oxygen454

Starting on a valve seal job tomorrow on a 1988 5.0L Firebird. I have some questions...
1. How many psi of air pressure do I need to keep the valves up in the engine?
2. What is the torque for the valve cover bolts?

Ransford2987

http://www.enginebasics.com/Advanced...n%20Motor.html

Valve cover bolts are somewhere between 2 and 7 ft-lbs. I wouldn't go any higher than that unless you aren't getting a good seal.

oxygen454

Great thanks! I remember reading that site months ago. Now the next question would be how big of a tank or cfm I would need? My small compressor probably won't supply enough constant air pressure?

Ransford2987

That depends on the leak by past your cylinder rings. I'd say try it and see if your pressure stays relatively constant. I don't know the common cfm leak by for this. Maybe you can find something, but I would guess it has a lot to do with the specific engine, age, previous maintenance, etc.

sofakingdom

iTrader: (1)

I have never found air pressure to be a particularly good way to do this. In fact, it usually seems to spectacularly fail.

I prefer the rope method.

Damon

I use my 5 HP 20 gal compressor and it keeps up just fine. Kicking on and off from time to time. Not sure how well it would work with a little totable compressor- the kind you see with the m&m shaped tank on the bottom.

I usually run about 100 PSI to it, but you can do it with less. The main thing is to give the retainers (not the valve stem) a good crack or two with a mallet before you try to compress the spring to get the locks out. The locks tend to like "sticking" to the retainers from all the time, pressure and wedging action that's been holding them together.

eseibel67

I have done it both ways, and I agree. There's just too much mental stress in hoping everything will hold up while the pressure is on. With the rope method, valve seal replacement is quite liesurely. You can even stop for lunch without worry.

rusty vango

I learned this trick in 72. yes there are other ways, but the rope idea is best by far.

oxygen454

Great rope trick it is! I like that idea too. I also don't have a large enough air compressor right now. Thanks!

oxygen454

How many feet of rope would I need? 10 feet? I have lots of nylon rope I could use.
Also can I do the intake and exhaust valves at the same time?

midias

I have a 5 foot section of rope that is about the same diameter as the plug hole works great.

oxygen454

So the valve cover is off, wires and alternator. How do you guys see where to put the rope lol. All by feel...

sofakingdom

iTrader: (1)

Ya just put the cyl you're working on @ TDC, stuff as much in the spark plug hole as will fit, and go to town. Do both valves on that cyl, do the other cyl that's also @ TDC at the same time, (4 cyls away in the firing order: 1 & 6, 8 & 5, etc.), rotate the motor 90°, do the next 2 that are @ TDC, repeat.

Keoman

iTrader: (3)

haha rope method.
thats very.... practical.

oxygen454

Trying to get the metal lines off the headers. I think I need a brake line wrench as my wrenches don't seem to fit.. Metric or standard won't fit

Damon

What? What metal lines? Are you talking about the air injection tubes? If so, they don't need to come off for this procedure, unless you're just trying to get a little more working room up around the valve deck area. If that's the case, you're WAY better off removing the header from the cylinder head and laying it aside than you are trying to take those lines out. They'll break half the time before you get them to come free.

And I'll tell you, I've done about a hundred of these little in-car spring/seal jobs over the years. I used to use rope because I didn't even own a compressor. When I got a compressor, I never went back to rope again. I don't get what people have had problems with using compressed air. It's dirt-simple. You don't have to bring the piston to TDC, the valve ISN'T going to fall into the cylinder unless you do something colossally stupid and the job takes about 1/3 the time. With 100 PSI of pressure fed into the cylinder there's about 250 lbs. of pressure holding the valve closed. If you need more than that to slide a new seal down the valve stem, you have bigger issues.

oxygen454

Thanks for the info I really appreciate it! Yes those 1/2'' lines make it hard to get to the passenger rear plug. The rope trick worked so far. If I can get ahold of an adapter for the plug threading from a compression tester or the hose that you can buy that is made for valve seal jobs, I will try it. Finding tdc on the engine is a bit of a pain and getting the rope in the plug hole far back in the engine really sucks.

Her seals were totally gone. The intake and exhaust seals totally missing. I'm half way done. Took most of the time pulling coolant lines, wires, and alternator. Easy but time consuming.

This is my 2 gallon air compressor haha. Its okay for filling tires and a using a brad nailer but does not hold a constant volume of air well. The father-in-laws is a lot larger, probably best to use? The reason I ask is because I also have do this to my VW so more knowledge, the faster the job will be. Also why I'm trying the rope and maybe air.

Damon

If you own a compression tester gague, you probably already own the hose you need to do this with compressed air. Just unscrew the little one-way valve stem core from the end of it and you can shoot compressed air into the cylinder with it. They often have a quick-connect fitting on the other end where they attach to the gague head that's identical to your common air tools. Hooks right up.

Just DON'T lose that little stem seal when you take it out of the hose. It LOOKS identical to the kind used in a tire valve stem, and it will interchange with one perfectly, but it's not the same. Your compression gague will never read accurately again if you replace it with a core from a tire valve stem (the spring inside it is much lighter than in a tire valve stem core).

Typical example:

http://www.sears.com/actron-cp7827-c...p-00902171000P

AND YOU GET A FREE COMPRESSION GAGUE WITH THE HOSE! WIN-WIN!

oxygen454

That valve is similar to a schrader valve. I was also looking one you can buy with the air fitting on one end and the spark plug male nipple on the other. The compression gauge sounds like a better idea. More tools to add to my toolbox, and I wont have to borrow one anymore.

oxygen454

Thinking ahead as Im doing this job... Im dreading the rockers. I have never fully understood how to do this properly and it doesn't help that there is a million different ways of doing it. (rockers are not hydraulic)

Here is what I get and dont get...

Turn engine cylinder top dead center rocker on intake should drop to bottom and as soon as it comes up stop (a bit fuzzy here with which rocker is exhaust and which is intake .. aslo if its top or bottom dead center that the work has to be preformed at)

Tighten rocker nut till zero lash, (moving rocker up and down) then tighten down 1/2 to 3/4 turn (this I get).

Then do each in order (firing order) or do multiple intake and exhaust at the same time (I forget which ones I can do at the same time.. have to check the forums)

I might try following this video given that the rockers can be done in the same order?

Damon

That method will work fine for what you're doing.

With used lifters (that are already filled with oil) "feeling" the zero-lash point were the rocker adjustment takes up all the slack in the pushrod is easy. Half a turn down, give or take, from that point and you're good to go.

oxygen454

To rephrase what I said about the rockers. The rockers are stock so they may be hydraulic? Same ones in the video above...

A guy I talked to was saying I could bring the cylinder to tdc and torque the rocker to spec? I'm not to sure about this way?

sofakingdom

iTrader: (1)

Rockers aren't hydraulic, but the lifters are.

There's no "torque spec" for your lifters. Some engines, there is; not these. Your description is basically accurate if not quite complete.

Best way to do it is, the "EOIC" method (Exhaust Opening, Intake Closing). Install all the rockers, and tighten the nuts until they're on to where the nuts expose about half as much of the stud as they did before you took them off. (maybe 3 -4 threads of the studs protruding) Rotate the engine by hand slowly, watching all the rockers. Watch one kind, let's say, the exhausts. When you see one exhaust just begin to open (Exhaust Opening), i.e. the push rod just begin to move, adjust the intake on that cyl to take out all the up/down play in the push rod, then tighten it another ½ to ¾ turn. Rotate the engine exactly 90°, and do the next intake in the firing order. (18436572... so for example if you had just adjusted #3, you'd rotate the motor 90° and do #6, then 90° and do #5, and so forth, 8 times) Then once you've done all the intakes that way, rotate the motor while watching the next to last intake you just did (i.e. if the last one happened to be #7, watch #5) and after it goes through peak opening and then as it just reaches closing (Intake Closing), adjust that exhaust the same way you did the intakes; then do the others in 90° increments.

You can only do one at a time, and it has nothing to do with TDC or BDC. Don't try the "Chilton's" method, where they tell you to put the engine somewhere and adjust 8, then turn it one turn and do the other 8; that method is HORRIBLY imprecise.

Eeeeezy enough to tell which is which; just look at which one lines up with the intake and exh manifold ports. They are EIIEEIIE.

oxygen454

Update: all went well for the most part. I finally got time to finish the car and tested it. Rockers are quiet and the new plugs make the car run great!

Then the coolant tee (not sure what its actually called) decided to break spewing coolant everywhere. Not sure if the hose clamp was too tight? Or maybe was just brittle?

eseibel67

It's called a heater bypass valve, and luckily it's available in aftermarket. Four Seasons part # 74805 should be available at any parts store.

Damon

It's plastic. And old. That's why. But a new one, put a little lube on the inside of the hoses before you slide them on. Spit works fine.

oxygen454

BIG THANKS! The car has never run so smooth and way more power! You guys have been a big help.

New valve seals, new plugs, cleaned the cap & rotor (some buildup) and cleaned intake. No more smoke on start up.


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