Identifying my buick 350.

[hidetanner7779]

Hi guys. I am new to the site but have learned a lot from here already. What I have is a 70 350 out of a GS that was given to me. The engine code that is stamped on the block is SP. After some research here I have learned that it is one of the few that broke the 300HP mark. I am in the process of rebuilding it, and as I was cleaning the block deck there was another number stamped into the deck just to the right of the engine code. That number is 424. Any ideas as to what this number means?

Any help with this will be greatly appreciated.

[sean buick 76]

I do not know what the number means however the SP is what is important. The engine left factory as a 315 HP version as you found out... That is all there is to know really except the date codes and VIN number which do not really change anything.