No such 455 SD
 

Al/lpr
Hi all, first post. I am pretty knowledgeable, all things GM. I came a crossed a so called 1974 SD 455 rebuilt which should have been a Y8 490132 also there is a W8
Same year and HP both have casting # 490132, but the Y8 is the only one listed as a SD. Now this is where the plot changes. this guy bought this T/A brand new with a SD engine in 1974. drove it into the Ground, started to restore many years later rebuilt the Engine, body was pretty bad put QT,s on it reinstalled engine trailered it to his house, while taking it of the trailer the sub frame separated from the body. So he pulled the engine and scraped the car, now it is for sale. He sent me the casting # Y9 525740 clear as day. I looked it up and no such engine was ever produced with those numbers. Can any one here shed some light on this. I have not been stumped for many years

I am pretty sure my 1974 non-SD 455 T/A has a Y9 block in it. The car isn't handy, so I'm going from memory. The Y9 motors were standard 455 D-port engines but built with HEI distributors. This was a very late production change that occurred around late June or July 1974. There are some threads on this site that discuss when the HEI was cut into the 1974 production. Incidentally, I picked up a supplement to the 1974 shop manual that lists the Y9 as a 455 with HEI. When I bought my car, it was a one owner, but I wasn't convinced the engine was original because I couldn't find Y9 in the shop manual. I found the VIN in the block, so I took a chance.

Mike is correct.
The Y9 is a late 455. The 525740 is probably the Engine Unit Number (EUN).

Have him look for the stamped partial VIN on the engine block about half way down, close to the timing cover passenger side.


:)

He probably sent you a picture of the stamped engine unit number and pick code. poncho-mike is correct on a 455/auto (non-SD) with HEI having the code Y9 in later '74. Car was probably a late July '74 build. But, Y9 was also used in newer engines too ('75-6 400, '77 350), so the casting at the back need to be seen too.

Thanks for all the input, I must go and see for my self now and get all the numbers. I'm doing a Radical 79 T/A. I'm interested in this engine ,to replace the 455 olds I have in mock up now. Big HP pump gas Engine 750 HP Olds, I think I can get 900 out of the 455 Pontiac. Kauffman heads and a Big Roller. This build deserves a Poncho Engine. At first I thought it started out as a 400, turns out that in 79 GM offered a 403 with an auto trans, a 400 Pontiac with a 4 spd manual, or a 301 N/A engine, for $1600.00 less, I was fooled it had a 301, did not find out until tear down. As soon as I can figure out how to up load photos, I think many will like some of my current Pontiac Builds, 69 GTO judge, 72 Ventura, 67 Catalina Convert Radical Custom. I'm very new to the Blog seen

Every pontiac deserves a pontiac engine! Good luck sir...