Went to replace my valve seals on my 302. Heads on engine and in car. Bought the air adaptor to keep valve up when locks removed. Removed 1 bank of spark plugs. Went to connect air hose to adaptor and engine started to turn over which was fun since it was in gear. I'm running 70 psi. What is the minimun pressure you guys have used to keep the valve in place. May have to go with the rope if this don't work.
Suggestions welcome.

the rope works good.
I suppose if the hole you're doing starts out at bottom dead center it ain't gonna go nowhere tho

Need to remove all plugs when doing this and it would not hurt to loosen all rocker arms or remove in preparation. Sorta depends if you are using the pry bar tool or spring clamp. Be ready for motor to turn over thus pushing piston to bottom when using air.. 70 psi will work.

As Jim said rope will work also but piston needs to be at top unless you want to hand roll it over until piston "feels" solid against head or valves. If you use the rope, this gives an opportunity to try and wiggle valve with spring released, in their guides to see how worn they are...

Bet a bucket of hog liver, that you got worn guides too. I could say "dollar to donut'' but we dont say that in Texas.

Thanks for the quick replies. I heard 3' of 3/8 rope. Does that sound correct? Sounds like an awful lot of rope.

I'd think 3/16" or a 1/4"...

Just make sure it has a big knot in one end so it can't get swallowed..

Personally, I'd use 1/8" stuff b/c it would really thread in easy to me..

pdq67

Compressed air is a much better idea if you have it available.
I wouldn't bother with rope at all if you're trying to crack the valve locks loose.

With air, if your valve is say, 2" in diameter, you have 3.14 square inches of valve-head area. 3.14 x 70psi = 220 pounds of force holding your valve in place while you remove the locks.

With rope, well, if you have a piece of rope unevenly under the valve-head and you pull down hard enough to crack the locks loose, there's a good chance you'll bend the valve.
Rope is fine if you just want to hold a valve in place.

I've used the rope method MANY times. Just get a standard coil of cheap clothesline. As Paul said, make sure it's not possible for it to get "swallowed."
Stuff in all that will fit, then bring the piston up till it's jammed solid. It will hold the valve. Seems low-tech, but it works.

Quick question, started to take valves apart and there are no rubber umbrella's installed. Just the rubber o-rings. I have the umbrella's that look like they will fit. Do you guys recommend using them too.

The umberalla type is called the old ford type seal.. If that seal is small enuff to fit unside the valve springs and over the valve stem boss, then you can use them too. Some are rubber, some are a hard plastic. The hard plastic are prone to get brittle and break . The best are the ones that require cutting the valve guide boss, some times call the PC seals , they have the wire band aroung the bottom for retention. If you suspect valve guides are getting bad, the umberalla type will help you out. You dont have to install 0 ring type if you use umberalla type. I sent you a pm.

the seals you are using are viton positive seals...they are much better quality than the old o-rings...i usually use them on both in and ex valves, but i`ve seen them used only on the in side, with rings on ex...compressed air works great...use a brass hammer and hit the outside of the spring cap on the edge so it cracks the crapring loose(for lack of a better term) and the spring cap will push right down past the keepers...i got a really cool tool from snap-on for doing these...its kinda like the old socket trick, where you put a socket over the keeper and hit it down with a hammer, only inside of the socket tube there are magnets that extract the keepers...works ausumn, and saves a ton of time...reinstalling is real easy too...another part of the tool goes between the keepers...u hit it with a hammer, collapse the spring and it pushes the keepers into the spring cap...cost like 45 bucks...worth every cent...

Back in the 70s we would use Vega valve seals on all of our V8s. There worked great in stopping oil from getting past the guides. I would think they have better seals by now :) . I haven't built any engines since the late 80s....



Kev

I use Crane teflon seals.. I'm quite happy with them.
Viton seals might be a good choice too. Has anyone tried Viton? I'm keen to know what they're liike..

http://static.summitracing.com/global/images/prod/large/cca-505-16_w.jpg
http://static.summitracing.com/global/images/prod/large/edl-9725_w.jpg

Steve, I have used both and they both require guide boss milling to .500 or so. I currently use the PC type , like the black but with teflon inserts. Seem the white "Crane " type wore down on the stem too quickly for me on the street. I guess it was due to the top wire ring clamp.

I think I took the top ring off when I put mine on??

pdq67

I hate to beat a thread to death but I only want to have to do this once. If I install the seal like the one below on the intake and exhaust, I do not need the o-rings - correct? they fit over the boss fine. What keeps them in place? It seems like they would move with the valve.

http://i55.photobucket.com/albums/g136/Caman355/MVC-002F-14.jpg
http://i55.photobucket.com/albums/g136/Caman355/MVC-001F-12.jpg

They would be (should be) a snug fit over the guide boss. That's what holds them in place. :thumbsup:
If you're worried about oil consumption, just do the intakes and see if it helps before you worry about all 16.
Exhaust seals won't be responsible for oil consumption.

Thanks Steve, actually I've been getting oil fouled plugs after a few hundred miles. I'm already running a 437S accel shorty that is the replacement for the R45 Delco so I have been running a hotter plug. I figured it was the seals as it runs good while running and then seems to get oiled fouled the next time or 3 when I drive it. The 2 valves that I have done so far only had the o-rings on and they were not brittle but had hardened up some compared to the new ones.

I hate to beat a thread to death but I only want to have to do this once. If I install the seal like the one below on the intake and exhaust, I do not need the o-rings - correct? they fit over the boss fine. What keeps them in place? It seems like they would move with the valve.

http://i55.photobucket.com/albums/g136/Caman355/MVC-002F-14.jpg
http://i55.photobucket.com/albums/g136/Caman355/MVC-001F-12.jpg

Those seals are the best available that don't require machining.

They are not intended to lock onto the guide. Just slide them on. The first time the valve opens they will ride up the stem to the height they need to be, and they will go up and down with the valve. The "umbrella design" has the oil dripping down the outside of the guide rather than right down the center. They will do a good job for you.

All of the other seals pistured in this thread require machining the guides.

oh, yea, correct, do not use o=rings with those seals, only the umbrella.

Using 2 seals would most likely create a stack that would get "squished" between the guide and the retainer as the engine runs, trashing both seals and forcing you to start over.

Those seals are the best available that don't require machining.

They are not intended to lock onto the guide. Just slide them on. The first time the valve opens they will ride up the stem to the height they need to be, and they will go up and down with the valve. The "umbrella design" has the oil dripping down the outside of the guide rather than right down the center. They will do a good job for you.

All of the other seals pistured in this thread require machining the guides.
Pistured?
New word for world dictionary. Good morning , Jim.

Awesome!. Thanks guys. This makes it alot easier.