thunderstick

Looks like I'm on my own to do this... I thought I was gonna have some experienced help, but apparently not. Anyways, I have a basic knowledge of it, but need some technical advice. It's '91 L98, 109k miles. Isn't there like a sequence of doing them, etc., and then I'm not 100% sure on resetting the valves themselves. I'm thinking it's to tighten them til the rod just stops turning and then go another 1/2 turn? Isn't there 2 different seals - one for int and one for exh? Any help is appreciated... I shoulda' done this last year when I had my covers and intake off, but we won't go there... thanks...

KAM

okfoz

To change valve seals you will have to find a way to keep your valves from falling into your cylinders. You let one go and you will have to remove the intake & then the heads.

(Some Aircraft mechanics used to remove the spark plug and stuff Rope into the cylinder to keep the valves from falling in) Sounds kinda risky to me, and like a pain, since getting to the plug holes is difficult enough to put the spark plugs in, let alone a rope...

Remove the rockers then springs and go to town, it looks like a real pain, unless you do what i do, remove the heads, give it to my machine guy for a valve job...

There might be a better Idea out there, but I thought I would give my 2 1/2 cents (Inflation)...


John

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87 Formula 5.1 converted to TPI Yellow/Black
SLP cam, headers, cat-back exhaust
Ported & polished TPI intake
Gil Younger (no yo-yo) Shift Kit
Aluminum Driveshaft
3.73 Posi gear
Baer 12" brakes 4 wheels
Hotchiss strut tower brace
South side machine frame connecters
Custom reinforced control arms and pan hard bar.
Custom Leather interior

87 Formula TPI (5 Speed) Yellow/Gray STOCK

83 Camaro (Parts)
83 T/A (parts)

http://www.3rdgenformula.com

thunderstick

Yea, I know about the valve drop thing... I have a compressor and fitting to keep the valves "pumped up" so they don't drop...

KAM

Scott 88 GTA

As long you have a tool to compress the valve spring while it's on the head then you're all set. You'll just need to do one cylinder at a time, order won't matter since you're using compressed air (with the rope method you always have to do each cylinder while it's on the compression stroke so that the piston is at the top so a minimum amount of rope is needed, and both valves are closed). I believe you're right on the tightening of the rockers, but it's been a while since I've done mine. Check a manual, it should be an easy procedure to find.

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Black 88 GTA L98
261 RWHP, 345 RWTQ
13.406 @ 103.72 MPH
ZZ4 bottom end, Edelbrock 6085 heads, LT4 HOT cam, GMPP 1.6 RR's, ported stock TPI, SLP 1 3/4" headers, no cat, Dynomax cat-back, Stock PROM
E.T.F.A Member #11

Kevin Irving

Phil Parsons has an outstanding article on his site which I followed when I did mine about 2 months ago. http://www.racer-x.f2s.com/proc/vseals.htm. As far as setting valve lash, wouldn't you know he also has an article about that too!! http://www.racer-x.f2s.com/proc/vlash.htm. I put 3/4 turn on mine after zero lash and haven't had any problems. Some people say putting in more turn actually helps in higher RPMs. The entire job took me about 2 days with a friend helping me out the first day with the driver's side and me doing the passenger side on my own the second day. The hardest ones to do is the #s 7 & 8 because the firewall is THISCLOSE to your work area. Good luck.

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Kevin Irving
85 Trans Am WS-6, 305 TPI, custom burned '86 PROM with '87 "165"ECM, Accel Supercoil & 8.8 Wires, Rapidfire #2 @ .055", MSD 6AL, 1.6:1 Roller tipped rockers, Homemade AFPR, K&N cone, no airbox, Aluminum Driveshaft, Wonderbar, TB Coolant Bypass, Ported Plenum, Descreened MAF, Syclone Fuel Pump, JET Airfoil, Mobil 1 synth in all but transmission.

15.556 @ 86.65mph, Nov 10, 2000.... I know it sucks.. but it will get better!

http://www.geocities.com/transam85tpi/

Member - The Tidewater Trans Am Club, Norfolk VA http://www.geocities.com/ttacva/

Suaveat69

Only go a quarter turn. Helps it rev faster. I know but anything helps these motors.

thunderstick

Thanks, Kevin... the links you provided didn't work, though. I'll try from home, cuz sometimes the server at the jobsite acts retarded and might be the problem. Didn't you use to be in Norfolk?

KAM

camaro6spd

don't work form here......I would also like to know this.. I will be rebuilding a 350 so the head will be off. What kind of work is involved then? How much do machine shops want and what tool are needed?!

Kevin Irving

Thunder.... Yep, I used to be in Norfolk, but, duty calls, I've transferred to Bremerton, WA to go on the USS Carl Vinson which is where I report on Sunday.

Just about any mech will charge around $200 to change the seals with the heads still on the car, that's about the average rate. If you take the heads off and take them into a machine shop I've seen them work the heads, (no port or polish, or decking, just valve job) for about $125 for the set.

I don't know why the links don't work, so I'll just cut & paste for you here....


Replacing Valve Seals
By Phil Parsons


Tools:

A good mechanic's tool set (sockets, wrenches, etc.) - important: make sure you have needle nose pliers.
Overhead valve spring compressor (the one for compressing valve springs on the car looks like a modified two jaw puller).
Air compressor (one with at least 100 psi line pressure)
Spark plug adapter for compressor hose.
Valve lock removal/installation tool (optional, I give easier methods)
Safety goggles.
Parts List:

Valve seal set (note: seals usually come 8 to a package, and exhaust will usually be a different part#).
Valve cover gasket set.
Clean, preferably lint free towels.
Procedure:

1. Remove the valve covers. Cover all oil drain back holes with the towels to prevent small parts or other junk from falling into the crank case.

2. Work on one head at a time, and do the cylinders in order (front to back or vice versa) so that you don't lose track of the ones you have done already. Loosen the rocker arm enough to rotate it out of the way of the valve/spring assembly. Remove the spark plug, and thread the air hose adapter into the spark plug hole. Attach the air hose and let the compressor pressurize the cylinder. This will keep the valve from falling into the cylinder when you remove the spring. The engine may rotate slightly as the pressure pushes the piston down to BDC. (NOTE: See the bottom section (ALTERNATE METHODS) for alternate ways of accomplishing this).

3. FOR THIS PART MAKE SURE YOU ARE WEARING GOGGLES!! Use the valve spring compressor to compress the valve spring. Occasionally the compressor will lose it's grip, and the spring could bounce out. If it does, that sucker will be doing about Mach 5, and there is NO time to duck, so wear the damn goggles! As the spring compresses, you will notice a pair of small half moon shaped pieces holding to the top of the valve stem. These are the valve locks - use the needle nose pliers to CAREFULLY remove these pieces, and lay them aside in a safe place. If you drop one (and you almost certainly will) you will be glad that you followed my advice about covering the drainback holes with towels. Once the locks are removed, you can remove the spring completely from the valve. Leave the compressed spring in the tool - it's a bitch to reattach the tool with the spring and retainer loose.

4. With the valve spring completely exposed you will see what's left of the seal on the second groove down. Remove the old seal, and make sure that the valve stem is clear. Again, make sure that the towels are in place over the drain back holes in the head to catch the pieces of old seal. Inspect the tip and groove areas of the valve stem for any signs of burrs, mushrooming, or sharp edges. If you find any, they must be removed with a grinding stone or file, or the valve itself must be replaced. SHARP EDGES OR BURRS WILL DESTROY SEALS DURING INSTALLATION. Because the seals for intake and exhaust are usually different, I will give different procedures for each.

5. FOR INTAKE AND EXHAUST "O-RING" SEALS - The seal must be installed AFTER the spring is put back on the valve. If you install the spring and retainer over the seal, you will probably damage it. Lubricate the valve stem with a light coating of oil. With the spring and retainer still in the tool, install them back on to the valve stem. LEAVE IT COMPRESSED. Lightly coat the valve seal with oil, and slip it carefully over the stem, seating it in the bottom groove. NOTE: not all small block V8 engines came with o-ring seals on the exhaust valves. Those that did not will only have a single groove machined into the valve stem.

6. FOR "UMBRELLA" TYPE SEALS - The seals are installed BEFORE the spring goes back on; the set will usually include an installer tool (looks like a plastic tube) and instructions. Lubricate the valve stem with a light coating of oil. Install the seal per the instructions, then install the spring (still in the compressor tool) and leave it compressed. Usually these seals are simply pushed down until the bottom contacts the valve guide boss - the seal will be positioned automatically when the engine is started for the first time. IMPORTANT: Make sure that the flat inner damper spring does not contact the seal after installation - I would recommend turning the engine by hand to allow the valve to go through its full range of movement to check this. In some cases this spring rubs against the seal and will turn it into cole slaw when the engine is started!

7. FOR "POSITIVE" TYPE GUIDE MOUNTED SEALS - NOTE: This type of seal requires that the valve guide boss in the head be perfectly concentric in relation to both the guide and the valve stem. This requires that the heads must be removed and the valve guide bosses be machined concentric by a competent shop. If the heads have not been machined for this type of seal, the seals will fail to work properly. These seals are installed before the spring is reinstalled. Lubricate the valve stem and inner seal surface with engine oil before installation. Normally the seal manufacturer will provide a thin flexible plastic sleeve that will protect the seal from getting shredded on the valve stem grooves. Some sets may require a special installation tool, but normally a deep socket that is sized so that it will contact the seal squarely will work just fine. FINAL NOTE: It is very important to check the retainer to seal clearance. With the valve at maximum lift there should be at least 0.070" clearance between the bottom of the valve retainer and the top of the valve guide (To measure this clearance, the valve must be opened to the specified maximum lift with the spring not installed, using a dial indicator or machinist's ruler to measure the valve opening. Therefore it is not recommended that this type of seal be installed with the heads mounted on the engine). If there is not enough clearance, the seal will be destroyed when the engine is started, and there is also the possibility of valvetrain damage from the retainer bottoming out against the seal.

8. Reinstall the valve locks on the top groove, and loosen the spring compressor until the spring is fully seated. Sounds easy, right? It's not. The locks are tiny, and they have a nasty habit of not staying in the grooves before you can get the spring uncompressed. (Again you will be glad that you were smart and covered over the drainback holes). You can buy an expensive valve lock tool from companies like Matco. What I usually do is to install the valve locks and then hold them in place with one hand, then pull the spring/tool UP so that the locks are held in place by the spring. Then while holding the tool up, loosen it so that the bottom of the spring moves down into the seat. Make sure to keep the tool centered so that the spring seats correctly on the spring pad.

9. Now, put the rocker arm back in position, and tighten it only enough to keep it in place, and go on to the next one. Later, after all of the seals are replaced, set the valve lash on all cylinders together - lashing them one at a time is time consuming and error prone.

10.Click here for the procedure on setting valve lash.

11. Reinstall the valve covers.

ALTERNATE METHODS

I know that some of you out there can't afford compressors. Don't worry, there are other ways to keep the valves from falling in.

The first method was passed along by Tom Keliher (Tom and his superlative Firebird can both be found at THIRDGEN.ORG). Tom used to work on airplanes, and his method is incredibly simple: Make sure that the cylinder that you are working on has the piston at TDC (Top Dead Center). The valves might fall a little, but no way are they going all the way in. To find TDC on any particular cylinder, remove the spark plug, and stuff a wad of tissue paper into the hole. Rotate the engine by hand, and when the tissue pops out, you are close enough to TDC to be safe.

The second method comes from Mike Bone. Like Tom, Mike and the "Bone 'Maro" (get it?) can be found at THIRDGEN.ORG. Mike's method is to feed nylon rope into the cylinder through the spark plug hole until the cylinder is filled, effectively preventing the valve from falling in. This is a bit easier than Tom's method, but less accurate. It is extremely important to make sure that the cylinder is completely filled with rope!

Setting Valve Lash
By Phil Parsons

Procedure:

The procedures here will be much easier if you rotate the engine to top dead center (TDC) on the #1 cylinder beforehand. There are many ways to do this, but I have found that the easiest way is to remove the #1 spark plug, and stuff a tissue into the hole (no, not ALL the way in). Rotate the engine by hand until the tissue pops out, indicating the compression stroke. Then make sure that the timing mark on the balancer is exactly lined up with "0" on the timing indicator - you will then be exactly on #1 TDC.

1. Most manuals recommend starting at #1 TDC, and then setting the lash for intake valves on cylinder #'s 1, 2, 5, and 7, and the exhaust valves on #'s 1, 3, 4, and 8. Then you rotate the engine 180 degrees, and do the rest. I think that this method can be confusing, especially for novices. I have found is that an easier way is to follow the firing order, and to do both the intake and exhaust valve lash on each cylinder. In other words, set int and exh on #1, then rotate the engine until #8 is at TDC, and set both of those. Then go on to #4, then #3 - you get the idea. It takes a little longer, but there is FAR less chance of mistakes.

2. Spin the push rod with your fingers, while slowly tightening the rocker arm nut. When the slightest drag is felt on the push rod (in other words when the rocker first rests on the push rod tip), STOP, and then tighten the rocker nut 1/2 to 1 more turn to apply the lifter preload. A common mistake is to tighten the rocker nut until the push rod can't be spun any more - this is incorrect, and can leave the valves stuck wide open, inviting disaster. An easy way to avoid this is to not do it.

NOTE: If you have a dial indicator, the factory recommendation is 0.030" for the preload setting. Use this instead of counting turns of the rocker nut - it is far more accurate.

NOTE: There is quite a bit of controversy over exactly how much lifter preload should be applied. Most repair manuals specify 1/2 turn. For performance applications, some (TPIS in particulr) found that 2 turns or sometimes 3 turns are more beneficial. 3 may be a bit too radical for the street, though. Frankly every engine and application is different, so I would recommend experimenting to find the best value. Start with the factory setting, and then go in increments of about 1/4 turn, testing performance and driveability after each increase in preload.

3. IMPORTANT: If you are doing other work to the engine, make sure that you remember to turn the engine back to #1 top dead center.

©1999 Phil Parsons (The Best Damn Garage On The Net)

thunderstick

Thanks, Kevin... got it printed out.

Looks like I'm headed to Norfolk in a few months...

KAM

mjdoyle

The links will work if you erase the period (.) after htm

http://www.racer-x.f2s.com/proc/vseals.htm

try this

ZPI28

I put new valve seals in my 91 Z28 about 6 months ago. It took me about 6 hours to complete. Number 6 and 8 were the most difficult because of the a/c. No need to remove the intake. I used my air compressor to hold up the valves. My oil drain backs were stopped up causing it to smoke when left at idle. I adjust my valves with the engine running I listen to the valve when it stops tapping I go another 1/4 to 1/2 turn on it. After replacing the valve seals and cleaning the drain backs I ran some 5 min motor flush though it and changed the oil no more smoke.Runs great.

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91 Z28 305 TPI
single 3"flowmaster
gutted airbox
170 Tpis thermo
273 gears,auto
9.54 1/8th mile
on goodyear eagles

thunderstick

Thanks for the responses, guys...

What type spring compressor is needed for this?

Also, anybody know what type replacement seals I'm going to need? Kevin?

KAM

Kevin Irving

When you're ready, just go to the dealer and order the new valve seal kit for your engine. The whole set is in there, intake and exhaust, and if I remember correctly there is an extra set of exhaust seals in there that you won't use, so in other words you have 3 DIFFERENT seals in the little bag. IIRC the tan ones are the intake seals, and the black ones with the blue metal band and the metal ring around them are for your exhaust.

The compression tool looks just like a small pry bar, except one end has a rubber handle on it, and the other end you can tell sits on top of the valve spring and there is room to remove the retainers and put them back in. There is a slot at the bottom of the "J" of the bar where the stud goes through. It's pretty straightforward. If you have any questions at all about the tool ANY reputable shop, (and even the not so reputable ones) has the tool, and some parts stores might even have one to loan out. I borrowed the one I used from my mech at the dealer.

Another good idea is to pick up about 4-5 extra keepers (the little half circle things that sit in the top groove of the valve stem) because you will probably lose a few. I got REALLY lucky and didn't lose any, (knocks on head) If you have any other Q's, don't hesitate to post here or just e-mail me.... you'll be fine.

I ROCK

Anyone - would a Top Dead Center locator work to hold up the valve stem? That is, would making sure the cyllinder of the seal you're working on is at tdc keep the stem up? Thanks.