|350/400/455||Displacement numbers cast into block on driver's side near the front freeze plug. [You should also look on the opposite side too--check photo.]|
||"428" located on driver's side near the center between the freeze plugs.|
||No "421" numbers located anywhere; look for a square machined area on front passenger side deck where the block meets the head.|
||No "389" numbers cast any where on the block; look for notch on passenger side deck where the block meets the head.|
Year of the block
What year is the block? At the rear of the engine at the top near the distributor hole can be found the important casting numbers that reveal the year of manufacture--the birth year. The fourth digit indicates the year of the casting. So, if you have examined the rest of the block, you can easily ascertain the year the block was manufactured. The other info in the string may be helpful, but is not usually to relevant. The first letter, could be A through L, signifies the month. A=Jan, B=Feb, and so on. After the letter are two digits; 01=1, 25=25. Remember the last digit is the year (0-9).
Where's the engine code
Sorry, but you really can't accurately determine the year of the engine by merely knowing the engine code. You have to put all the information together to be certain. Pontiac used two-letter engine codes in different years in various cars. In later years, Pontiac added a corresponding VIN number to the block. Whatever the case, you need to examine the front passenger side of the motor. If the VINs match, that determines the engine option from the factory. Look to see what's there. Based on my observations Pontiac engines started to include VINs on the block in 1972. [This paragraph was updated 2-25-00.]
Putting it all together
For example, you come across an engine that looks pretty clean. So you start to check it out. You look at the engine code and see it has the letters WF. So you take a peek under the distributor and see several casting numbers but the last one in the string is a 9. This could be a '59, '69, or '79. You need to keep going. Look at the freeze plugs next. You look and see three (3). The equation narrows it to a '69 block. You look further, scrape away the grease and low and behold you spot the casting numbers 428 between the two freeze plugs on the driver's side. A big smile erupts on your face, your respiration and heart beat pick up, you hear "Born to be Wild" in the background and your reach for your wallet... Hello--come back. Checking a Chiltons manual that covers 1969 tells you that the motor was rated at 370, and powered a 4 speed Grand Prix.