hello,
i have searched for a few hours on this topic. i have a b20z2 with a stock gsr head and oem head gasket. I would like to run ctr cams and i am wondering how big of a valve relief i will need to cut, if any. i have had many mixed inputs on this topic, some say i need to cut larger valve reliefs and others say i can run these cams without cutting the reliefs. so any input would be greatly appreciated.

 

If you can't get a straight answer, try claying the piston to check the clearances.

 

you will hit the piston....

 

how much larger do the reliefs need to be made?

 

large enough to clear the valves.

 

is there any link on how to do this?

 

IDK, but I'm sure you'll need a Dremel or something similar. And also, you want I believe something like .02" extra clearance. The rod will slightly stretch at high RPMs.
An OEM head gasket is something like .03", so if you just laid 1 layer on and had exactly .00" then it would be good with 3 layers. Maybe my math is wrong, but just an idea.

 

https://honda-tech.com/forums/all-motor-naturally-aspirated-44/b20-vtec-piston-myth-1320610/

Good info.

 

thank you very much for the info! i opened up my service manual and found out the difference in gsr and type r cams.
intake cam
primary -.013
mid .019
secondary .005

exhaust cam
primary -.013
mid .025
secondary .012

thank you very much for this info it helped me alot

 

well i took off .04" off, i am going to clay the motor tonight to see if that was enough.