One, what is the max lift one can run on a 389 or 400 while still maintaining non-interference. That is to say, the valve will not touch the piston even if the valve is at max lift and the piston is at top dead center. Second, how much horsepower can a 389 or 400 produce with a given amount of air. Example 1969 Camaro Z/28 RS according to American Cars The Automobiles That Made America, Amber books. 302 / 2 =151 x 5,800rpm (peak horsepower) = 875800 cu. in. per minute / 12^3 = 506.8 cubic feet per minute / 290 (horsepower) = 1.747 cubic feet per minute per horsepower or 302cu in = 4.948L / 2 = 2.474L x 5,800rpm = 14349Lpm / 290bhp = 49.48L/HP
Hmmmm...the valve is at max lift roughly during the middle of the piston's stroke, so I don't really understand the question.
I run a dual pattern solid roller on my 195 4 cylinder, int. .620+ / exh. .630+ (can't remember exactly, cam card is long gone). The head is a late 60's big valve head and the pistons are forged Ross with minimal/stock valve relief. Not a lot of valve clearance, but it's in a safe range. I'm not sure I understand your second question. There are too many variables to come up with a concrete number. Compared to the Chevy 302, I would say it's less everything else being equal/constant. Stock Pontiac heads aren't as efficient.
Best bet is go to Pontiac site "Pontiac Years forum" for any information you need.There are some of us that run Pontiacs on H.A.M.B but PY is the place for Pontiac.
Stan, if you have valve to piston contact at TDC, you have a SERIOUS problem as like that shouldn't happen. On the intake stroke, the intake valve is chasing the piston, and on the exhaust stroke the piston is chasing the exhaust valve. The possibility of these events resulting in collision happen before and after TDC. Hope that helps a bit with your understanding theory. TDC.
To take it a step further, if you machined adequate valve to piston clearance at TDC, chances are the valve will still contact the piston at max lift, BECAUSE of the included angle of the valve. If the valve were in line with the cylinder bore, your theory would be true. Draw 2 pictures, each a side view picture of a piston and valve at a angle above it. Now extend the line of site for the valve through the piston dome. You can then see how the edge of the valve will land on the piston dome at a different location when the valve is at full lift and at TDC, as compared to the valve at full lift and down in the cylinder. This is diffrent with each engine as each design of cylinder head will each have a different included angle of the valve, that's just very basic theory now. Ever use a milling machine or drill press with a angle vise? Drill a hole, and then move the table up or down on the column, notice the hole or drill point has now moved? Same principle. Hope that helps, it gets very complicated moving further, TR
I have a 400 Pontiac with stock pistons, 670 heads Edelbrock troker cam and use 1.65 rocker arms with no clearence issues. Don't know how much HP it makes but it kicks *** in a '35 Chevy pick up.
As far as I know, the only way for a valve to be full open while the piston is a tdc is for the camshaft to be horribly out of synch. Imagine the timing chain gives out, if the valves cannot touch the piston under any cir***stances repairs should be very minor. Compare that to my uncles '77 Lotus Esprit, if the timing belt slips two teeth the engine starts snapping of valves.
Stanisslow; I was feeling sorry for you being beaten up a bit here until you tried to answer your own question!????
This is just childish horse poopy. To the O/P, ask anyone here, I was trying to help you, nothing more. I enjoy helping people here I feel deserve some help, nothing more. PLEASE, PLEASE dont EVER think I was trying to make fun of you, belittle you, or GOD forbid beat you up. I have a habit of explaining things in a simple easy to understand fashion, nothing more. I can go technical if you want- fluid dynamics, physics, adiabatic efficiency, you name it if it's involved in engine building. If the O/P thought I was beating him up, please accept my apology, and I hope you understand. Engine Pro brought up a good point of the period of overlap, I simply didnt want to throw to much at you, I dont know your level of expertise. In 30 years of building race engines, I never had a instance where after fly cutting valve pockets in a set of pistons, at the positions I stated in my first post, you then had interference with valve/piston during overlap. So I simply ommitted that. I'm speaking of race engines with intake valves almost 2 1/2" in diameter, lifting off thier seats almost a 1 and 1/2", and 17:1 compression. Thank you again for listening, TR
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