Question on Replacing Valve Stem Seals on 350 Small Block

[Roger D.]

Restoration of the chassis for my '72 Coupe being finished, I'm now working on the engine (350 small block).

I've gotten to the task of re- installing the valve stem seals and springs on the heads. What is the correct method and tools used to re-install the valve stem seals and springs? I know the springs must be compressed far enough down to be able o install the new square-type o-ring seals into the groove but the standard valve spring compressor does not appear to be capable of doing that. Any sage advice out there?

Regards,
Roger

[Joe L.]

Re: Question on Replacing Valve Stem Seals on 350 Small Block

Restoration of the chassis for my '72 Coupe being finished, I'm now working on the engine (350 small block).

I've gotten to the task of re- installing the valve stem seals and springs on the heads. What is the correct method and tools used to re-install the valve stem seals and springs? I know the springs must be compressed far enough down to be able o install the new square-type o-ring seals into the groove but the standard valve spring compressor does not appear to be capable of doing that. Any sage advice out there?

Regards,
Roger

Roger------


Are the heads installed on the engine or off the engine?

[Duke W.]

Re: Question on Replacing Valve Stem Seals on 350 Small Block

The seal kit should have a plastic sleeve. Dab some oil on the seal, install the sleeve and slide the seal down to its groove. The sleeve protects the seal from being damaged by the retainer grooves.

Then with the seal installed, place the spring, splash shield, and retainer on the valve stem and compress the retainer enough to install the locks.

It's a little awkward the first time you try, but by the time you have half of them done you should find it relatively easy.

Assuming the head is on the bench, clamp it down and carve some chamber spacers out of packing styrofoam that will keep the valves in place as you compress the spring.

Duke

[Joe L.]

Re: Question on Replacing Valve Stem Seals on 350 Small Block

The seal kit should have a plastic sleeve. Dab some oil on the seal, install the sleeve and slide the seal down to its groove. The sleeve protects the seal from being damaged by the retainer grooves.

Then with the seal installed, place the spring, splash shield, and retainer on the valve stem and compress the retainer enough to install the locks.

It's a little awkward the first time you try, but by the time you have half of them done you should find it relatively easy.

Assuming the head is on the bench, clamp it down and carve some chamber spacers out of packing styrofoam that will keep the valves in place as you compress the spring.

Duke

Duke------


I've not seen the plastic sleeve supplied in the o-ring-type seal kits. It's usually supplied with Teflon-type positive seal kits, though.

The o-ring seals MUST be installed AFTER the shield and cap (retainer) are installed. So, the order is (1) install the spring, shield, and cap, (2) compress the valve spring, (3) install the o-ring seal, (4) install the keys (locks), and (5) decompress the valve springs.

The seals MUST be installed as described above or the caps (retainers) will dislodge them. One must also be very careful to insure that the seals are not "twisted"; they must be "square" all the way around when installed.

[Roger D.]

Re: Question on Replacing Valve Stem Seals on 350 Small Block

Thanks. The Felpro engine gasket set did not come with the sleeves mentioned.

Joe, The heads are still onthe engine. Since it has relatively low miles on the engine, we are replacing engine seals that can be replaced ...including the valve stem seals. It seems to be your step #2 that is the problem, i.e, trying to compress far enough to get the stem seal in it's groove.

Roger

[Terry M.]

Re: Question on Replacing Valve Stem Seals on 350 Small Block

I have just discovered this is 2014 and a wonderful thing called the Internet exists.
I Googled "Chevrolet Small Block valve stem seals" There were just an amazing amount of results in no time at all. Try it and you can chose your own. Here is a start:

https://www.youtube.com/watch?v=OsGqmOQus6Y

Edit add:

When removing the push rods and rocker arms keep them in the same positions they came from so that you can reinstall them in the same location. Those parts have been intimate for a long time and they will work much better in the future if they stay with their mates.

[Joe L.]

Re: Question on Replacing Valve Stem Seals on 350 Small Block

Thanks. The Felpro engine gasket set did not come with the sleeves mentioned.

Joe, The heads are still onthe engine. Since it has relatively low miles on the engine, we are replacing engine seals that can be replaced ...including the valve stem seals. It seems to be your step #2 that is the problem, i.e, trying to compress far enough to get the stem seal in it's groove.

Roger

Roger-------


In order to install the seals the valve springs must be compressed while the valves are in the completely closed condition. The best way to do this is by using an adapter in the spark plug fitting and applying compressed air to the cylinder during the entire valve seal replacement on each cylinder. The valves MUST be completely against their seats. If they are not, you'll never be able to get the seals installed.

Using a lever-type tool you should be able to compress the springs enough to install the seals. I've done it many times this way. I use the K-D #912 tool. I purchased this tool about 45 years ago, but this exact same tool is still available today. It's pictured below:


DSCN3030.jpgDSCN3031.jpg

[Roger D.]

Re: Question on Replacing Valve Stem Seals on 350 Small Block

I have just discovered this is 2014 and a wonderful thing called the Internet exists.
I Googled "Chevrolet Small Block valve stem seals" There were just an amazing amount of results in no time at all. Try it and you can chose your own. Here is a start:

https://www.youtube.com/watch?v=OsGqmOQus6Y

Edit add:

When removing the push rods and rocker arms keep them in the same positions they came from so that you can reinstall them in the same location. Those parts have been intimate for a long time and they will work much better in the future if they stay with their mates.

Thanks Terry. Nice video. Looks like what I'm missing is a good valve spring compressor tool. The one in the video looks like it does the job well. Also, we are making sure that everything goes back in the same place. Thanks for that reminder.

My engine does not have the umbrella type seals that were shown, just the O-ring seals. To use the umbrella type seals requires a machine shop to machine the bases where the valve stem goes into the head, right?

Roger

[Roger D.]

Re: Question on Replacing Valve Stem Seals on 350 Small Block

Roger-------


In order to install the seals the valve springs must be compressed while the valves are in the completely closed condition. The best way to do this is by using an adapter in the spark plug fitting and applying compressed air to the cylinder during the entire valve seal replacement on each cylinder. The valves MUST be completely against their seats. If they are not, you'll never be able to get the seals installed.

Using a lever-type tool you should be able to compress the springs enough to install the seals. I've done it many times this way. I use the K-D #912 tool. I purchased this tool about 45 years ago, but this exact same tool is still available today. It's pictured below:


[ATTACH=CONFIG]54631[/ATTACH][ATTACH=CONFIG]54632[/ATTACH]

Joe, thanks alot for the detailed info. I'm going to see if I can find more info on that tool.

Roger

[Joe L.]

Re: Question on Replacing Valve Stem Seals on 350 Small Block

My engine does not have the umbrella type seals that were shown, just the O-ring seals. To use the umbrella type seals requires a machine shop to machine the bases where the valve stem goes into the head, right?

Roger

Roger------


Small blocks of your vintage used only the o-ring seals. Umbrella type seals can be used with no valve guide boss machining. Positive-type seals MAY require valve guide machining depending on the type of positive seals used. This is determined by matching the OD of the valve guide bosses to the seal size. In general, I don't know of any all-Teflon type seals (i.e. "Perfect Circle Seals") that work with stock valve guides, but there may be some out there. Viton or Viton-Teflon positive seals are definitely available to work with stock valve guide bosses.

However, in general, if the engine is in good condition, the stock type o-ring seals will work well. One needs to be aware, though, that these seals are part of a SYSTEM which includes the stock-type valve caps (retainers) AND the shields. Do not think that you can "leave out" these shields (as some folks may advise) and expect satisfactory oil control. You can only leave out the shields if you go to an umbrella or positive type seal and, even then, I don't advise it. Folks who go to larger valve springs, which I DEFINITELY DO NOT RECOMMEND for a street engine, usually have to eliminate the shields because I know of none that will fit larger OD valve springs.

[Joe L.]

Re: Question on Replacing Valve Stem Seals on 350 Small Block

Joe, thanks alot for the detailed info. I'm going to see if I can find more info on that tool.

Roger

Roger------



The tool used in the You Tube video is much more convenient than the lever-type tool I use. I don't think that style tool was even available way back when I bought my tool. However, that type tool is also a lot more expensive than the lever type tool. For a tool that you use only once or twice in your life, it might not justify the expense. Such a tool might be available for rent, though.

[Terry M.]

Re: Question on Replacing Valve Stem Seals on 350 Small Block

Thanks Terry. Nice video. Looks like what I'm missing is a good valve spring compressor tool. The one in the video looks like it does the job well. Also, we are making sure that everything goes back in the same place. Thanks for that reminder.

My engine does not have the umbrella type seals that were shown, just the O-ring seals. To use the umbrella type seals requires a machine shop to machine the bases where the valve stem goes into the head, right?

Roger

Roger,
Please note there are other videos showing valve stem seal installation using the search terms I suggested. I suspect with a little more Internet searching you will find other valve spring compressors and styles of seals shown. I have neither the time nor inclination nor skill to critique their content nor that of the one I posted for suitability for your application. THAT is your job to do your due diligence. Remember it IS the Internet, so everything posted Is true -- Right?

I am simply trying to point you to where you can find the knowledge you seek. To pick and choose among the many options available is your task.

Edit add:
The valve spring compressor that is in my tool box is the same KD tool Joe Lucia posted the photos of. It has worked for both Big Blocks and Small blocks of the Gen I era. The only application I had trouble with was a 454 in a 1978 Suburban. Number 8 cylinder was imposable due to AC equipment interference. I had to use a valve spring compressor that more closely resembled a gear puller to get those last two springs off. I think the one that fellow uses in the video link I provided would have worked for me in that application, but it looks more expensive than the one I used. I must say I did admire that one he had. (Is it perverse to admire someone else's tools? Can I say that here?) I had never seen that style before. It looks like it might also work for the LS series engines, and that would be an advantage for someone who needed broad application tool, but I take it that is not your situation.

I have almost always worked on engines that I was reasonable sure were last assembled by the UAW and so I replaced the valve stem seals with products from the manufacturer's supply sources -- that is Chevrolet or the appropriate GM dealer's parts department. I have been blessed in not having to do any of this work since GM prostituted their parts supplies. I am not sure what I would do for engine parts now days. Such choices are now a lot more problematic than they used to be.

[Roger D.]

Re: Question on Replacing Valve Stem Seals on 350 Small Block

Thanks folks for all the help. I really appreciate it. With all of the info provided it's on to the task at hand and see how it comes out.

Roger