1966 BB Block Identification

[John C.]

Need help with a 66 BB block casting? The cast # is: 3904857 (might be 4851?). Also cast near cast # is "HIPER". I can't find this # anywhere on internet or my Chev V8 casting # book? Also had F21 stamped on the trim plate. This engine came attached to 66 BB car from a woman's that her grandfather left to her! I was in Hawaii and it sold before I could get home! Any help appreciated!

[Bill L.]

Re: 1966 BB Block Identification

John:

Typically a '66 big block will run a "3869942" casting block ------

Are you sure you are reading 4851 and not 4351??? I suspect that might be what you have --- in that case it is a "3904351" casting and as such is typical of a '67 and not a '66.....

Take a closer look --- you may have a '67 block -----

Hope this helps --

Regards
Bill

[Richard M.]

Re: 1966 BB Block Identification

Looks like a 427CI 3904351 block casting. I cropped and magnified the photo.



Check the cast date just ahead of the starter, upside down. It'll be a letter(A to L, .....including I) followed by several numbers. The last digit should be a 6. Very late 390& 425 HP '66's could have used the '351 block according to my references.

[Joe L.]

Re: 1966 BB Block Identification

Need help with a 66 BB block casting? The cast # is: 3904857 (might be 4851?). Also cast near cast # is "HIPER". I can't find this # anywhere on internet or my Chev V8 casting # book? Also had F21 stamped on the trim plate. This engine came attached to 66 BB car from a woman's that her grandfather left to her! I was in Hawaii and it sold before I could get home! Any help appreciated!

John------

It's almost certainly 3904351. I doubt this engine was originally installed in any 1966 unless, possibly, a VERY late 1966. What does the stamp pad look like?

[John C.]

Re: 1966 BB Block Identification

Unfortunately, by the time I could get back to the mainland the car was long gone so I never got to see the stamping or the cast date on block. By this time the car had a 70 350 but the owner (now dead) had this complete BB engine, carb shielding etc that he intended to bring the car back to when he bought it new in 1966! Probably, a 67 block was close enough.I thought the "hyper" casting might be for a high HP BB? Thanks for all of your help; John

[Patrick B.]

Re: 1966 BB Block Identification

John------

It's almost certainly 3904351. I doubt this engine was originally installed in any 1966 unless, possibly, a VERY late 1966. What does the stamp pad look like?

351 blocks were being cast by June 1, 1966. I have pictures of the 351 block that was original to 1966 Corvette Vin 27089. The really surprising feature of it was that the casting required the early type rear cam bearing for the 942 block rather than the 67 style rear cam bearing one would expect for a 351 block.

[Gary J.]

Re: 1966 BB Block Identification

I have a '66 BB K19 build date with a 942 block.

[Patrick B.]

Re: 1966 BB Block Identification

K19 would be a June or July car depending on whether it was an AO Smith or a St. Louis body. At any rate I'm sure your block was cast in April or May since June 942 block don't exist. The end of 66 and beginning of 67 model years produced some unusual big blocks. I have seen early 67 cars with 942 May blocks with the casting number ground off and the 351 casting number stamped in, and a few real 351 blocks in July 66 cars but certainly not all.

The peculiar aspect that I wanted to call attention to was the use of a 942 type rear cam bearing in an early 351 block. Even a very knowledgeable engine rebuilder would put a non-grooved cam and the second design rear cam bearing in a 351 block. However, that approach would lead to a lack of cam and lifter lubrication in the early 351 block factory installed in 66 Corvette #27089 (casting date F-15-6, T0707IP). Beware, and use the right cam and bearing in early 351s whether you find them in late 66s or early 67s.