gmctd wrote:
An aluminum cylinder head conforms to the cast-iron block surface when head-bolts are torqued to spec
- meaning, the block surface level is most important, here
- normal requirement for milling aluminum head is not warpage, but large nicks and gouges in the surface between the combustion chamber and bolt-holes, water passages, and cylinder-to-cylinder which require welding operations
- this requirement for milling an aluminum head is to bring welded repair areas back to surface level, then very minor cleanup resurfacing the entire head if necessary, due to induced local warpage from welding heat
- other than that, don't get carried away, here: aluminum head warpage will conform to flat cast-iron block surface after torquing to spec, will re-settle during repeat heat\cool cycles during normal engine operation
- soft aluminum does that, where cast-iron is un-yielding and cannot
- key is hardened flat-washer necessary to reduce twisting resistance and evenly distribute applied torque\tension around the bolt-hole surface
- you can mill a warped head deck to flat, but what do you do about the still-warped surface that the head-cover with camshafts mates with?
- the cylinder deck surface may now be flat, but the head-cover surface still conforms to the original warpage which will not now even\settle out during torquing
- head cover surface must be in plane with the cyl surface to prevent warping the camshaft carrier, with it's precision camshaft bores, hydraulic lifter bores, etc
- resultant induced warpage ain't even good for this assembly
Wow, thanks for that! Sounds like it should be left alone if it's within the factory .004" spec then? The machine shop told me today that it's 3-4 thou out, but said that "it's not all that exact checking it with a feeler gauge, and there could be a dip that's worse"... Would you have them shave 3 thou and call it good, or leave it alone? I will be using ARP's and this motor has the 2 hole gasket. When it overheated it blew the fluid out of somewhere fast. I was too pissed to even see strait (stranded in a remote area), so I can't remember where all that fluid exited, but he said the water jacket and combustion chamber have no cracks. I shut it down the moment I saw the temp skyrocketing.
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One I bought that way, one is my daily driver and I earned it since I boiled it over once (it barely leaks, just tiny bubbles, and loses about a cup every 100-150 miles), another one had the rockers go and I was on a long grade so by the time I could get off the road it boiled over. The latest one is hopefully just a leaky EGR or other hose, but I sure hope it isn't a cracked block, or head gasket, because 4 for 4 is ridiculous!
