Just lifted my heads on my Y, chasing low compression on 1 cylinder, and find that although i have the ECZ-G heads, one has the small part no., and the other, large.
I seem to recall that the large part no. heads were posted, and the small ones were not.
Is that the only difference, eg. compression ratio's, etc.?
Neither head has the "steam" holes, is this worth doing?
Tia, Al.







South Australia

Have not heard about the difference in font casting sizes being an indicator of posted heads or not.

I have heads with both casting font sizes that are posted and also not posted.

The large lettered heads are always installed on T Birds.

The heads were cast at two different factory locations.Its more about a date of when the heads were cast.The later dates were the posted heads.

Oldmics

Thanks Oldmics, neither of the heads are posted.


.


South Australia

My understanding is that none of the small font 'G' letter heads were posted.

As Oldmics indicated, the large letter 'G' heads may be 'posted' or 'un-posted' depending upon when they were cast. John Mummert's web site indicates that pre-May of 1957 'G' heads were un-posted. Sooo... there were a lot of 1957 Fords and Mercurys likely assembled with un-posted heads. '58 Mercury's with y-blocks are a good source for posted 'G' heads.

In my work with the two series of heads (small 'G' and large 'G'), the combustion chambers appear to be identical. That said, my comparison of the intake and exhaust porting indicates that different sand cores were used in casting the two series of heads! Both the intake sand cores and the exhaust sand cores were different in the small letter 'G' heads. The striking difference to me is the shape of the bowl area under the intake valve and the port area closest to the exhaust manifold.

Other than 'posts', I've observed no other differences in large letter posted or un-posted 'G' heads.

Based upon information shared on this 'Forum', I also am not adding 'steam' holes to y-block cylinder heads or engine blocks that do not already have them.

What I don't know about casting date codes would fill a book.

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

The small letters are cast in Dearborn and non-posted, the large are Cleveland and can be either way. Best way to check is stick your finger in the hole and feel for the post. Both have the same volume combustion chambers.



Ted Eaton photo

   God Bless.   Tim                           http://yblockguy.com/

350ci Y-Block FED "Elwood", 301ci Y-Block Unibody LSR "Jake", 312ci Y-Block '58 F-100, 338ci Y-Block powered Model A Tudor

tim@yblockguy.com  Visalia, California    Just west of the Sequoias

Your pictures are great, slick56. Sometimes my computer shows pictures in Forum threads, and sometimes it does not. I went back to re-read your question, and the pictures were there that I did not see previously of the cylinder head casting letters!

Clarification (because your pictures didn't look that different when I looked at them )...

1) small letter 'G' cylinder heads have casting letters 1/4 inch in height

2) large letter 'G' cylinder heads have casting letters 3/8 inch in height

3) notice, too, that the casting letters are oriented in different directions on the two heads in relation to the intake manifold mounting surface.

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

Ted Eaton put this up on 5-16-2013 when someone else was looking for 'head posting info.'
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Here’s the link to the ‘how to’ pictorial.

http://forums.y-blocksforever.com/Topic47592.aspx

I've also gone through some of those other threads and fixed the links within them so they will function again.

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And here's another link.

http://forums.y-blocksforever.com/FindPost57138.aspx

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I think the first link is the step-by-step detailed procedure that you're looking for. The second thread has some other good pertinent info though, also.

ADDENDUM: I JUST TRIED TOGGLING THE ABOVE LINKS, DID GET TO THE CORRECT PLACES, BUT NO PICTURES! PERHAPS THIS IS RELATED TO MY COPYING AND PASTING THE INFORMATION???

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

It seems to be working correctly.


Lawrenceville, GA

I think the first link is the step-by-step detailed procedure that you're looking for. The second thread has some other good pertinent info though, also.

ADDENDUM: I JUST TRIED TOGGLING THE ABOVE LINKS, DID GET TO THE CORRECT PLACES, BUT NO PICTURES! PERHAPS THIS IS RELATED TO MY COPYING AND PASTING THE INFORMATION???



Yes, the link is working fine, pics are a-ok.


That is the article i was looking for, thanks heaps


.


South Australia

I dont think you have to worry about posting them unless you plan on supercharging!

55 Vicky & customline

58 Rack Dump, 55 F350 yard truck, 57 F100

59 & 61 P 400's, 58 F100 custom cab, 69 F100, 79 F150, 82 F600 ramp truck, 90 mustang conv 7 up, 94 Mustang, Should I continue?