[Ron H]

I have an engine ID code 0310492 YA. I am unsure how to determine the year of manufacture or size of engine for this block. Depending on the year it can be a 400 350 or 455. It is supposed to be a 67 400 block. Can someone confirm this for me?

[engineer]

only one YA listed in 67 was a 400 2 bbl. look at block, how many freeze plugs on the side, how many motor mount bolt holes, on the side the 455 or 350 number might be cast, get the block no. from pass side rear top and by dist. hole, get date code.

[Phil from Canada]

This information is from the Wallace racing site at http://www.wallaceracing.com/enginesearch4.htm and simply expands on the information given by engineer. I will keep directing people to this site unless told otherwise. It is a great site.

"Pontiac used the same codes on different year blocks.To differentiate them it will have to be determined what year the block is.Next to the distributor hole there is a casting number that has a letter with 2 or 3 numbers. The letter is the month of manufacture- A=Jan. B=Feb,etc.
The next number or two is the day, but sometimes the factory left the first part off, i.e. 5 could mean 5,15,25.The most important is the last number,it is the year of Manufacture it is not always the model year,as most blocks are cast a few months before the car is made. In addition 1966 and earlier blocks had 2 freeze plugs on each side of the block.
1967 and newer had 3 freeze plugs per side.
1969 and older blocks had 2 motor mount holes per side.

Starting in 1970, most blocks were cast with 5 motor mount holes with the mounts using 2 bolts in line with 1 higher up in the middle.Some 1977 and later blocks only had 3 holes that used the newer mounts. This means you can put a 455 in about any Pontiac car with that car's motor mounts, but if you want to use a 428 block in your 1970- Firebird you'll have to modify the frame mounts or make an adapter.

Starting around 1969 Pontiac cast a 2 digit year number next to the distributor also. They also cast the engine size on the sides of the block,usually in front of the motor mounts or between the freeze plugs.

Around 1967 Pontiac also stamped the VIN numbers (see pic above) next to the timing cover about even with the timing marks on cover.This will start with a 2 (for Pontiac) then the last digit of the year then the car serial number starting with the plant letter.These are usually covered with oil and crud, and probably hard to see.This will tell you if this is an original motor."


Phil

[Ron H]

Yeah I was all over Wallace's site. I am not where the block is. I asked the guy who has it to check this site and then get me the rest of the numbers. Thanks for your help. As I scrolled down the engine block codes for 67 then later years all the way to 78 the YA was used with 400's 455's and 350's. I just found out the heads are a 6X-4 with date codes of C315 and C115. So I am thinking this engine is a '76 350.

[Phil from Canada]

Ron 6X-4s were also used on Pontiac 400 engines around the 76-78 time frame. They were used on the W-72 engine.

Phil

[pontorquer]

Hi Phil ! Looking from behind the block or standing , look on your right above bellhousing bolting contour , behind rear cylinder , you will see block casting #9786133 if your block is a 67 400 ! Good Luck Canadian fellow Pontiac Enthusiast ! Pontorquer P.S. Pete McCarthy Pontiac musclecar performance 1955-79 is a great book to buy ! Some poeple call it the PONTIAC BIBLE !