What would be a fair price to pay fora pair of posted G  heads that are rebuildable?  Ray

There are essentially three different ‘G’ heads.  On all of these, the part number ‘ECZ-G’ will be located under the water jacket boss where the intake manifold bolts to the heads.  A picture showing that part number and where it is located will be in one of the links below.

The earlier ‘G’ heads introduced in 1956 are the small letter G heads and all of these are unposted.  The big letter G heads were introduced for the 1957 model year and those cylinder heads made at the Dearborn facility were all unposted.  The ‘G’ heads made after mid-May at the Cleveland facility were the posted variety.  Posts are an additional support added within the heads to minimize any flex taking place at the decks.  Whereas the earlier heads had the intake ports cast integral with the decks, the intake ports for the G heads were raised for increased flow which left an internal gap between the lower part of the port and the inner surface of the deck.  Hence the need for ‘posts’ when the compression ratio is increased and/or the heads are milled.

The service manual is very specific in not milling any more than 0.010” from the decks of the unposted G heads but I have been getting away with as much as 0.025”.  The later model posted G heads can tolerate milling the heads much more than this as I have gone as much as 0.070” and got away with that.

The following links will provide additional information and pictures.
http://forums.y-blocksforever.com/FindPost113735.aspx
http://forums.y-blocksforever.com/FindPost113752.aspx
posted vs non posted

Lorena, Texas (South of Waco)

Somebody probably will post photos; in the meantime, search "Ford Y-block ECZ-G heads" and click on images. Unlike other Ford/Mercury Y-block heads, with the exception of 471 & 113 heads, the intake valve is noticeably larger than the exhaust valve. All Ford/Mercury Y-block heads have the same size 1.510 exhaust valve, but ECZ-G, 113, and 471 heads have 1.925 intake valves. 

Can somebody please tell me how I can identify G Heads?

Thanks,

Ray