Okay, I decided to tackle myself replacing valve stem seals on my 70 Cleveand. In reading the manual looks pretty straight forward. Couple of questions though:

1. How much pressure do I run in cylinder hole - does not say in manual. Have a small 3 hp compessor

2. Does not say anthing about finding TDC before running pressure and compressing srping andremoving valve - I assume that is not necessary.

3. When installing valve back manual says hold valve in closed position and apply air - what doesclose position mean?

4. Manual calls for putting Lubriplate on tips of valve stem - assume that is same as white lithium grease.

5. When resinstalling rocker arms say position No 1 piston on TDC at end of compression stroke -how do you do that?

Bunch of newbie questions but would like to tackle this myself. Thanks in advance.

 

use a flashlight in the sparkplug hole, a clothes hanger, or whatever else you have handy to bring the cylinder up to the top. this will ensure the valves cannot fall down into the cylinder while you have the spring off. the valves should be oily anyways, i doubt lube will be needed. they are umbrellas right? if they are you dont need to worry about getting them onto the guides, you jump slip em on and your done

 

Pressure doesn't matter that much. Enough to hold the valves in position. I started out at 10 psi when I did mine but bumped up to 45-50 psi by the time I was done because valves weren't holding enough. The only problem with the higher pressure is that if the engine isn't right at top dead center the piston may move. Closed position for the valve is the valve all the way up. Just leave the pressure on the cylinder till that cyclinder is done. Do one cylinder at a time.

 

Pull all of the rocker arms first... but keep track of them so they can go back to their previous position upon assembly.

Use all of your air pressure.... if the piston movesso what,,, as long as you have good air pressure the valve ain't going anywhere. I did not care if the piston remained at tdc or not,,, just keep your pressure up and no sweat.

It doesn't take long to remove the spring and replace the seal, work one valve at a time exclusively, while keeping air pressure in the cylinder the whole time.

Engine assembly lube will work on every surfacewhen going back together, including the valve tips,,

To find TDC on #1 have a helper bump the starter, with the sparkplug removed and the end of your finger in the sparkplug hole, when you start tofeel compression go past your finger, watch very carefully for the timing pointer and the TDC line on the balancer to align. When they do, #1 is at TDC.

Is it a good idea to have the piston up in the cylinder when changing the valve seals? Probably is,,, but I don't have that kind of patience..... I didn't worry about it...

 

Thanks for the tips - one last dumb question. Exhaust valves are the valves closest to exhaust manifold - intake valves are the inner ones closest to intake - correct?

 

Palerider,

Without looking, but, having done this last winter, I believe, starting from the front and working toward the firewall, driver side, theIntake is first followed by theexhaust valve. It is the opposite for the passenger or number one piston.
Good Luck with the umbrella seals. Though, if you could hold off until you are in a position toremove the heads, the posi-lock seals are much better. But, this requires total dismantling and maching the stem bosses.

 

Yes, the valve will be generally in line with it's respective port.

 

Okay I lied one more dumb question and I'm ready to tackle it. Bought a spring compressor, line to push compressed air into the cylinder. Triedputting compressed air into cyl 1 and 8 and in both cases I could hear air hissing out of the breather cap and compressor kicked on a couple times.Did it both with car cold and warm.I have a small 2hp compressorthat I think it should be okay especially if i only need to pump 40# or so into it. What do you think?

Also, I thought when you hear air coming out this is a sign of bad rings. Did compression test and it was pretty good.Is some air coming out of the breather normal? Did a leakdown on # and when cold it was way out of wack 30% drop but warm it was less than 10%.

Apprecaite all the advice on this one. Done little things mechanicall springs, shocks, waterpump, front end - but first time really on internals.

 

Yea, you are going to have some air blowing by the rings. They aren't a perfect seal. The valves should be a perfect seal when they are closed though so as long as you don't have air coming out of the carb or the exhaust, your fine...

 

You can also try the old-school method of using a length of 1/2" diameter rope threaded into the cylinder through the spark plug hole.
Insert as much rope as you can into the cylinder then rotate the engine to bring the piston up to compress the rope.
This will hold the valve up while you replace the seal. When the seal, spring, and keeper have been replaced just rotate the engine and bring the
piston down then pull out the rope and move to the next cylinder!