Problem removing inner valve springs
You cannot figure it like that. You have to figure based on WHERE the piston is in the bore. You have more square inches at BDC, than TDC, get it? It's three dimensional, not one.
I can so figure it like that because we are talking about injecting air at 90psi with the piston at TDC. The force will be psi x the bore area. And with the valve gear off, the force will be the same at BDC
I think we are on different pages here.
We have been talking about injecting air to help keep the valves closed for easy removal of the springs, and of course to prevent them from falling into the cylinders.... so the valve gear is on the work-bench.
90 psi on a 3.91 bore makes no difference on force on piston if it 1" away from top or 20" away from top. It's still 90 psi on a 3.91" bore. Now if you are talking reality on the piston making pressure it depends on when the intake valve closes and the stroke from that point.
that's correct
as soon as a valve, either valve opens, the pressure is going,going,gone, and the force with it.
My point was that to tame 90psi at TDC with air pressure you will need a 5ft bar and massive arms, cuz if you don't catch it right away, the piston is taking off. And when it gets to the bottom, it stops really really fast! So if you are still trying to hang onto a 20" bar at that time, I'm betting there will be a hospital trip involved.
Doing a LeakDown test,I have been taken off-guard by 30psi and a 20" bar. Yeah I let go.......
I use a lawn-mower starter rope, made of several strands of smaller cloth ropes, woven together, and no air pressure.
Compressed air is akin to a compressed coilspring, even a small amount can do a massive amount of work. I once had a big air bag that was designed to lift the car to change a flat tire. It operated off the exhaust system. It lifted the whole back of the car.
