Gen 1 SBC 350 Valve Stem Seal Help - Hot Rod Forum : Hotrodders Bulletin Board
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Old 10-11-2013, 03:45 PM
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Gen 1 SBC 350 Valve Stem Seal Help

I have a Chevrolet Performance 350/290HP Crate Engine 809-12499529.
It came with the Chevrolet Performance 809-93438648 Cast Iron Cylinder Heads.
Features
Cast iron
No heat risers
Uses 1.94"/1.50" valves
Straight spark plug design
Combustion Chambers: 76cc
Standard 6-bolt intake manifold pattern
Requires 14mm thread, .460'' reach, 5/8'' hex, tapered seat, projected tip spark plugs

I need to replace the valve stem seals. The factory seal part numbers are:

Intake: Chevrolet Performance 10212810
Valve Stem Diameter:0.344 in.
Valve Stem Seal Type:Umbrella
Valve Stem Seal Material:Rubber
Machine Work Required:No
Valve Guide Diameter (in):0.500 in.

Exhaust: Chevrolet Performance 12564852

Can I replace the Intake and exhaust seals with:
Trick Flow Valve Seals TFS-30400454
Valve Stem Diameter:0.344 in.
Valve Stem Seal Typeositive stop
Valve Stem Seal Material:Viton® fluoroelastomer
Machine Work Required:No
Valve Guide Diameter (in):0.500 in.
Valve Stem Seal Outside Diameter (in):0.630 in.

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Old 10-11-2013, 04:27 PM
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These are common replacement parts. If you go to parts store. Order Fel-Pro seals for an early nineties 305 or 350. You will get the correct stuff.. Blue color positive intake seal and a white plastic exh seal. Usually the old style O-rings are included. You can also use them with the other seals or not. GM quit using them when stock ran out and changed over to single groove valves..
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Old 10-14-2013, 08:39 AM
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Well so much for that. Turns out the heads were not machined at all and they only had O-Rings on the valve stems. So much for GM installing what was listed in the specs for the motor.
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Old 10-14-2013, 09:29 AM
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Here is the casting number.

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Old 10-14-2013, 04:12 PM
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Hecho en Mexico... Should already be cut for seals.

Can't really tell by the camera angle.
but looks like it has a seal on it..

Yes they used two grooves on production engines till the inventories ran out..Then went to single groove valves with the same seals..
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Old 10-15-2013, 12:44 AM
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Heads weren't cut for seals and I installed the O-rings all the way down the shaft instead of in the 2nd groove. I going to compress the springs and install new O-rings in the second groove through the top of the retainer tomorrow.
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Old 10-15-2013, 04:35 PM
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Well I left the 1st set of O-rings down on the shaft and installed a another set on the 2nd groove at the top of the stem. Now it's back to factory (at least how GM put the heads together). Hopefully that takes care of the oil fouled plugs and white puff of smoke on start up issue. If there continues to be an issue I will be forced to pull the heads and have them machined to except positive lock seals.
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Old 10-15-2013, 07:04 PM
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You should have installed some Viton positive seals on there or at least some umbrella's. The orings don't do much or for very long
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Old 10-15-2013, 07:39 PM
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Quote:
Originally Posted by GMC boogie View Post
You should have installed some Viton positive seals on there or at least some umbrella's. The orings don't do much or for very long
Unfortunately the heads were not machined to accept any type of seal other than just O-rings. The motor has a little over 60,000 miles on it so I guess I will just have to replace the O-rings in another 50,000 just to be safe.
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Old 10-15-2013, 08:06 PM
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Did you measure the OD of the boss? There are different sizes of positive seals that may have worked for you. A good Viton umbrella seal rides on the stem and fit whether the bosses have been machined or not.

Not trying to bust your chops, just hate to see a fellow gearhead go the route you went when you had better options.
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Old 10-15-2013, 08:23 PM
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Quote:
Originally Posted by GMC boogie View Post
Did you measure the OD of the boss? There are different sizes of positive seals that may have worked for you. A good Viton umbrella seal rides on the stem and fit whether the bosses have been machined or not.

Not trying to bust your chops, just hate to see a fellow gearhead go the route you went when you had better options.
The boss is a little smaller than the inner diameter of the spring since they are not machined. I will look for some umbrella seals that are larger and will fit under the spring for the next time when I feel like pulling everything apart.
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Old 10-16-2013, 06:20 AM
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Valve stem O-rings will not work without oil shields over the valve springs. The oil shields will not fit valve springs larger than 1.300" O.D.

I noticed in the photo thay you have ommitted the oil shields. If your valve springs are larger than 1.300" O.D., you must omit the shields and o-rings and install Viton postive stop seals on the valve guides with phosphor bronze valve guide liners and tighter valve stem clearnces... .001" I / .002" E. stem clearances.

After you do that, you can omit the shields and o-rings. Until that is done, become accustomed to seeing oil smoke when the engine starts and consuming oil past the valve stems along with a loss of power due to oil contamination of the combustion mixture.
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Old 10-16-2013, 06:57 AM
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What I'm wondering is why the heads came this way from the factory. The only thing I have done to them in the past is replace the springs and when that was done there were no shields present. How it's setup now is exactly how it came from the factory.
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Old 10-16-2013, 07:30 AM
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Those heads came from the factory with oil shields. Whoever did the last valve job left them off.

The BB Chevy and Pontiac Ram Air IV heads did not come from the factory with valve spring shields. That is because those valve springs were 1.512" O.D. The BB Chevy and RA-IV heads were machined for positive stop valve spring seals.

If your valve springs are less than 1.300" O.D. you can install the oil shields (GM-10007818) and o-rings and that will be cheaper than removing the heads and installing positive stop seals.

Last edited by MouseFink; 10-16-2013 at 07:56 AM.
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Old 10-16-2013, 08:55 AM
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The outer diameter for my Edelbrock springs are 1.222 in. Will the GM-10007818 shields work?
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