Hmm... there was a major head gasket problem with the dragster but it seems to be gone when we repaired the crank position problem and got a stable AFR with bigger injectors.


Hyvinkää, FI

Head gasket sealing seems to be more of a problem on heavily milled unposted ECZ-G heads than is a cracking problem.  Without the posts, the decks do flex thus compromising the head gasket seal and my experience with unposted G’s being milled 0.060” proved to be a head gasket failure on both heads in that particular instance.  The factory manuals recommended no more than a 0.010” mill on the unposted heads but it’s been found that up to 0.025” of mill is satisfactory in most instances.  Unposted heads prior to the ECZ-G heads are designed differently within the water jackets and as such, they do not have the same 'unposted' problems as the G heads.
  
The 113 heads are my iron head of choice for any performance work.  Once past the compression ratio issues due to the larger chambers, the 113’s do tend to outperform the G heads in both unported and ported versions.  Part of that has to do with some unshrouding of the valves as a result of the chambers simply being larger specifically around the valves.  I’ve seen the 113’s milled as much as 0.080” and still holding up fine but the factory posting of all those heads would be the reason that works.
 
Here’s the link to a past thread with pictures going into detail on how to identify posted heads.
http://forums.y-blocksforever.com/FindPost6764.aspx

Lorena, Texas (South of Waco)

Has anybody cracked unposted and unmilled heads with cylinder pressure?

Because that Hollow Dragster got still unposted heads and boosts had been up to 29 psi and still holding down the pressure.
So I think its quite impossible to destroy the unposted heads without milling them too much.

IMHO unposted heads are not boat anchors.







Hyvinkää, FI

If you don't feel any casting then there un-posted

Jeff

If no one explained it to you yet and you haven't learned how to check for posted and un-posted heads.... Stick you finger in the large hole in the center of the head, feel towards the sides you should feel casting a wall-like surface.... You should be able to check this in a couple places on each head at the large holes in the head there about 3/4" diameter....

Jeff

The head in the pic looks like it hasn't been cut..... I, look at the 113 # on the deck surface..... Using the "pads a reference stinks to say the least.... There not consistent from on head to another. I, don't think Ford ever machined both sides of those "pads" and because of this it makes them inaccurate and inconsistent with one another. I, say look at the #'s 113 and any letters on the deck surface... If they appear crisp then most likely the heads never been cut this is my reference.... If you measured a brand new head I'll Guarantee you (I, have a pair  N.O.S.) you'll get different readings!  Also 113 truck heads have 8.8 compression ration and if you use the Felpro gaskets which you most likely will they'll drop to 8.6 :1   Good flow heads but the you'll develop less compression and actuality less power. G-heads are 9.5:1 using felpro gaskets.... Check out John Mummert's site he has all the spec. He deserves the credit .... He went through the time and trouble to figure this stuff out.....

Best Regards,    Jeff

YES!  GooD, important point, Paul.


NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

One item missed in this discussion is; "cracks"!  Pay close attention for them, particularly near the centre exhaust valves area. Use a magnifying glass..   


Paul

For street use, I'd go with whiscruber set I cam across first.  So get the 113s.  Hmm, this scrub thing is kind of annoying.  That should be which ever.

But, the first thing to do is to see what is on your car, if you have not already.  After more than 51 years for the youngest Y block, don't assume it is now stock.  Maybe it already has the heads you want.



Lawrenceville, GA

Back-up to my posting above.  Hover over the web address pertaining to Tim McMaster, 'The Y-Block Guy', and toggle the address.  By clicking on Tim's address, it will open the 'posting' information' link on the Internet.

If I were you, I'd talk Jerry Christenson into making the trip with you when you go to see the cylinder heads available for purchase.  Jerry's an invaluable resource.  -Very knowledgeable and experienced!  Consider taking a wire brush with you to clean the heads off the best you can to get a look at those metal surfaces along with a micrometer caliper to measure those pads.

Let us know how you make out.  Best wishes on your hunt. 


NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York