I'm wondering if the valves rotate under tension while the motor is running. I had a leaky intake valve, turned it 180 degrees and now it's tightly sealing. When I put that head back in use will that valve possibly rotate in relation to the valve seat?

Thanks

Lapping that valve may fix your issue.

Thank you Sir!  After seeing that, I'm guessing they do. 

 

I tried lapping it a couple of times yesterday.  It helped, I do believe.  I'm going to try a more aggressive grit now.

Thank you Sir!  After seeing that, I'm guessing they do. 

 

I tried lapping it a couple of times yesterday.  It helped, I do believe.  I'm going to try a more aggressive grit now.

 

I'd say your inference is correct! Good luck!

With the valve springs installed the seal will be tighter.  Even hard materials compress and deform a small amount.

 

The valve seat does more than just seal, it also transfers heat.  The width and angle of the sealing area is a balance between those two things, determined after many hours of testing and years of usage.  I would shoot for a proper contact area width after lapping and not worry too much about a complete air seal with no springs installed.  Just saying, it's easy to get drawn in to things that might not really matter much.

I can put a pen light down the runner and see light. It could be a bent valve but I'm going to lap the crap out of that little baby first.

The springs are on nice and tight too. My thinking is what someone brought to my attention, maybe you?, about the cylinders compression with a leaking valve.

Edited August 17, 20159 yr by siteunseen

 The easiest way of testing for valve leakage after lapping is to install the springs, tip the head so the ports are up and pour solvent into the ports. Then watcht the combustion chamber for leaks. Works great!

Thanks Mark.  I've heard isopropyl alcohol, kerosene or mineral spirits.  I will try this but honestly I didn't do the lapping properly.  I only did a rough cut until the sound changed which in hindsight was just the grit wearing down.  I'm not in any hurry especially now that the weather has finally loosened it's grip down here so I just picked up another set of valve seals and will do the lapping the right way then reassemble.  I found some great spring compressors that make it soooo much easier it's almost fun.