Going to my uncle's next weekend to replace a couple of broke valve springs. Does anyone know the size of socket I need to turn the motor over by hand to get the cylinder at the top.

I'm asking because he has no tools and it's a 2hr drive.

Thanks in advance

 

Might be easier to rig up an adapter to pull the spark plug and hook an air compressor up, and pressurize the piston chamber. I've done this before and it works fairly well at keeping the valve up.

 

I still need to turn the motor by hand to get there cylinder I'm working on to top dead center.

 

Except you don't. You just need the valves to be closed. Compressed air doesn't care where the cylinder is in the rotation, just that the valves are closed.

And once you take the rocker arms off, it doesn't matter where anything is at - you'll need to pull the valve with the broken spring up to seal the chamber, but after that the compressed air will keep the valve up.

 

That makes total sense.. Thanks for that

 

Maybe I'm overthinking this, when I take the rocker arm off won't the spring be decompressed (valve pulled up) then injecting air into the cylinder at this point will keep it up. I can't pull it up higher with the spring on it, if I take the spring off to pull it up it will drop unless the cylinder is pressurized.

 

That is correct, with the cylinder pressurized the valve shouldn't drop unless you push it down or you've got a bad compression leak, in which case you'll have bigger issues. So be careful but it should work just fine.

I know you likely don't have a place to do it, and it's a LOT more involved and expensive, but valve springs are SO much easier done on a bench with the head off the motor.

I have also seen people tie a piece of string (actual string or fishing line will work) around the valve stem just in case it drops - it will help you pull it back up if it goes down into the guide.

 

Ok. Thanks. But I still want to take a socket with me just in case.

Anyone know the size of socket needed to turn the engine... Please...

 

I just replaced a valve spring on my 6.2L, I believe it was a 15/16 or 1" socket that I used to roll the engine over. Can't remember for sure but I think it was somewhere around that size. I took the gauge off my compression tester, got an adapter to hook a male air fitting into the gauge port of the compression tester, pulled the schrader valve out of the compression tester and hooked the compression test hose onto the quick coupler, put it in the lower sparkplug hole and hooked it up to shop air. I did this with the engine at TDC on the cylinder with the broken spring just in case something failed with the air supply I didn't want to lose the valve. There is absolutely no reason why you need to pull the head, I bought a Maddox overhead valve spring compressor from harbor freight $12, just be careful not to drop anything down the cylinder head when the valve cover is off. I used a magnet to pull the valve keepers off the valve, I replaced the spring, valve stem seal, and valve cover gasket. Also watch when reinstalling the rocker shaft, I raked 3 of the arm ends against their valve springs breaking the plastic retainers which keep the rollers on and had to replace 3 rocker arms.