I am planning on changing the valve seals on my 400 while its in my truck. I have read the procedure in my Haynes Manual. but was wondering if anyone has any more info on doing this? (do's and Don'ts)....

 

Have no idea how Haynes does it, but this worked for me:

Take your compression guage fitting and rig it to your air compressor. Apply pressure to hole. This will keep valves up in holes for procedure.

Remove rocker assembly from IN and EX.

Put bolt and fulcrum from rocker assembly back on to pedastal.

Fulcrum across this point with tie rod splitter tool. (it helps to grind two indents on flats so that splitter locates on fulcrum.)

Gently depress spring only. You may have to tap the valve stem to get the retainer to free up from the spring retainer.

This does work but is very delicate procedure. Stuff can fly all over if you slip, especially upon re-assembly. As I remember, once I got all set up, it went rather smoothly. Good Luck!

 

Ecuri has a good method and works well. I like his tool choice.

However if you use the KD tool at Auto Zone for 14.95 be careful and get the arms solid in the spring before cranking it down. Also when you are done, throw it away. My son had the more expensive one break and blow apart. He was lucky. They wear out fast.

If this is your first time and you are nervous about dropping a valve then do the following.
Yea.. you can drop a valve pretty easily.. especially if the valve is burnt or the valve seat and or valve face is worn a lot. Push too hard on the valve stem and by by…
Get a pressure regulator ( $4 at harbor freight or such ) and put it between the air compressor and the compression gauge fitting. Adjust it for 3 to 4 psi. Now remove the valve stem in the end of the compression gauge fitting so it will flow free.
Turn the crank to Top Dead Center on each cylinder you are changing the seals on. Put the compression gauge fitting in the spark plug hole with the 3 to 4 psi. setting. You can adjust it up if necessary. Just not to high as an old engine will want to push the piston down.
That will be enough to hold the valves up tight and not turn over the engine.
Then if you drop a valve it won’t go out of the guide and out of sight.

28 years ago working in a garage changing valve seals I pulled a spring off a valve that was burnt. It lost seal and down it went. ( Yea I was young and didn’t realize all that noise was air rushing out the exhaust) Spent 2 hours fishing that valve up into the guide again with all kinds of home made wires. The boss just chuckled every time he walked by and then roared when he got out of sight.
After I got it back in the guide and the spring together he said “Hey it’s a burnt valve we have to pull the heads and do a valve job”
Needless to say I didn’t make book on that job….

Hope this helps..

David

 

Don't sweat the air thing! There is a MUCH better method using a length of rope pushed into the spark plug hole. No worries about dropped valves then. You can find a detailed description of the process several places and in the garage forum.

 

I remember reading about that also now, Eric. How did the rope work for you? I had concerns about getting the rope spread around neatly to hold the valves fully up in the seats. It takes a lot of spring compression to get the retainers off the stems as is. BTW, David10, had me LMAO, thanks for sharing that story.

 

Don't worry about spreading it around, Just shove about 3 feet of cotton clothesline rope down the spark plug hole leaving some hanging out. Turn the engine over to compress the rope in the combustion chamber. Jam the engine into that position so it will not turn then go after the valves to your hearts content.