yoteehunter

Ok so maybe having an old non pi does have a perk. When I installed and degreed my cams, there was a ton of ptv and I was using comp 268H cams. Non pi stage 2's if you will, and i had tons of room (it wasnt even funny). Now it is a fact that the valves in a non pi head are flat on the piston facing side. It is also a fact that PI valves are cup shaped a bit. Now when you are talking .050 thousands of clearance or lesser or morer depending on what cam and set up is being used, I would think that using non pi valves in pi heads would create more clearance and allow a pi motor to run bigger cams with better ptv space. I wonder if larger non pi valves are made and if so who makes them. The only thing I am uncertain of is if the non pi valves are the same length as a pi valve. If they are then this may be a pretty cheap and easy mod for the home head porters and DIY valve job guys out there who desire more cam clearance. If some one has some valves from pi and non pi's please compare them and let me know? And for those of you who dont have a clue what Im saying here is a bad drawing to try and explain.

97targa

Never heard of anyone trying this before! Non-pi valves are smaller in diameter than pi valves! You would have to go to an aftermarket valve and I don't believe they make them as the same set-up. You can fly cut your pistons, but they have to be removed to do so! They also relieve some compression in there reducing it by a marginal amount! I believe the valve are the same length and it's merely the cam lobes that create more travel for them. However your back to my first assumption. I have heard many people using the same cams you mention 268's for PI heads to reduce PTV clearances and have had good things to say. They have to help off the line a little better but obviously interfere with higher revs

You can take those PI valves and grind the bottom area off! No I belielve your cutting some of it's face off, but you should still beable to have a 3 angle valve job after you would initiallly start with a 5 angle job! Do you get? You would essentially be grinding off 2 faces after the job. This would be easiest to assure acccurate grinding!

yoteehunter

What is the diameter of non pi valves? and what is the diameter of pi valves? I thought they were the same size???????? I could have used a large pi cam with the amount of clearance I had. I think the non pi cams work more effecientlywith low lift cams.