Milling 1.6 Hydro Head

[Jory]

I'm building a 1.6NA that was overheated. The head has no cracks, but I could pull an .011" feeler gauge out when I straight edged it.
Is there a special milling process due to the pre-chamber inserts? Also, the original head gasket was a three hole. Will milling the head necessitate a different head gasket thickness or can I go back with a three hole gasket?
I'm going to plastiguage the cam tomorrow to check for journal warpage.

[Quantum TD]

With that much warp, you really need to have the head straightened or replaced. The warp is not just on the surface of the head, it extends into the cam journals as well. So, even if you resurface it, it will wear your camshaft journals and probably will run a bit off. You really should have it straightened and then resurfaced. Otherwise, they'll just be taking off way too much material.

Also, in order to warp a head that bad, the thing had to get quite hot. I wouldn't proceed with any sort of rebuild without inspecting the pistons, and minimally replacing the rings.

Or, if you don't really care about how long it runs, just mill it and slap it bad together. It will probably run like poo (if at all) and will likely burn oil from cooked oil scraper rings.

The amount you mill off will not affect the head gasket thickness. It's determined by the amount the pistons project above the block. But, I would measure it to be sure. There are too many people out there with that same misconception (milled head=thicker gasket), to be sure that the gasket you pulled is correct for the block.

As for milling, the best way is with a fine grinder. Don't let them use a table sander (like a belt-sander), and conventional cutters tend to pull the pre-chambers out. So, a very fine lathe or cutter is needed. Some people pop out the prechambers and then mill. Then they measure the depth for each prechamber and grind them individually. Frankly, I don't know which is worse: pulling the chambers or cutting them in place. Either way, you'll probably want to peen them in place before you reinstall the head

[rabbitman]

And the cam is probably putting LOTS of force on the bearing surfaces.

[Jory]

I didn't elaborate in my original post. I'm doing a full bottom end rebuild with a .040" overbore.

I was afraid the cam journals would be a problem. Guess I'll know for sure after I plastiguage it tomorrow.

[Quantum TD]

I'm sure there are good shops in Nooga. It seems like an old mecca for machinists (from the train days), and should be again with VW coming in.

I know a really good shop here in Murfresboro (Neal Cylinder Heads), but that an hour+ drive from Nooga. If you know Sal (in Chicamauga: big in the VW scene down there), he may have some leads on shops.

[maxfax]

And the cam is probably putting LOTS of force on the bearing surfaces.

Just as a side note, did you check for warpage with the cam in or out??  IF you remove the cam it may even be off more..   

AS far as milling, Quantum is spot on..  Some have talked about having the head planed then having the cam journels line bored to straighten everything out..   That's works, but IMO thats removing more metal and usually more money than necessary.. 

[Jory]

I'm sure there are good shops in Nooga. It seems like an old mecca for machinists (from the train days), and should be again with VW coming in.

I know a really good shop here in Murfresboro (Neal Cylinder Heads), but that an hour+ drive from Nooga. If you know Sal (in Chicamauga: big in the VW scene down there), he may have some leads on shops.

Sal's father lives across the street from me 

I've got a shop in Rossville I'm considering using. Making a trip to Murfreesboro wouldn't be out of the question though. Your engine's only as good as the machining that goes into it.

Just as a side note, did you check for warpage with the cam in or out??  IF you remove the cam it may even be off more..   

AS far as milling, Quantum is spot on..  Some have talked about having the head planed then having the cam journels line bored to straighten everything out..   That's works, but IMO thats removing more metal and usually more money than necessary.. 

I checked it with the cam out. Hadn't thought of that though.

[Powered by Spearco]

Unbolt the cam and if it teter-toders in the jurnals, its junk.

[maxfax]

Unbolt the cam and if it teter-toders in the jurnals, its junk.

I've had them straigtened from that point and work (once again on the indestructable crack engine), but it is a gamble when they're that bad...

[Jory]

Well, looks like I'm in need of another head casting 

Dropped the cam in and it rocked quite badly. I've the feeling that picking up another head will be cheaper than having the machine work done needed to fix this head.

[theman53]

someone was saying you could take the head and have it heated to almost molten and pressed flat again. Might help with the top side. I think that was what they were getting at anyway. Might be worth checking into at least before buying a "new" one.

[maxfax]

I'm not sure exactly what the process involves but yes, basically they bend the head back so that the cam journels are in line, and the surface is much closer..  Then they skim it and they're good to fly..

The head I referred to earlier the was really bad cost me about $360..  That was for a ready to install and good as new end product..

Things done were: pressure test, straighten, skim, replace valve guides and some valves..  Grind the rest of the valves and set the valve lash.. They even peened and welded the cracks between the valves (though they were not leaking and within the tolerance allowed) and peened the pre chambers in there...

[RustyCaddy]

They even peened and welded the cracks between the valves (though they were not leaking and within the tolerance allowed) and peened the pre chambers in there...

What is the tolerance for the cracks between the valves.  i know i have seen it somewhere but can't find it using the search function...not to hijack this thread...sorry about that.

[Quantum TD]

Well, looks like I'm in need of another head casting 

Dropped the cam in and it rocked quite badly. I've the feeling that picking up another head will be cheaper than having the machine work done needed to fix this head.

Probably not a bad idea. I wouldn't junk the head. Anything can be fixed with the right knowledge, tools and/or money. But yeah, it would probably run about $400+ in work to get that head right again.

[745 turbogreasel]

What is the tolerance for the cracks between the valves.  i know i have seen it somewhere but can't find it using the search function...not to hijack this thread...sorry about that.

If  a nickel goes in there, you might  possibly have a problem, but  equally well might not.