i have a 91 accord and i plan on shaving the head a little to get a little more compression....what is the most i could take off without worrying about the valves hitting the pistons...i've heard of people taking like .040 off but that worries me a little

 

FYI, it's called 'decking'.

You should talk to a machine shop that deals with a lot of Hondas. They should know how much would be safe.

Personally, that seems like a jerry-rig way to raise compression. Once you do that, you can never go back without replacing the head. Why not just get new pistons? That way you still have the ability to change things in the future.

Also realize that when you raise compression, you're putting more stress on the internals and the head gasket. You should upgrade these parts if you plan to raise it as much as you're talking.

JMO.

 

By Decking or Milling the head that much your not gonna get that much hp out of it, especially on an engine as old as yours is. Its not gonna be worth the effort. Just do an engine swap if your gonna spend that kind of $$ to get that little hp out of it. I agree with westcoaststyle, you can get 3CR points out of pistions with less effort than having to mill or deck the head and worry about the valves hitting the pistons, and the engine could use a rebuild im sure.

 

Decking just shortens the life of you engine, as just about anything done to it. My friend got .032" taken off and there is no difference whatsoever, other than it smoking a little more now.

 

im a senior in high school and i take a machine tool class for 3 hours a day...my dad is a machinist so i have grown up with it and i know a little about it...i also rebuild cylinder heads in my spare time but there is not a lot of imports around so i mainly work on V-8's..i have decked several blocks and heads but im still not really familiar with 4 cylinders...thats why i wasn't sure about the clearance...i also recently bought another accord with an engine with considerably less miles so i always have a back up motor....i'm going to order a thicker gasket so i thought since it won't cost me anything to "deck" the head myself it will make up for the thicker gasket.

 

i agree that decking shortens the life of your motor....if you don't replace seals,bearings,and rings...my guess at why your friends car smokes more now is because he didn't replace the worn rings...or he didn't replace the old valve seals.

 

If you're decking the head to make up for a thicker headgasket that's reasonable. If you're concerned about sealing I would be more inclined to put some head studs in the block and run a standard Honda headgasket rather than some thicker one. Mill the mounting surface of the head just enough to get a good seal and leave it at that.

One thing which you probably overlooked since you've been dealing with what I'm guessing are pushrod motors, is that if you shave too much off the head you'll actually mess with the cam timing since the gears get moved closer to the crank pulley.

But hey this is a learning experience right?! Go ahead and shave the sucker if you've got a spare motor lying around. The stock headgasket is 0.029" thick. Cometic makes gaskets up to 0.078" thick although I'm not positive you can get one for the F22 you've got. I know they have one for the H22. Anyway if you can find a gasket that thick it'll give you enough extra height that you'll be able to shave plenty off that head and still not be overly concerned about whacking a valve with a piston.

 

thanks for pointing out some things i overlooked

 

New to this board but not to engines. If you mill your head you will retard the cam timing and your increased compression will not be noticable. If you have an adjustable cam sprocket you can advance the cam to get back to a decent torque curve.

 

Good info! Thanks for pointing that out.