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#1
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How much to Cut my X-Heads
If the build up recomends cutting J heads 040 but I am going to use X heads would I mill them the same?? this is to get the combution chamber down to 65cc. These are going on a 318.
thanks diego |
#2
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I'm probably mistaken, are'nt X heads 63 cc already?
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#3
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Before you cut them at all, CC the chambers and see where you are starting from. CC specs are usually just a factory specification, and often times chamber volume between heads and even between chambers on the same head can vary greatly.
Also, before you put that head in the milling machine, check the condition of the valve seats and valve heads. Valves sunk down into the valve seat or ground till they are thin can add a fair amount of volume to a combustion chamber. I don't have the specs, but 63 cc sounds about right. But that is a blueprinting spec, often stock chambers are much larger, even on unused heads with new valves. |
#4
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The blueprint specs are usually in the low 62-64 cc range, most all open chamber smallblock heads untouched will go 72 or more cc. To reduce the chamber volume 1cc you must remove .0048 from the head surface, for each .010 removed from the head you must remove .0095 from the intake face of the head.
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#5
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Mopardad is right on the money! You'll definitely want to cc them cause they may have already been cut B4. Chances are they have being that old of a head. With the 318 you'll probably be working with a negative deck height, so you'll want to get the cc's down on the low side of the blueprint specs, say 62-63 cc's. Also I'd get the thinnest head gasket that I could find. Fel-Pro I think is .038 thick. Wedgehead
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#6
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Mopardad nailed it right. Listen to Stoga before you do anything.
Just remember that you'll need new pushrods. You just lowered the head and by the same, shortened the pushrods. Remeasure before ordering. Take care in this step. My "J" heads are 72cc. They are the same casting as the "X" heads. |
#7
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Do you have to cut a valve relief into the block on a 318 for the 2.02 valves?
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#8
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Only if you want max HP with a high lift cam, or so Iv'e been told. Please let me know if this is right or wrong.
diego |
#9
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My J's cc'd at 60cc now that i took another .010 off!
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#10
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so what was the total amout you took off? what do you think your compression will be?
diego |
#11
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The heads were done by hughes by the previous owner only I can't read the work tag very well, so I don't know how much had been taken off before i got them. I will be at 9.25:1 with .025 head gaskets. This is a '72 low compression 340, or should i say was?
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