[79 Phoenix]

Originally Posted by 'ol Pinion head

Originally, the 500557 400 blocks used the 2.75" register cranks. That practice lasted at least a year/ well into mid '76 engine production. Later '76 model 400 blocks received the smaller register cranks, do remember checking a few.

For many years i had a Pontiac V8 engine core program going. On occasion I would pick up '76-78 500557 shortblocks, then simply shell them out for the good condition smaller register 400 cranks, as well as oilpans, timing covers, valley pans, & hardware. Two of the '77 500557's I stripped down, the stock cranks had the correct recess for a pilot bearing. Both of those cranks were needed in 4speed W72 TransAm engines where the owner had spun a rod bearing & was still wanting to run the stock small register 11" cast flywheel.

Block date is "A156" which I assume is January 15, 1976. Apparently my crank was cast later in the year, as the register is 2 1/2". Does this make sense?

Also I do plan on removing the pan to replace the rear seal. I should be able to find the crank date then.

I am considering installing a BOP 2-piece seal like link below...
https://www.ebay.com/itm/225319050821

[Mister Pontiac]

Originally Posted by 79 Phoenix

Block date is "A156" which I assume is January 15, 1976...

I see the big "75" cast by the Distributor hole, so I'm betting that date is A155, or Jan 15, 1975. Hard to tell for sure in the pic, maybe hard to tell in person as well. Try a wire brush over the casting date and see if it doesn't become more of a '5' at the end.

It seems unlikely to me to be cast with the big number 75 by the distributor and be a 76 engine, which A156 would be.

[johnta1]

The best way to ID the year is by the partial VIN on the block.
The pic of the date code is hard to tell for sure if the last digit is a '5' or '6', but I think it is a '6' (1976)

I have seen some blocks with the 2 digit cast year for the next year of production. (would have to check notes if any in 1976 though)

[Quad]

Originally Posted by johnta1

The best way to ID the year is by the partial VIN on the block.
The pic of the date code is hard to tell for sure if the last digit is a '5' or '6', but I think it is a '6' (1976)

I have seen some blocks with the 2 digit cast year for the next year of production. (would have to check notes if any in 1976 though)

examples;
1976 year before,
1973 no year,
1972 year after.
No sure what the big numbers are supposed to mean.

[79 Phoenix]

Originally Posted by Mister Pontiac

I see the big "75" cast by the Distributor hole, so I'm betting that date is A155, or Jan 15, 1975. Hard to tell for sure in the pic, maybe hard to tell in person as well. Try a wire brush over the casting date and see if it doesn't become more of a '5' at the end.

It seems unlikely to me to be cast with the big number 75 by the distributor and be a 76 engine, which A156 would be.

Yes I wondered about that too... But I just cleaned it off better and checked again and it's definitely A156.

[79 Phoenix]

I just checked VIN code on the block. 8th digit from the end is also a 6.