possible for timing to be 180 degrees off?  By  mattwg (Read 11,493 times)

180 degress? Actually yes it's possible, but doesn't matter. Most modern distributor-less electronic ignition systems fire on every stroke. The trigger coil is attached to the crank via the rotor and doesn't know one rotation from the next. The piston goes up, the piston goes down, it just sends the signal every time. I know it seems odd but firing the spark on the exhaust stroke doesn't bother anything. It's just simpler to build it that way. My Subaru is the same way.

The cam shaft is geared via the chain so that two turns of the crankshaft equals one turn of the cam shaft. That's what determines the which stroke you're on. If the cam timing is off one tooth either way it should still run, just maybe not as well as it should. The timing marks could be off just a hair due to manufacturing tolerances. (You could try slipping the gear a tooth either way to see if it lines up better or worse.) Get the timing really wrong and the valves will be down when the piston comes up and bad thngs start to happen. (I am making the bold assumption that you are lining up the "T" mark on the crankshaft rotor with the index mark on the case while you are checking the cam gear alignment.)

Valve adjustment could also be a factor. The valve clearance will ultimately affect when the valve comes in contact with the cam lobe and the height and duraton of the valve lift. Too little clearance and the valves won't close completely and or don't rest on the head long enough to dissipate the heat build up. Too much clearance and they bang around and are noisy. You did check that the new parts were same dimensions as the old? Have you done any sort of compression test to see that the new valves are seating correctly?

i suppose I have to ask; Did you change anything else or take anything else apart during this valve change?

Coincidentally I have my Lance Milan (same as the Evo V9) in pieces on the bench at the moment (waiting for parts) So I have reference material

Did you lap the valves and do a leak test before setting putting the head back on the engine? If the valves do not seal well then you won't get good enough intake draw or compression to start. Valves are only part of the equasion and putting hard valves on soft seats will leave you with seat wear with the vavle gap now closing up as the hard valves sink into the softer valve seats.

Is it possible that you had the engine a bottom dead center instead of top dead center when you set the timing chain?

Sounds like you did everything right. Shouldn't matter which way up the valve springs go. Let us know what you find out.

Ah Chinese Engineering denying the laws if physics for 5000 years