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By MplsMike - 10 Years Ago
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Hi all,
I found a set of matched "5752 113" heads for sale locally. If I want to upgrade the heads on my car, should I be looking at G heads or 113 (assuming I won't buy Mummert's heads)? When looking at used heads, what should I pay attention to? The guy is asking $275.
thanks,
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By pegleg - 10 Years Ago
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The 113's have slightly bigger chambers, but supposedly flow very well, as good as G's. See Mummert's site for a cylinder head comparison. If they're good, they would be worth the asking.
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By NoShortcuts - 10 Years Ago
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One member's thoughts...
There are three versions of 'G' cylinder heads
- small casting letter ECZ-G heads... none of these were 'posted' when they were produced regardless of production date
- large casting letter ECZ-G heads... heads cast before May 1957 were NOT posted (John Mummert info.)
- large casting letter ECZ-G heads... heads cast beginning in May 1957 and through production year 1958 for Mercurys were posted (John Mummert info.)
- All 'G' heads have a 69 cc combustion chambers
- All 5752-113 cylinder heads are 'posted' and have slightly larger combustion chambers measuring 72 cc that yield a slightly lower compression ratio with whatever y-block you use them on.
In evaluating the cylinder heads you have available to purchase, consider looking carefully at:
- the condition of the deck surface and the combustion chambers. Look for pitting in the cast iron surfaces caused by erosion that was the result of exposure to moisture created by condensation from sitting in an outdoor environment over time. IF pitting exists on the deck surface, can it be eliminated by milling the head surface? Pitting in the combustion chamber area, if significant, can indicate that the valve seats may have to be fixed by installing new seats. Too, significant pitting in the combustion chamber can be a source of pre-ignition. -NOT good!
- with a micrometer, determine the thickness of the pads on the cylinder heads that are located below the exhaust ports and adjacent to the spark plug holes. When the heads were manufactured by FoMoCo the pads measured 1.000 Note the recommendations below from John Mummert's web site regarding how much the heads you're considering purchasing can be machined to true the deck surface.
All of this information considered, posted, unposted, combustion chamber volume differences... I would base my purchase decision on the condition of the deck and combustion chamber surfaces (no pitting desired) and the thicknesses of the cylinder head pads (if they are less than 1.000 in thickness, the heads have been previously reconditioned... how much is left that can be removed safely?) Any of the 'G' or 113 heads will work fine for those of us that are assembling street and highway application vehicles, IMO
Hope this helps you. 
See this web site address of the 'Y'Block Guy', Tim McMaster, for helpful cylinder head information
http://yblockguy.com/techtips/postedheads.html
From John Mummert's web site:
Do to the thinness of the deck surface of some Y-Block cylinder heads,particularly the ECZ-G heads, it is recommended that unposted heads not bemilled more than .025". Posted heads have been milled up to .045"without trouble..
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By MplsMike - 10 Years Ago
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Thanks, this is very helpful!
What does "posted" versus "unposted" mean?
I don't know if pictures of the heads can provide much information, but to my untrained eye, there does seem to be a fair amount of pitting. Maybe I should talk Jerry Christenson into taking a ride over to look at them!
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By NoShortcuts - 10 Years Ago
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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.
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By charliemccraney - 10 Years Ago
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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.
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By PF Arcand - 10 Years Ago
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One item missed in this discussion is; "cracks"! Pay close attention for them, particularly near the centre exhaust valves area. Use a magnifying glass..
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By NoShortcuts - 10 Years Ago
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YES! GooD, important point, Paul.
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By DualQuad312 - 10 Years Ago
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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
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By DualQuad312 - 10 Years Ago
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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
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By DualQuad312 - 10 Years Ago
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If you don't feel any casting then there un-posted
Jeff
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By LordMrFord - 10 Years Ago
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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.
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By Ted - 10 Years Ago
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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
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By LordMrFord - 10 Years Ago
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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.
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