Trying to replace the valve stem seals on a '82 Gran Fury - LA 318 engine in place. I'm having a heck of a time trying to compress the springs enough to get the keepers free- anyone know of a good valve spring compressor tool that works well with this engine?

What are you using now?
Are they single coil with a damper?

Did you break each set of keepers loose with a socket and hammer after you pressurized the cylinder?

The springs do have dampeners - yes I rap on the spring retainer to crack loose the keepers. Currently using a hand tightened compressor that grabs the spring itself - the arms only go about 2/3 of the way down so it only compresses part of the spring, making it very difficult to get the keepers out

Using that type Ive changed lots of springs,The trick is to get the keepers loose then i tilt the spring and rotate them.Some types compress it more than others.Try doing a set on old 354 57 heads.real pain in the butt.My kid bought the Mancini tool that has the lever arm and bolts down on the shaft pedestals.Rocky

Yup that little compressor leaves a little to be desired. I'm pretty sure it's the first compressor I ever bought and now haven't used it for 25 years I bet, still in my tool box. But I do think it should work OK on a stock 318 spring, may have to twist the compressor onto the spring to get maximum bite,compression? But like I said it's been years since I have used mine.

One can be made real easy with shaft rockers,I made one for Brad hemi head long time ago, still have it somewhere.
Picture of my compressors at home, have more at work in my race shop. Might have one for a rocker shaft head, I have to look when I got back to work tonight.

The little black tool on the lower left is a valve spring tester designed to be used with a torque wrench.

I too have used that winder type over the years and worse frequent use of it was around 1995 for recalls on the vortec 4.3 engines, that were tight on access. I love it when the tool jumps off when almost cranked enough to get locks off. The pocket screwdriver with magnet is your friend.

thanks for the input - I ordered the proform tool