[vader007]

This is the first time I'm doing a head gasket job on my D16Z6, so apologies in advance for any newb questions. I took off my head and took it to a local machine shop to check for flatness and resurface. Without taking a straightedge to it first, the machinist said that it's definitely warped because the head always warps as soon as you take off the head bolts. (Is this true?)

When I got it back, there were visible milling marks and a few scratches on it. I can feel the parallel ripple lines from the machining using my fingernail. It doesn't quite feel as bad as like an LP record; its feels maybe closer to 200 grit sandpaper, though I can certainly at least count the ripples by using fingernail alone. (It was WAY smoother before I gave it to him, fingernail wouldn't even feel anything.)

I don't have a profilometer to determine the roughness average. The machinist wouldn't tell me what the RA was, just said it will work with my MLS head gasket.

From my research, it seems like MLS head gaskets (I'm about to install a Fel-Pro MLS, which allows for up to 80RA) need to be very smooth in order to seal right - in theory, I shouldn't be able to feel the lines by fingernail.

First pic (the still dirty head) is from before taking to the shop.

The rest is after taking to machine shop for resurfacing.

Does this look okay? Am I freaking out over nothing? I'm not shooting for a performance build, I just want to keep it stock. Maybe the camera flash is exaggerating some of the scratches, though some are "feelable" by hand - are those anything to worry about?

I've never been to this machinist before but it appears he does do work for a bunch of local repair shops.

 

[slo_eg8]

looks fine. and no, it does NOT always warp when you remove the head bolts.

wonder if he remembers how much he milled off, might be helpful to know

 

[drtalon123]

Nope, your good. Make sure surfaces are clean and dry and put it back together.

I would guess just by the pictures he's definitely below 40ra. Vertical milling does that, its normal.

The FelPro blue coating will soak up all those record grooves, flatness is key

Also, head doesn't always warp out of spec when removed. It really depends on the number of heat cycles the head sees. Checking for flatness tells you this, your machinist should have done this to know how much to mill off.

 

[vader007]

Thanks for the responses. He said the computer allows him a max of 0.004 inch but couldn't say exactly how much he milled off. He did put it in a straightening machine before milling though. He mentioned he thinks the previous owner resurfaced the head before, because there wasn't much material on it, but I didn't see any evidence of that (I have service records going back to 1993, none of it mentions such a major job). Am I correct that the 3 circles around the perimeter of the surface of the head (visible in the middle pic) are the wear indicators? If so, there's still like 1mm of material above those indicators.

Is it possible to determine what the previous owner milled off? I thought it was as simple as measuring the current height minus the originally spec'ed height, but he said no its not possible to determine.

I guess the other thing I'm trying to figure out is whether he's a decent machinist to work with for future jobs.

 

[mattliston]

Im pretty sure those 3 buttons in the casting are for showing where the head is at. I normally see those gone with people who do serious head shaving for compression increases.

 

[transzex]

Not enough was milled to even worry about. Search and you'll find a picture I posted about the pads with measurements. You haven't even touched the first pads.

 

[TheToaster]

Nope, your good. Make sure surfaces are clean and dry and put it back together.

I would guess just by the pictures he's definitely below 40ra. Vertical milling does that, its normal.

The FelPro blue coating will soak up all those record grooves, flatness is key

Also, head doesn't always warp out of spec when removed. It really depends on the number of heat cycles the head sees. Checking for flatness tells you this, your machinist should have done this to know how much to mill off.

Nyet!!! OEM HG ONLY

The Felpro has some little BS crug that flakes off and looks like trouble..

Copper spray it if youre paranoid.. Watch Nelson Race engines, they use some sort of industrial tar/shellac/sealant type stuff