Replacing head gasket...what do you tell the machine shop?

[90CherryTSI]

to do? I don't plan on swapping out anything internal yet, so do they just pressure test, and make sure it's flat? Shave it down 2/1000's of a mm? Just dip it and clean it? Wait they can't dip our heads can they? They just pressure test and clean them? Should they already know what to do? I thought they could shave them down some tiny amount for some power related gain, but I can't remember...?

 

[1gE.T.]

If they know what they are doing they will tell you everything you need to know. Just tell then what happend and that you need it rebuilt.

They will probly replace the valve stem seals,hot tank it, check and reseat the valves, and check the deck on it.

 

[90CherryTSI]

the three angle valve job or something? shaving it down?

 

[1gE.T.]

Yea, I think 3 angle is standard on most valve jobs. At least thats what people say. It is possilbe that you might need the head shaved down a little to make a level mating surface to the block.

 

[90CherryTSI]

what exactly they do? change the valve angles by 3 degrees?

 

[1gE.T.]

As far as I know on angle valve jobs they actually put more angles on the eges of the valves. The more angles you have the more power you get becuase it changes the velocity of the air going into the chamber.

 

[Suparata]

The three angles are on the valve seat http://www.engintecs.com/gallery/album11/Reconditioned .The one that actually contact the face of the valve is close to 45^ and the other two are usually 30^ and 60^ and they narrow the width of the 45^ one locating it in the correct place on the valve face.
Read these for more info
http://www.dsmtuners.com/forums/showthread.php?s=&threadid=98871
http://www.dsmtuners.com/forums/showthread.php?s=&threadid=99898
Just tell your machinist to check your head thoroughly and let you know what it needs .
Mitch.

 

[90CherryTSI]

that helps a ton, thanks!