piston valve clearance

[flyby]

I broke my exhaust cam. im thinking a broken exhaust cam will not harm the pistons because the valves are fully open at tdc anyway. On the intake side though there should be issues. what u think?

 

[Commuta_Busa]

I'm not sure what exactly your trying to say. Depending on the cycle the ex valves should be closed at TDC (compression stroke). I would pull the head if I broke a cam. How did it break? ???

 

[flyby]

the exhaust valves are fully open at tdc on the exhaust stroke, so i don't see how they could possibly hit the pistons during any part of the stroke cycle. the intake cam would definitely be a problem. i did a leak down test with both cams out, and all the cylinders were the same with no air coming out the throttle bodies or muffler that i could hear. should b just fine.
i installed a new cam chain, and i think the manual adjuster was too tight. the motor ran fine for over an hour, and then just broke. wasn't even reving it.
so im in the market for an intake cam for the exhaust side, and adjustable sprockets. thanx,

 

[Commuta_Busa]

The leak down test answered your own question

Can you tell me more about the cam damage? Any pics? Is it completely broken into two pieces? Where's the break or crack? Just curious...

 

[Mr Bogus]

you can bend valves if any cam breaks and the motor is spinning over..

the chase/follow clearances only apply to valve timing and not broken cam with valves that may be stuck wide open.. (fully open is pretty rare IME.. they will usually find an in-between when the cam centers on a couple ramps)

the exhaust valves are fully open at tdc on the exhaust stroke, so i don't see how they could possibly hit the pistons during any part of the stroke cycle. the intake cam would definitely be a problem. i did a leak down test with both cams out, and all the cylinders were the same with no air coming out the throttle bodies or muffler that i could hear. should b just fine.
i installed a new cam chain, and i think the manual adjuster was too tight. the motor ran fine for over an hour, and then just broke. wasn't even reving it.
so im in the market for an intake cam for the exhaust side, and adjustable sprockets. thanx,

I would be checking cam journals for line bore and lubrication... camshafts do not "just break" normally... what percentage of leak were on the cylinders?