im goin to an all motor ls/vtec with a Type-R head im goin to use ls crank, ls rods, with 12.1 compression i want to know if the pistons are goin to hit the the Type R head

 

If the deck height is stock along with an "un-milled" head you should be fine. Clay the motor and check clearances. The pistons won't come in contact with the head, but the valves (depending on cams, valves, etc).

 

so as long as the head is not shave down i should be fine then

 

Depends what pistons do you plan on using and their compression height. Also Piston to deck height and gasket thickness play a role...
OEM P30 and P73 pistons are popular choices.

 

well i was goin to the cp piston 12.5.1 81mm

 

If they have the same compression height, you should be OK. As stated above, you will wanna check piston to valve/valve to valve clearances with any build using large dome pistons...

Any reason you dont wanna use OEM cast pistons?

 

o ok then

i just want to to everything rite i dont want to use OEM

 

^ But everything can be right AND oem?? my ls/vtec block is oem internals making a static compression of 12:4:1 and it came out just fine.

 

yo your ls/vtec block everything was fine with it rite an it did not hit your head at all

 

you still want to clay the motor, even if you are 99% sure its within clearance..

 

No sir. Just have to make sure and be tedious with the clearances and all. Be very careful how and who puts it all together. Definitely something you don't wanna skimp on...

 

It would be dumb to just "slap" your motor together and hope for the best. Check the FAQ's on how to clay a motor.