Max Block shave height 1.8L
 

I have grooves on the surface of the block where my headgasket sits and I am having serious trouble finding the spec on how much height I can take off of the block. The only number I have is .008" but I dont think this is enough to get past the grooves. (one specifically) How low can I safely go? If it was on the head I would just get an oversized gasket and shave it down, but I am worried about the piston needing cylinder wall... Thanks

Take it down as much as it needs to be taken down. Then when you build the motor you need to clay it to check for piston to valve/head clearances and chose a headgasket accordingly.
You will also probably need adjustable cam gears, depending on how much you take off.

^ I agree with above. If you have the clearance you can take off as much as you want. I took 0.080 off my honda block witch is an almost unheard of amount but it worked for what I was doing. On the other had being the 1.8L is a non interference motor I would assume you could take at least 0.020 off and not be in much danger but I would still clay it and check.

The service limit for the block deck on a closed deck block is going to be based on a minimum thickness for sufficient stiffness to hold a flat surface under combustion pressure. You shouldn't have any trouble decking it .020" or deeper. You will have to accommodate for lost cam timing after much more than that, though. Of course, you'll also have to check compression ratio, piston to quench pad clearance, piston to valve clearance, etc.

Not sure on 1.8, but my 1.6 the pistons were already .020 proud of the block. Be careful and take accurate measurements. I run my quench at .015" clearance.

Just get a new block for <$100?

This. Not really worth the trouble.

^

wheres the best place to get blocks fo cheap?
i need one to go underneath my 99 head :)

www.craigslist.org
Miataturbo.net
clubroadster.net
www.2ndchanceroadster.com
Local miata guy/girlz?