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Remove Valve Springs
You can remove and replace the valve springs with the cylinder head installed on engine, or after it is removed.
Cylinder Head Off
With the head off you can use a regular cylinder head spring compressor. Compress the valve spring, then remove the keepers. Remove the compressor. Push the valve off the seat about 5mm then see if you can wiggle the valve stem side-to-side.
Compressor Usage
Cylinder Head On
The valve springs can be replaced without pressurizing the cylinder. You can change the valve springs without taking the head off, without using air pressure. I have used the following methods:
1. Clean rubber hose fitted into the cylinder
2. Clean thin rope pushed into cylinder
Then rotate the piston up, and it holds the valve from dropping
Method 1: Rope Trick
Remove all spark plugs and turn the cylinder until distributor rotor is pointing somewhat before the plug. Then feed in clean 1/4" (5mm) rope until the cylinder is filled. You can also use clean new vinyl hose. Then rotate the engine the rest of the way. The rope will hold the valve from dropping when you undo the spring.
Method 2: Compressed Air
By pumping the cylinder full of air with piston at TDC.
I got an old spark plug, and busted the ceramic part out, and then braised in a fitting that is the same as the tire valve stem.
If you use air you need to have the piston at top dead center otherwise it will try and turn the engine. 10 psi is all that is needed to hold the valves up. A Leakdown Tester is an ideal tool for adjusting the air pressure.
If it's still on the engine, you can do what I always do:
- remove spark plugs
- feed clean small-diameter soft tubing
- turn crank until piston stops
- change the seals
- repeat next cylinder
The tubing inside the cylinder holds the valves from falling down.
With head on engine, take out spark plug, rotate to TDC for that cylinder, insert clean rubber tubing, as much as will fit. This will hold the valve in place. Remove rockers from shaft (on some engines, you can leave them on).
Use a fork type or bar type or an On-Engine Valve spring compressor.
On-Engine Valve Spring Compressor
Or use a forked bar to push the spring down.
Or a bar with a hole in it. The bar I have is basically flat stock turned up on the sides for strength. It's a simple device. I bought it at NAPA 25 years ago, and they still sell it.
Keeper Removal
Remove the two keeper halves (collet), then uncompress the spring. Lift the valve & retainer off. Note the position of the spring so you can reinstall it correct-side up.
NOTE: Be careful not to move the spring seat "washer".
Do one valve at a time, to avoid mixing the parts.