The Stovebolt Site Forums The Shop Area Engine Shop how do I install valve guide seals?

Ok, I guess my 261 sat for too long without running because my valve guide seals are toast and she smokes on long downgrades and uses a quart every 300 miles. The rings seem ok but I know the valve guide seals are shot. How do I replace them? I have an extra 848 head with good valves that I want to fix on the bench and install onto the engine when I am done. I am assuming I need a spring compressor to remove the valve keepers. Then what? What are the best seals to use?

The job can be done without removing the head. You will need to have a way of putting air pressure to the cylinder at TDC to keep the valves closed.
Remove the rocker assembly as it will be in the way.
Get the keepers and locks loosened by taping on them with a hammer (brass preferred). There is a cool tool that you can compress the valve-spring while the head is still on the engine( I may be able to bring it up that way in a week or so).
Compress the valve-spring and remove the keepers. then let the pressure off the valve-spring and remove it from the head. Remove what is left of the old seal and install the new seal(there is a little plastic cap that slips onto the valve-stem to protect the seal from getting cut). Install the valve-spring and keepers and go on to the next one.
It is a lot easier to do the job with the head off and it will also give you an opportunity to inspect the valves and top end of the cylinders & pistons.
You may want to replace the valve-guides at that time too as well as have hardened seats installed.

Local auto parts stores (Kragen, etc.) often rent out valve spring compressors, I think it's $7/day. There are two kinds - one that requires the head to be off, and the kind that works with the head on. Just be sure you get the right kind.

-Boyo

Thanks, I guess I can probably borrow the tools from Autozone. How do I tell if I need new valve guides? (assuming I'm working on my spare head)

The guides will need to be measured with a hole guage and a micrometer
The hole guage I am referring to has a thumb-screw at the end you grab onto and it expands the end that fits in the guide, then you measure that with a mic.
I have gotten away with some pretty sloppy guides on some of my old junk. It would not be optimal for racing but with a new seal and no leaks or oil smoke, I guess I was lucky.
One engine I had in my 72 had a burned exhaust valve. I took one out of another head, stuffed it in the hole, (not too much play between the stem and guide) and twisted it to see if it made contact from the seat to valve face. Made a shiney thin ring on the valve face, installed a new seal and drove it for 2 more years

To check for guide wear, just grab the stem when you have the spring off. You shouldn't feel much side to side. Something like .0001 - .0003". If you have much at all they most likely need replace. New seals will help for awhile. Rebuild the other head when you get money or time and swap it back on.
Joe

Four,do it with compressed air as said above,K&D makes a small compressor with a hand wheel on the top, works well ,cost less than 20 bucks.use the cheap umbrella seals used on Chevy small blocks.You can do the intakes only if you are lazy.If the engine sat around, the rings and or cylinder bores are probably not in the best shape.Compression or leak down tests tell nothing about oil control,so if the seals solve the problem, good.I feel it always pays off in the long run to rebuild an engine in the first place if you're gonna use it regularily.

I like to do one extra step when doing seals with head on block. I do one cylinder at a time and bring that piston up to the top. I don't want to take a chance on losing the air seal and the valve dropping in. I do this even though in reality there is usually enough crud baked on the stem and the top keeper groove is probably hammered enough that it would never fall through on its own. If I do have to use a hammer I do it with the piston down and I set a socket on the spring retainer and tap it.

Hi, I'm new here. I'm trying to replace the seals on a 350. When I apply air (probably 100 psi) it turns the engine. How much air pressure is correct?

If you are going to use air you have to have the piston at bottom dead center on the cylinder you are working on, or the engine will turn until it gets there.