I bought a 1972 Pontiac Grandville at a farm auction the other night.The owner announced before the bidding started that it had the (H.O.) engine in it! My question is if there really was a H.O. option in a Grandville in 72? I might add that on the sticker on the radiator support it states near the bottom "Requires 91 octane fuel or higher". Just curious what kind of compression and horsepower this engine would have?
Thanks in advance  

If the heads have casting 7F6 on the center exhaust ports, the exhaust ports are round and the block has code YB/WM/WD or YE, then yes it is a 455HO.  Otherwise no.  I don't think a Grandville could have been ordered that way.  

Hi,
I think the seller may have been referencing what he thought was a Super Duty(SD), not HO.

Here is a link to a 1973 Grandville order form.  It only shows the 400 and 455 available in 1973 although 1972 may have been different.  check the VIN.  If the 5th digit of the VIN is Y then it is a 455 250hp (not SD).

I have also included a link to the 1973 engine chart.  It shows the 250hp 455 available in the B body but the 290hp 455 (SD) NOT available in the B body.  Hope this helps som.  If course 1972 could have been different.  

http://grandvillebypontiac.com/documents/1973%20Engine%20ID%20Chart.pdf


http://grandvillebypontiac.com/documents/1973%20Grandville%20Order%20Form.pdf  

Got a chance to scrap the grease off the block today and it says Y4.I thought it would be 2 letters instead of a letter and a number.How many horse will this engine have stock? Thanks  

Y4 is a 400 ci rated at 185 HP.  See the 1971 to 1975 engine id chart at the link below. 12th row down from the top.

Note: this engine also shows a 2bblcarb.  If you have a 4bbl then the intake and carb may have been swapped from another engine.

http://grandvillebypontiac.com/documents/1973%20Engine%20ID%20Chart.pdf  

Somethings wierd here.The block on the side clearly reads 455 near the front on the drivers side but it is also clearly stamped Y4.It is a 4bbl and all the date codes are within acceptable. Guess it was stamped incorrectly thats about the only explaination at this point.  

Maybe the engine is not original what is the date code which can be found by the distributor and also what is the casting number on the back of the block.  

Y4 is a 220 hp 455 for 1972  

Y4 code was also used on 1973 400 170/185 hp and in 1974 455 215/250 hp depending on heads  

220 horse 455 in 72 Thanks