence that a block or head casting and its newer replacement were ever cast simultaneously. That makes perfect sense to me...even if the newer replacements were in there "testing" or "prove-out " trial runs, you'd think the cast ID or other codes would have had a unique identifier...like "XXX" or something to distinguish them from their predecessor part...I thought that I had once had a F-1-6 351 block, but I subsequently checked my records and it was really dated F-17-6. I am convinced that the casting of 351 blocks began sometime between June 7 and June 17, 1966, and that 942 blocks were not cast after that date.

I am also sure that 67, 68 and later 427 and 454 blocks would have been sold as service parts for 66 427’s. Since bare service blocks came with the correct cam bearings installed, there would have been no oiling problem even if the original grooved cam was reused. GM even sold an adapter to use cartridge oil filters on the later blocks designed for spin on oil filters. Interesting...didn't know that...

It seems our discussion of early 66 427’s has turned into a discussion of late 66 427’s. It is still an interesting topic. Agreed - the anomalies always bring lots of questions begging for explanations that may never come .

Thanks for your knowledge and insights, Patrick...