View Full Version : 84 Accord warped head can be fixed to OEM specs?
offthahook
08-20-2008, 03:56 PM
Is this possible? I bought a head for $15 from a guy who told me it had been run hot and it was warped. I took it to a good machine shop and he said it was about 10-12 thousandths inches warped. That is quite a bit of warpage and he didn't think a milljob would fix it properly. However, he told me that they bolt the head to a piece of cast iron and bake it for a few hours at 600 degrees. Then, it can be straightened to within OEM tolerances. I had never heard of this before, but the machinist acted like it's pretty common. I always thought that if a head was warped, it needed replaced. Apparently, an aluminum head can be reshaped to get it back in spec. True?
I also recently heard that you shouldn't mill a Honda head. I can't believe that to be true, so you can mill the deck of a Honda head, right?
Ichiban
08-20-2008, 08:12 PM
I've never heard of heating and clamping, but I suppose it's possible. Honda heads have a maximum machinability of .010 or so I believe, so if the head is warped .012 and milled .010, and the tolerance for warpage is .002, then that puts you at the top of the tolerance then.
2ndGenGuy
08-20-2008, 10:49 PM
I've had two Honda heads milled before, one of them has seen about 30,000 miles so far and is still running strong. The other lasted until my friend sold the car. And actually the head that is on my hatch now was warped and is still running good. So that's actually three that I know of.
I never have heard of clamping it either... I figured if they were warped beyond spec you tossed them out. Actually the one on the Civic that has had 30,000 miles on it was warped beyond spec. He said it was bad, but probably will be just fine once it's milled true. So far, so good. My dad daily drives that car now.
Milling has the negative effect of retarding the cam timing, due to the cam gear having to rotate slightly since it's now closer to the crank pulley. The possible good effect is that it bumps your compression and might slightly increase power output.
AccordB20A
08-21-2008, 11:44 AM
would be good if you had an ajustable cam gear tho right
Hauntd ca3
08-21-2008, 01:14 PM
there is nouthin wrong with what the guy said bout heating it up and bolting it to a big chunk of iron.
is fairly common practice specially with big long jaguar heads.
aslong as the place that does it has a good rep for such work and offers a warranty on their workmanship
i'd go with it
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