Larger pistons vs stock head gasket
 

Hey guys, I am starting my first build and have come across a question I can't find an exact answer to. I am going to run 83.5 mm supertech pistons and have had my cylinders bored out to match. Will a OEM head gasket cause any problems? My pistons shouldn't be over the deck as I haven't had material milled off. Additionally, I have read mixed information that you shouldn't have to worry about the head gasket unless your pistons are more than 1 mm over stock (mine are only half a mm.)

you'll be fine

I went up a couple sizes and used a regular gasket 18 is right.

Also food for thought. If you have an 01+ motor you should get a 94-00 head gasket and do a reroute. If you have no clue what I'm talking about happy reading.

I appreciate the feedback, it's been helpful. I'm running a 95 block and head. I still plan on doing a coolant reroute 100%, although I'm leaning more towards the diy option. I've seen the kits on 949 for example but they look way too expensive for what it is in my opinion. Not trying cut any corners though, any thoughts?

OEM gasket should be fine, I'm running 84mm pistons on a stock gasket and all the boost with no problems. I have a DIY reroute, many do, and they work great when done right and are cheaper as you already know.

I also did DIY. I hope I don't have to change my thermostat for a while though lol... The kit makes serviceability better but that's it.

I have an 84mm bore and have unshrouded the valves which are over sized. If I used a stock gasket there would have been just the slightest "ridge" in the areas where the valves were unshrouded.

The max limit of the unshrouding was determined by bolting the head to a block with no crank rods or pistons, turning the motor upside down and marking the edge of the bore with a scribe. The unshrouding work was then performed in a CNC mill.

The Cometic 84mm gasket fit perfectly.