Need to replace the valve stem seals, and wanting to know what is the min.... and max... air pressure that is needed for the combustion chamber? Don't want to drop a valve, and not wanting to blow out any seals.....Thanks you, Hans

 

I used about 20-30 psi and also put the piston to the top just in case the valve dropped. With the piston at the top you can adjust the valves
when you put it back together before moving on to the next cylinder.

 

http://www.corvette-101.com/valvestem.htm

 

Done it multiple times and never used a compressor. Just put the piston at TDC for each cylinder in turn and the most a valve can drop is about 1/2". I also push a little rope in through the spark plug hole.

Here is one post I did about the job:
http://forums.corvetteforum.com/showthread.php?t=947140

OK, here are my directions from an old post:
Here is my method. No compressor required and I can do 16 seals in 3 hours.

1. You need a small magnet, hammer, wheel grease, spring compressor (I use the cheap bar type), rope, a balancer that is marked every 90 degrees plus wrenches, etc.
2. Remove spark plugs.
3. Rotate balancer (I use the bolt) till you get to the 0 degree TDC mark.
4. Ensure that you are on #1 TDC on firing stroke by pulling the distributor cap. Rotor pointing close to #1? Good. If it is pointing to #6. If not rotate crank 360 degrees and recheck.
5. I feed a little rope into the cylinder through the spark plug hole but it is not required since the piston is at TDC.
6. We are now ready to replace the springs/seals on #1.
7. Remove rocker arms and pushrods. I then do each spring in turn.
8. Tap spring retainer with hammer to help "break" friction.
9. Compress spring and remove the keepers using the magnet.
10. You can now replace the seals and springs.
11. Compress spring and retainer assembly and reinstall the keepers. A little grease on the inside of the keepers will help them stick to the valve stem when doing this.
12. Reinstall pushrods and rockers.
13. Since the piston is at TDC on the firing stroke, both valves are closed and the cam lifters will be on the base circle of the cam. This means that you can relash the valves at this time for that cylinder.
14. Remove rope and rotate crank 90 degrees.
15. Repeat for next cylinder IN FIRING ORDER.

The beauty of this method is that with the piston at TDC, the valve cannot drop down more than 1/2" and will not fall into the cylinder bore. Also, block the oil drainback holes in the heads. I use those thick blue paper towels so I don't get lint in the oil.

 

blowing seals? You arent' going to introduce ANY WHERE NEAR the amount of cylinder pressure that combustion creates! LOL

Even a small compressor can do the job.

 

I used the method that SteveG75 described and it worked perfectly!! I used an old bungie cord instead of rope. The 1st. one may be a bit time consuming but once you get the hang of it, it's a piece of cake. Pictures are worth a 1000 words. Here's a link with photo I snapped during my seal replacement.

http://picasaweb.google.com/Walllpar...temReplacement

 

Nice job on the write up Steve. Have you submitted this as one of the tech articles for the C3 Tech? I think this would be a great one.

Bytor, thanks for posting the pics. That should help very nicely.

 

[QUOTE=SteveG75;1563343593]Done it multiple times and never used a compressor. Just put the piston at TDC for each cylinder in turn and the most a valve can drop is about 1/2". I also push a little rope in through the spark plug hole.


OK, I give. This is killing me: what the hell does pushing a little rope in thru the spark plug hole mean, holey cow I don't get that at all..............

 

You just bring the piston about halfway up to TDC and then feed some nice clean rope (I prefer to use nylon) into the cylinder through the spark plug hole. Bring the piston up the rest of the way (by hand with a breaker bar) and the rope will jam into the combustion chamber preventing the valves from dropping when you remove the spring retainers and springs.

When you're done and have reinstalled the springs and retainers, just back the piston down and remove the rope. Works great and lasts a long time... I used this method many times as a youngster, before acquiring too many tools... according to the wife.

Good luck... GUSTO