As you guys know I'm doing a 97mm piston and well I need a custom made gasket. My question is about the thickness. Lancer told me there was a discussion about it but I can't find it. Moto is going with a .032" and well I personally was thinking to go with a .042" or even a .050" .

I want to make sure maybe there is someone who remember the threat and can let me know. I want to avoid the worst!! Piston hitting the head and boom! There goes the crankcase'! :'(

When I chose mine, I put calipers on the stock head gasket and then, just to be safe, went a little bit thicker, even though that might negate some of purpose of a higher compression piston. For what it's worth, with everything bolted back together, and turning the crank manually, nothing is hitting -- and that's with the stage 1 cam.

 
Uh oh ....


Son of Rex, take #2 .......


Daddy ..... Daddy .....  I boo-boo'd my little tulips and it hurts so bad ....

Remember, the new piston top has cutouts for valve clearance, whereas the stock piston is essentially flat.

No, I haven't started my engine yet. I'm still messing around with electrical and other things.

Valve float can happen with some engines at top RPM, where things get moving so fast that the valve springs can't pull the valves closed fast enough before the piston reaches TDC again.  But since the valves aren't sealing completely, the engine is losing power anyway, which keeps it from revving higher. With a thumper, the reciprocating mass makes it hard to rev it so high. Unless you're going to be revving it to the max all the time, it's way down on the list of things to worry about.

It's not that the copper compresses, rather it conforms to the tiny irregularities of the machined surfaces.

Was it done for a wiseco piston with a lancer cam? 1 or 2?

I've built many engines over the years, and when I build one where I am unsure of the clearance due to a piston or cam change, I check the clearance using modeling clay.

I put a layer of clay on top of the piston, spray some PAM on the combustion chamber & install the head & cam, adjust the valve clearance to zero lash. Then I slowly rotate the crankshaft at least 2 times, then pull the head back off & measure the thickness of the clay where the valves compressed it. This will give you the exact clearance you have between the piston & valve & may save you $$$$.

Your total clearance will be the amount you measured plus your valve lash. If you do not have enough clearance, any good machine shop can cut valve reliefs deeper in your piston.

I have a 2.3L ford engine with the head shaved .110 & the block has been milled for zero deck height on the pistons. It also has an adjustable cam timing 'gear' so I can retard or advance the cam timing. When it was built, I checked clearance at full advance & retard so I wouldn't have to worry about any adjustments made at the track causing a problem. This is an engine that turns 8 grand on the track & cost several thousand $$$ to build so I don't take chances on something I can check giving me a problem. I've seen what happens when someone didn't bother to check & it ain't pretty. :'(

 
Little factoid about stage 2 cams ....

They pull strong at upper rpms, right up until you hear the flutter sound of floating tulips that ends the power run up and signals you need the next shift.

You WILL float your valves with a stage 2 cam.   Just make sure you have enough room over your piston or you too will be cuddling your little monster while it rocks back and forth clutching its crotch moaning and crying in pain.  

Banging your little tulips hurts BAD ..... even when you are a monster.