Step 2 V-Cam with 9:1 CP pistons ?

[McGarryR32]

Hi folks, currently in the middle of a V-cam build and was under the impression that it required pistons with valve recesses. 
Talking to supplier there was miscommunication and I ended up ordering 9:1 CP pistons thinking that they had recesses. now I’m being told there’s gonna be a 2+month wait for customs or HKS step 2 pistons and really want to get the car out for summer. (in N.Ireland lead times are insane thanks brexit)

Can anyone confirm if it can be done ?  came across a post here where somebody said they did but I can’t for the life of me find it. 

  

 

 

[Piggaz]

Only way to know for sure is to measure it up. There are soooooo many variables here.

- has the block been decked?

- has the head been decked?

- head gasket thickness?

You could put the valve recesses into the pistons yourself.

[joshuaho96]

4 hours ago, McGarryR32 said:

Hi folks, currently in the middle of a V-cam build and was under the impression that it required pistons with valve recesses. 
Talking to supplier there was miscommunication and I ended up ordering 9:1 CP pistons thinking that they had recesses. now I’m being told there’s gonna be a 2+month wait for customs or HKS step 2 pistons and really want to get the car out for summer. (in N.Ireland lead times are insane thanks brexit)

Can anyone confirm if it can be done ?  came across a post here where somebody said they did but I can’t for the life of me find it. 

  

 

 

If they don't have a recess it's basically guaranteed you need to have the valve recession machined into the pistons. The extra 20 degrees of cam advance increases the valve lift that occurs at TDC between the exhaust and intake phase. UP Garage in the USA does this to stock cast pistons so you can absolutely do it on your CP pistons too. The precise amount of relief you need to cut is hard for me to say but an experienced engine builder should be able to figure it out when taking measurements.

[GTSBoy]

1 hour ago, joshuaho96 said:

when taking measurements

This is the key statement again. There is no point in trying to pick a number to make the flycuts because you're as likely to get it wrong too close as wrong too loose and one will stop your assembly effort as bad as waiting to measure anyway, and the other is a waste.