Head trueness


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By RayCarter18 - 11 Years Ago
I just checked my head on my 292 what is the max tolorance for flatness I have no gotten more than .005 in gaps in a few spots most of it have .002 or less
By NoShortcuts - 11 Years Ago
With the newer composite gaskets the surface variations you're finding are not of the concern that they were when we had to use the metal-only gaskets, Ray.

John Mummert worked with BEST Gasket in the development of their gasket offerings for the y-block.  The head gaskets in particular are interesting because more pressure is applied where it is needed while areas previously gasket-ed are eliminated from coverage because no purpose is served.

Look at the picture on this web page to see a comparison of new and old to visually see what I'm referring to...
By RayCarter18 - 11 Years Ago
Well I have new gaskets but they are not like the ones you mention with some of the gasket cut out mine are like the old metal ones just new material.
By NoShortcuts - 11 Years Ago
I'm not 100% on this, Ray...  I THINK Dennis Carpenter, for one, is offering the older metal style head gaskets.

Victor, Fel-Pro, McCord, BEST, and others have gone to the composite head gaskets.  They'll give you a seal that you can't count-on into the future with the old 'tin' ones.

The down-side is that the final thickness of the torqued composite gaskets reduces the engine's static compression ratio by increasing the effective combustion chamber volume.

Here's some specific head gasket information from an article on Ted Eaton's web site:
The entire article can be viewed at http://www.eatonbalancing.com/blog/2012/06/30/head-gasket-volume-calculation/
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Here are some known head gasket values for the Ford Y-Block engine.

Best Gasket for regular bores                12.91” X 0.046” = 10.00cc
Best Gasket #572B (3.937” bore)         12.99” X 0.046” = 10.12cc
Best Gasket (4.030” bore)                    13.35” X 0.046” = 10.69cc
Fel Pro #7999PT (Permatorq Blue)      12.95” X 0.044” = 9.62cc
Fel Pro Multi-Layer (old design)          12.60” X 0.039” = 8.07cc
Fitz 3 layer (metal,comp,metal)           12.80” X 0.048” = 10.25cc
Fitz 2 layer (metal,composition)          12.80” X 0.050” = 10.67cc
Fitzgerald #0645 (metal/metal)          12.76” X 0.031” = 6.58cc (40+ yrs old)
Flatout #FOG9123.5 (3.830” bore)      12.64” X 0.040” = 8.33cc (copper)
Ford steel shim C1AE-6051-B               12.68” X 0.025” = 5.24cc
Ford steel shim C3TE-6051-E               12.68” X 0.026” = 5.45cc
McCord p/n Mc6392M                           12.79” X 0.048” = 10.24cc
ROL Gaskets #HG32120                      12.79” X 0.045” = 9.61cc
SCE copper                                         12.99” X 0.042” = 9.24cc
Victor #1176TC composition                12.95” X 0.043” = 9.40cc
Victor #1176BS steel shim                  12.68” X 0.025” = 5.24cc

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The above cc numbers represent the effective volume of the area within the gasket-ed circumference distance and height of the compressed gasket!  Notice the striking difference between the steel shim gaskets and the various composite offerings!  This is added to your actual cylinder head combustion chamber volume!  OUCH!