[rowco]

I have a SR 400 block the#9799915 is on the
back of the block this tells me its a 1970
R/A4 block but the date code is 1231. What
gives? Also the # SR85531 is on the front
of the block.Do the numbers mean any thing?
It has 4 bolt mains and came from a 1970
GTO Judge.

[rowco]

I have a SR 400 block the#9799915 is on the
back of the block this tells me its a 1970
R/A4 block but the date code is 1231. What
gives? Also the # SR85531 is on the front
of the block.Do the numbers mean any thing?
It has 4 bolt mains and came from a 1970
GTO Judge.

[Dan Jensen]

Rowco,

I'm going to take a stab at your questions. If I am wrong, somebody out there will certainly correct me!

The "SR" of the "SR85531" engine unit number on the front of the block indicates that it is a "service replacement" block.

The "1231" date code may actually be "I231" where the first chararcter is actually the letter "I" which indicates the month (A=Jan, B=Feb,.... I=Sept), "23" means the 23rd day of the month, and "1" means 1971. The block was then cast on September 23rd, 1971. There has been discussions that the letter "I" wasn't used in the date codes because of its confusion with the number 1. So make sure the date code is real clean and check it again to be sure it does show an "I".