Head Flatness

[Xit40]

Here's the deal. My car is blowing white smoke and peeing coolant into the overflow bottle....pretty much my head gasket is gone. Ok no big deal. Im gonna pull the head off in the next day or two and take it to my machinist to check it for flatness before I put it back on. Then I'll have him cut it if necessary or just clean it up and smooth it out. What is the limit for warpage? I know it's probably in my FSM, but my CD-ROM isn't working right now so if someone could help me out I would appreciate it. Also when I'm putting it back together what is a good way to prep the block for the new head gasket? I'm going to ask my machinist what he recommends but I would like to hear how some people on here did it to their engines. Thanx a lot

 

[tom04841]

When i rebuilt my stock block after the balance shaft belt broke and killed my head, i used a plastic gasket scraper to get the majority of the gasket off, then used ALOT of 2" 3M medium roloc conditioning discs (maroon ones). Then went over it with a very fine blue disc. And finished off with a super fine gray disc. Popped on my new mls head gasket w/ arps and it is holding 25 psi just fine.

 

[DirtyBirdRacing]

Hi,

The service manual says that you want the head to be 0.002 inches or less from flat, with a service limit of 0.008 inches from flat.

Bill

 

[Xit40]

Ah beautiful. Thanx that's exactly what I wanted to know. I thought it was something like that but I couldn't remember. Although I think the gasket I'm using if I remember correctly requires it to be less than .005. Anyone else have block prep recommendations?

 

[Big Woo]

I would caution the use of 3M type roloc disks. I have seen people remove too much material with them, and actually create an uneven surface. I would reccomend a stone for cleaning the block deck surface.

 

[Xit40]

The disk thing did seem a little off to me, but I did ask how people cleaned up their head and block and it obviously worked out for him. I'm going to be using AJUSA's head gasket which I purchased from Jackson Auto Machine. I had the head checked today and it's definately flat. Less that .002 off so that area is fine and the block was checked when I orginally put the motor in so that should be fine since it's never been overheated. So it all comes down to getting it cleaned off and smooth. Ok, as to the stone, what exactly are you talking about? I don't want to mess anything up. I just want a smooth surface so I can get a good seal.

 

[Big Woo]

I generally use a scraper or putty knif to remove any graphite rements, then use 2" X 6" mediun fine sharping type stone to clean and smooth the deck surface. You could also use a piece of fine sand paper with a sanding block. Just use caution and go easy.

 

[Xit40]

Ok thanks a lot. That's pretty much what I figured. I don't really want to take anything off just make sure it's pretty smooth and get rid of any small imperfections.