[Carousel72TRed]

I pulled an engine out of a 69 GTO I bought for parts back in the late 80's and put it in my 69 GTO because I trashed my original motor and it has a YC code (says YC 090386 and the casting number is 9790071 on the block. I have looked up the YC code and the block would indicate it came out of a 69 Catalina 2 Barrel. I was told by a Pontiac enthusiast that 69 GTO's built in California might have come with the YC block because of California's stricter pollution laws even back then. The YC block has a 10.5 compression ratio vs. the standard 10.75 compression ratio for GTO's. Any information on this would be greatly appreciated.

Thank You
Carousel72TRed

[north]

YC was never used on GTO's. In 1969 all Pontiac engines met all California rules so there were no California specific applications for 1969 model year cars. The compression ratio of Pontiac engines in 69 was related to heads (combustion chamber size) not the block. There was a 2 bbl no charge engine option for the GTO (with auto transmission only) in 69 but it was a low compression (8.6) 400-265 horse engine identified with an XX code on the block and 45 heads. The correct application for a YC block is the standard engine in a Catalina or Executive if ordered with an automatic transmission. It was rated at 290 horse and had 46 heads which were 10.5 compression but small valve.

[OG68]

AFAIK there was no special 'California' engine for 69. Earlier years often required a different air cleaner and/or smog pump but by 1968, California and Federal regulations were the same. For a few years anyway...

Anyone with more insight on this please correct me if I erred.

[Carousel72TRed]

Thank you very much Ultimate Warrior. Looks like from my engine code ID info my motor could have come from either a 68 or 69 full size Pontiac. I currently have 16 heads with a J247 date code on the GTO and my original 62 heads with a B049 date code.in the tool shed.

Carousel72TRed

[north]

That makes sense since the YC code was replaced with YD a few weeks into the start of 69 production. The change was when they changed the angle of the valve seat cut in the small valve engines. Your YC is a 1968 model year engine produced in late 1967. 16 heads are probably from a 68 GTO or 428 engine and the 62's are the correct heads for an automatic base GTO engine (YS).

[johnta1]

The engine block should have a partial VIN on it. It would show what year it is and the factory the car/engine was originally built at.

[Carousel72TRed]

Thank You Jontal,

I have tried numerous times to read the date code on the block but can only read the 9790071 engine ID on the back of the block. On the front is a YC Code with a 090386 number next to it.

Carousel 72TRed

[johnta1]

The partial VIN is lower on the engine (passenger side still) by the timing cover. The stamping is vertical, also usually hard to find/read. (lots of oil, crud and paint)

[Carousel72TRed]

Thank You Jontal,

I will check it out today. There is a date code on the back LH side of the block but I can't read all of it. The letter looks like an L or M and did they use an L or M designation for being built in December?