Hi

Because I use 98oct I was thinking to use 12.5 compression pistons with toda cams V2. The shop which is making the pistons told me that I can use any cam, but I should clay the short block to measure how much room there is between the valves and the pistons with the cams at maximum lift.

What means clay? So I am buying a set of piston that will match any cams, but I need to measure if there is any room?, so there is a possibility that I can not use the cams?


I am totally confused


any help or explication will be very useful

Juan

 

The issue he is trying to describe to you is having to large of a lift on your cam. so you should put clay on the piston heads and then rotate that motor by hand and then check for marks on the clay. if there is a mark on the clay your cam is too large and is causing the valves to make contact with the pistons. A simple fix to this is a smaller lift cam or fly cut pistons.

 

If you are using adjustable pulleys, setup your motor without any pistons/rods and only 1 cylinders of valves to set the cam phasing correctly.

The with 1 piston in place install the valves with lightweight springs. This allows you to turn over the motor slowly while pressing down on the valves to check clearance.

See my post on my F24C build for pictures when I checked my clearances.

https://www.s2ki.com/forums/index.php?showtopic=692401

It is possible to do this by putting plasticine on the tops of the pistons, turning the engine over then removing the head to check. I find using checker springs is much quicker and allows you to make adjustments to your cam pulleys to overcome a clearance problem without pulling the head and rocker assembly off the motor a dozen times.