I'm in the middle of a cam install and trying to change the valve springs. I bought the adapter to pressurize the cylinder along with the Crane spring compressor. The problem I'm having is that I am losing air pressure slowly to begin with and as soon as the compressor starts, I lose all my air. and it sounds like I have blow-by going into the oil pan. Do I need a compressor with more volume? Should the piston be up or down? I have it at TDC in case the air fails so I won't lose the valve and the pressure regulator set at 70 psi but I'm paranoid about screwing something up. Any suggestions????

 

I would either use TDC or the rope method. I like the rope method better as it helps break the locks free from the valve stem. No compressor required.

 

i used the TDC method with great success...

 

im not to familiar these engines what is the rope method?

 

If you are using the compresed air method, the piston will be forced to BDC, and yes, it will leak air once it's down there.

If you have a small compressor, it will run almost steady.

 

The rope method is when you put the end of a rope into the cylinder via the spark plug hole, then bring the piston to TDC and youll feel it pinch the rope between the piston and valves. This worked great for me, you can do 2 cylinders at the same time. I think I used a 5/16 rope (Just make sure its not all falling apart/dirty).

 

thanks for the info.

 

For 45 years I've been sticking a straw down the spark plug hole so I could tell when I was getting close to TDC.

 

I left four spark plugs in the engine to maintain some resistance to moving and the piston didn't move.

If the piston is at TDC then the valves will stay up high enough to swap the springs? I guess I will pick up some rope just in case the air tool isn't cutting it.

 

******* Sweet! that is old school, if it aint broke don't fix it my friend