[bszopi]

I've updated the CR Calculator to include the calculated quench distance for the inputted values. This will help people determine if they will have interference issues or not when building a custom setup. This MAY NOT guarantee that you will not have valve clearance issues, as that is depends on the lift of the cam. If I can figure out how to calculate that (accurately), then I will incorporate that into the equation as well.

[ForcedFirebird]

To calculate weather or not there would be valve clearance, you would need the user to enter the cam profile as well right?

[bszopi]

Yeah, you would need to know cam lift as well as rocker ratio. Adding those inputs is the easy part, and most people building an engine would have those numbers available. You would also want valve size as an input option, in case the person increased the valve size. The hard part comes when trying to do the math, based a valve size, lift, and then the angle of the canted valves as well as their "stock" location in the head as measured from the surface of the head. I think it could be done, but figuring out exactly how to calculate it, and do it accurately is where the problem lies.

[ForcedFirebird]

You could figure clearance for stock valves and cams to pull your values. You could measure this by seeing how much the valves moves before hitting a table or other surface. Using a bare head with no springs on a piece of granite would work perfect. Then you can add the values of the head gaskets and piston deck height.


Also I noticed on the calculator that the 3.4 has a positive deck value and the 3x00's have a negative?

[bszopi]

That's the info I have as far as the piston deck goes. If you can prove it otherwise, let me know and I'll get everything up to date.

I never thought about measuring the movement of the valve itself. That's an excellent idea. I was more thinking of how to measure from the center of the valve to the deck, all the while being accurate. Maybe I can get Ben to take some of the heads he has and get various movement distances for me. Then I just need to figure out how much the valves are canted.

[ForcedFirebird]

Originally Posted by bszopi

That's the info I have as far as the piston deck goes. If you can prove it otherwise, let me know and I'll get everything up to date.

I never thought about measuring the movement of the valve itself. That's an excellent idea. I was more thinking of how to measure from the center of the valve to the deck, all the while being accurate. Maybe I can get Ben to take some of the heads he has and get various movement distances for me. Then I just need to figure out how much the valves are canted.

Even with the canted valves, you should still be extremely close. If you wanted to get crazy with the math, you could use the angle of the valve and use trig to calculate the movement of the valve increase lol. Although, for intensive purposes, it will be close if you just add the lift to the stock numbers.

[WrathOfSocrus]

Originally Posted by ForcedFirebird

You could figure clearance for stock valves and cams to pull your values. You could measure this by seeing how much the valves moves before hitting a table or other surface. Using a bare head with no springs on a piece of granite would work perfect. Then you can add the values of the head gaskets and piston deck height.


Also I noticed on the calculator that the 3.4 has a positive deck value and the 3x00's have a negative?

The piston to deck clearance is how far the piston is from the deck surface. Since the 3x00 motors go above the deck the clearance is a negative number, protruding from the deck. At least that is how i thought it went.

I personally would measure it myself, especially with any after market pistons.

[bszopi]

Well, as I stated, I'd like to have a baseline to go from, and then be able to use the calculator to also figure out clearances if someone put in larger valves. A larger valve would case the edge to hit the deck sooner, but to know how much sooner, you would have to know the canted angle to be able to do the trig (or geometry?).

And yes, a negative value means the piston is protruding from the block.

[ForcedFirebird]

Iron head pistons are proud by the .0095" you have listed for them. Measured them and the 3500's to be .010" several times

Brad, yeah I said trigonometry because you need to use sine, cosine, and tangent lol. We use it all the time in machining.

[SappySE107]

dynomation gives me valve lift vs crank position:P I avoid math if I can have it done for me As far as measuring, I can do .050 lift increments and measure the valves postion. That might help something, i dunno.