Hi,

   I just purchased a1971 Formula  400. The motor has been replaced. The Vin # is 28L130331 the casting # is XX 31988. What motor is in this car??

Help

Frank

Hi Frank, it's a 1971 400 CID 2 barrel. The attached pic is from an appendix of Rocky Rotella's How To Build Pontiac V8s.

Sorry - here's the pic.

Thanks. The XX is on the back of motor where the casting # should be. The heads are 16. The front letters are either WC or WG. the second letter is not punched very good. Where the 31988 is I was expecting to find 979 . . . . the # for a 1968 motor.

Found it.  481988 cast number. Had to have daughter with younger eyes look and take picture. Again thanks. frank

The casting number confirms that it is indeed a 400 engine block from either '71 to '73. The casting date of the block can be found on the distritbutor pad at the back of the engine. That will confirm what year it was made.

For '71, a #96 or #99 head would be correct for a 400 engine. The #96 has the more desirable 2.11 intake and 1.77 exhaust valves.