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The only information I could find regarding the BK is that one post regarding the aero marine 427-L88 which has a BK stamp, unable to find a partial vin on this block anywhere.
The only information I could find regarding the BK is that one post regarding the aero marine 427-L88 which has a BK stamp, unable to find a partial vin on this block anywhere.
I looked all over the place both on the web and in my archive of printed information and couldn't find any BBC with the suffix BK, however, I have no information on suffixes used by aftermarket marine engine suppliers, so the above post is likely correct. It is possible that GM sold BBCs to aftermarket marine engine suppliers which were either stamped by GM with the "BK" suffix or the engine builder stamped them. It's possible that, in this case, Aero Marine used "BK" as its suffix
The casting number, 3963512, indicates a block that was used from '69 to '71 in Corvette 427 and 454 applications and was available in either 2-bolt or 4-bolt main bearing versions. It was unusual because it was used for both 427s and 454s.
My wild-assed guess is that block was once an iron-head L88, which would make sense for a marine engine running "wet stacks" (ie: water-cooled exhaust manifolds) and using fresh or salt water as coolant.
In passenger car applications, L88s were normally seen with aluminum heads but, considering the anticorrosive technology available 50 or so years ago, fresh- or sea-water would have eaten up alum. heads in short order so GM made iron head L88s available for marine applications. This "Aero Marine" was an engine builder that, presumably, had access to marine L88s.
Last edited by Hib Halverson; Sep 7, 2023 at 05:13 PM.
The only information I could find regarding the BK is that one post regarding the aero marine 427-L88 which has a BK stamp, unable to find a partial vin on this block anywhere.
A Marine 427 will not have any VIN on it at all.....it's a 512 block so this is probably what it is......a damn good block, but nothing really special about it.......what is the crank pt#? That can give you more insight as to what it is.....
We had a guy on here 3 years ago with one of these, the whole engine, and he was so hopped up about it that he made post after post about how rare and special it was and when I (and others) told him it was cool, but no holy grail he attacked me and got strange as **** LOL....saying other members accounts were mine and I was a troll.....LOL....
Anyway.....throw that pan away.....been fabbed to a deep sump and repaired poorly......
Probably the strongest Mark 4 block there was........be an awesome base for a 496......
What are you going to do with it?
but how does T05217 become a month and day of month if the last characters are BK?
Not sure....but the downward stroke on a Z is straight....but a 7 has a little curve....and no bottom stroke...that is a machine mark....
Blow it up big and you will see it....
IDK...
Not sure....but the downward stroke on a Z is straight....but a 7 has a little curve....and no bottom stroke...that is a machine mark....
Blow it up big and you will see it....
IDK...
Jebby
I can see the same thing that it looks like a 7 but that would blow the standard date format and a marine engine would not have a partial VIN. One of life's mysterious.
I thought we all agreed that there was NOT a partial VIN. So, marine engine makes sense?
And that is absolutely a "7", not a "Z". I can't explain it either, but I love a mystery!
How about a restamp by someone not familiar with the date configuration. Maybe the 7 represents the last digit of the year or did marine stampings include the year?
OP, if your engine is indeed a marine engine, the stamping of T0521 7BK indicates a Tonawanda engine assembled on 5/21 with a 7BK suffix. The 7 does indeed represent the year (1967, 1977, 1987, etc)
Thanks to derekderek for the listing. Sorry 7BK does not appear in the listing. Does your engine have brass freeze plugs? Scrape some of that shiny paint off of the freeze plug and look for brass versus steel. How about petcocks on the block to drain the jacket? If not, a threaded hole on each side of the block at the lowest portion of the jacket, to accept a petcock?
Here is the stamping on my marine 454. T04226XH corresponds to Tonawanda engine assembled on 4/22 of 1976. 6XH can be found in the attached listing.
