I plan on replacing my valve seals without pulling the heads. I need to buy one of the compressed air fittings that goes in the plug hole and allows the compressed air to hold the valve up while I remove the springs and replace the valve seals.

Does anyone know where I can buy this air fitting?

 

I've used a spark plug Non-fouler connected to a rubber hose and it worked great.

 

I never use anything. Just turn the engine till the piston is up on that cylinder.

 

That's how I did it.

 

NAPA sells them. That's where I got mine. Some compression testers use a hose that is this adapter with a male air fitting, the gauge has a female fitting.

 

What if you put that thing on there and put air pressure on it. The piston will naturally go to the bottom. And you accidentally unseat that valve and it drops in there?

 

Thats a good point Wayne and that would suck. I've never had a problem using air, I just did a V-12 this way, not something you want to pull a head on. You definately don't want to use a cheap air fitting or hose that could snap either.

I make sure the piston is already at the bottom so that nothing spins around when you are doing this job. With the piston at the bottom, cylinder pressurized, the valves will stay up, even if you manage to knock it a little off seat it should get pushed right back up.

Using the formual Force=Pressure x Area, use 40psi x the area of a 2.02valve will result in a force of 128 pounds on that valve face and 80pounds on a 1.6 inch valve and 502 pounds on that piston.

You can do it old school and stuff a thin rope in the spark plug hole too.

 

done it that way a couple times myself.

 

I did it 2 weeks ago. I just put each piston in its TDC. I simply marked the distributor housing for each firing position then I removed the the cap and just watched the rotor pointing to each piston's TDC.

 

Compressed air just seems like a lot less hassle if, of course, you have a compressor.

 

I used an old bungee cord. It worked perfect. Checkout post http://forums.corvetteforum.com/show....php?t=1897992 It includes a link to some pics...

 

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.

 

Thats EXACTLY what I did, I was able to finish the whole thing in no time. Plus make sure that you warm your engine just before you replace the seals, so you can set the lifters correctly.

 

I put a little rope in the cylinder and bring it up to TDC. Works perfectly every time as long as you don't have some really heavy duty valve springs...

 

good info guys,

 

If your engine rolls over with compressed air, it's a whole lot looser than anything I ever messed with
Steve's directions are great, follow those and you should be fine. Make sure your the parting line between the locks runs parallel to the crank centerline, not perpendicular. I've had more than one head builder tell me that.

 

That's all we ever did, use a nylong rope and brong the piston up, pushing the rope up to the valve, holding it in place.