Resurfaced heads..... machined or belt sanded?

[Ben_Pow!!]

Okay, not a machinist here, something seems a bit screwy. I had my heads resurfaced a long time ago by Napa. I got them back and the surface was nice and shiny, perfectly smoothe. I had another set of heads done recently by a performance shop Pro-Motor which a lot of people seem to like the place. When I dropped them off, he asked if they had been previously belt sanded. I didn't really think about it until I got the heads back and you could see the tooling lines. He used what appeared to be a CNC mill w/ a large-diameter round disk with the tooling mounted near the outside of it. Were the heads belt sanded smoothe before? I would assume this is not a good idea. One of my concerns is the machining lines can be felt w/ my thumbnail, is this going to be a problem? I did a little google image search and found both situations, anyone have any inseight on this?

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the reason the heads are off is a graphite head gasket failure, bought multilayered steel this time.
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[colt45 gto]

once the heads are milled they should be smooth you shouldn't feel anything.

sounds like a poor job to me. dunno what they mean about belt sanding? never heard of this on heads before.

[UTRacerX9]

Some shops don't have the proper tooling to mill a cylinder head. But if they have a decent sized belt sander, you can usually fit a V6 cylinder head on there. It isn't the most professional way of doing things, but unless your heads were severely warped, they should be fine.

[j2k4]

once the heads are milled they should be smooth you shouldn't feel anything.

sounds like a poor job to me. dunno what they mean about belt sanding? never heard of this on heads before.

If you were told they were "belt-sanded" I'd be going over them every which way with a straight-edge to check them.

As far as milling, generally they should be pretty damn smooth, with just the faintest tool marks.

Depending on the application/head-gasket type, some shops will run a higher feed rate on the mill to give the head a bit more tooth to "grab" on the head surface - less of that going on, these days, but.

[CoreyB]

I would never belt sand heads.

[colt45 gto]

i would claim for a new head if a machine shop belt sanded my heads, only a milling machine can get a perfect surface.

[AaronVR4]

I used to rebuild heads in high school. Would belt sand before competitions.

[Ben_Pow!!]

Yeah, I'm sure the surface itself is not warped after the job, but it's the machining "grooves" I'm concerned about. I imagine if they are too deep, this will allow gas to escape and right into the oil/coolant passage they pass through, but I don't know. Like I said, it's not very deep, but you can certainly feel it w/ your fingernail and visually see them. This shop is always busy w/ work, so I have a pretty good % of beeing OK. I'm going to give him a call and see what he says about it.

[colt45 gto]

post a pic up ben

[green-lantern]

Mine had these groves you speak of and they were done by a reputable shop also. I didn't like it at first but was assured it was OK. I haven’t had any trouble yet.