Need help with the math.

[rbeeson]

Hey everyone,
I am in the initial stages of mocking up my first stroker build a 2276cc. I have CB Performance (1411) Wedgeport CNC (44x37.5) fly cut to 46 cc chambers. My cam w/1:4 ratio rockers has a .581 lift. My goal is zero deck and adjust with copper gasket (0.060). I have measured and the exhaust valve has .281 in travel before it will hit the deck and I still have .300 to get to my .581 lift. A 0.060 gasket isn't going to give me what I need to clear. On the compression stroke both valves will be closed but on the exhaust stroke the exhaust valve will be open. I haven't got to the stage of clay and rotating the motor yet, just trying to get an idea in my head before I get there.
Help my inexperience, will the timing of the valve events in relation to the position of the piston give me the 0.090 to 0.100 valve to piston clearance (that is what I have found on this forum) when it is needed.
How do you all get away with high CR (smaller chambers) and high lift cams?
Am I missing something or will it all come clear when I use clay?
HELP!!!   
Reese

[tbone53]

the exhaust valve is only fully open at a single moment not during the entire exhaust stroke. the piston will be chasing it closed during that event. so you will have to clay it to find out if they are going to hit or get really close when the piston starts to reach TDC. i am by no means an expert but this is how i understand it. if wrong hopefully someone else will reply. i will be doing all of this shortly myself so if wrong i would like to find out now also.

[ALB]

Running big lift is done by cutting valve reliefs in the tops of the pistons. Mock up the motor (with rocker arms and pushrods) and put a thin layer of modelling clay (about 1/10") across the top of a piston; a little oil on the valve faces keeps the clay from sticking. Turn the motor over slowly to leave impressions in the clay; it it touches, cutting through the clay will tell you how much clearance there is. If the valve hits the piston before full lift is achieved then note the lift and factor that into the calculations.

[fiatdude]

[maui]

Put a small tootsie roll on the piston with paper on and turn over engine one full cycle then open up and take the tootsie roll off and measure how thick and that's it. I did it and works fine and you can eat it after.

[rbeeson]

Put a small tootsie roll on the piston with paper on and turn over engine one full cycle then open up and take the tootsie roll off and measure how thick and that's it. I did it and works fine and you can eat it after.

Ha Ha Ha Ha Ha Ha!!!!!!!!!!!!!!!!

THAT IS AWESOME!!!!!!!!!!

[Ohio Tom (DdK)]

I use plumber's putty.

[Dougy Dee]

I use plumber's putty.

How does it taste???