Ok so I have taken my spare head all apart and labeled things except for the valve assemblies. Will the machine shop want them in the head to do a pressure test? What and how does a pressure test work? Will he need new valve guides before I bring in the head or can he do the valve seat/valve work before I purchase them.
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First time getting cylinder head machined - some questions
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Well, that depends on if you want them to do a pressure test! But my experience with 'pressure testing' is looking for cracks in the coolant passages...
And yes, the valve guides get changed before a valve job- that insures the valve's
concentric with the new guide. The shop can get the guides, and they'll be able
to match any price you can get. AND they'll be able to get the right size-
the OD's are available slightly over, so that you can get a better fit in the head.
Usually I drop off a head casting with 12 valves, springs, cups, retainers and locks. And stem seals.
It comes back with the valves installed, and I do the cam assembly.
That seems to work pretty well.
tnow, sometimes I just mess with people. It's more entertaining that way. george graves
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When I have a head done, I take the head and the valves to the machine shop. They'll inspect the head, surface it, replace the guides, cut new seats, and grind the valves (in that order). It isn't unusual to need new exhaust valves. I'll then install the seals and valve springs and drip test the valves. If that test shows that the all seal I'll finish assembling the head and install it.The car makes it possible, but the driver makes it happen.
Jim Levie, Huntsville, AL
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The guys who've done heads for me all liked to assemble the valves- but that was
simply to keep each valve in the port it was lapped into. (yes, there's an argument for
not lapping, but, yeah)
And for anything other than a street motor, I'll usually take it apart for
inspection and checking. Why? I'm kinda paranoid. Once I found something,
so now I always look. Which means, the machinist doesn't install the seals.
But if you don't have a spring compressor, there's nothing wrong with the machine shop
doing the valve assembly. They do it every day, in a fraction of the time it takes me.
tnow, sometimes I just mess with people. It's more entertaining that way. george graves
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