Valve stem seal install for 292 inline 6 - cup style

[Asshat]

I picked these up today, however, there’s only six of the cup style and twelve of the washer style.

I presume the cups go on the intake valves, but do the black washer ones go on there too?

Need an expert here.

[Asshat]

According to this, the Positive Intake seal is not used prior to 1981.

Can anyone confirm?

[Asshat]

Anyone have experience here?

[SkinnyG]

The positive seal needs the valve stem boss machined to accept it. They are a good seal, and if the head was disassembled, pay the man to get them machined to fit.

In the bad old days, they were only used on the intakes. I'd run them on all valves if I could.

The O-Ring was GM's standard oil seal, make sure you use the tin shield that goes under the valve spring retainer as well.

I run both the O-Ring AND the Umbrella Seal together for the best combination of mediocre seals.

[Asshat]

Checking valve guide clearance is critical too. Getting just the right amount of “wiggle”.
Maximum 0.001?

[SkinnyG]

Maximum depends how long you want it to last. 0.001" would be on the tight end of good - check the specs. Off the top of my head I think max allowable is 0.0033" but I'm likely wrong.

I took some heads to a local machine shop to have new guides installed and the seats cut (the seat cutter references the guide). I had measured between 0.0045" and 0.006" clearance; I wanted this engine bang on and didn't want to be re-doing the heads in 5 to 10 years.

They have them back to me, seats cut DEEP, and said "the guides were cherry - we didn't even measure them; we wiggled them and they're great." I was SO angry. Still am.

[Asshat]

Originally Posted by SkinnyG

Maximum depends how long you want it to last. 0.001" would be on the tight end of good - check the specs. Off the top of my head I think max allowable is 0.0033" but I'm likely wrong.

I took some heads to a local machine shop to have new guides installed and the seats cut (the seat cutter references the guide). I had measured between 0.0045" and 0.006" clearance; I wanted this engine bang on and didn't want to be re-doing the heads in 5 to 10 years.

They have them back to me, seats cut DEEP, and said "the guides were cherry - we didn't even measure them; we wiggled them and they're great." I was SO angry. Still am.

I get it, I’d be pissed too.
Not easy finding a good machine shop. Had a referral from a friend for a shop down in San Clemente, turns out the guy is closing his doors in a month. Drat!

[Steeveedee]

Originally Posted by SkinnyG

Maximum depends how long you want it to last. 0.001" would be on the tight end of good - check the specs. Off the top of my head I think max allowable is 0.0033" but I'm likely wrong.

I took some heads to a local machine shop to have new guides installed and the seats cut (the seat cutter references the guide). I had measured between 0.0045" and 0.006" clearance; I wanted this engine bang on and didn't want to be re-doing the heads in 5 to 10 years.

They have them back to me, seats cut DEEP, and said "the guides were cherry - we didn't even measure them; we wiggled them and they're great." I was SO angry. Still am.

That's one sorry valve job right there. Sink the valves? This ain't a VW! [/VW joke] I'd be telling my friends where NOT to go for a valve job.

George- I'm curious as to what you want with this engine. The amount of smoke out of the valve cover and exhaust is indicative of worn rings, no matter what the compression was. If you can get the smoke down to a tolerable level with valve seals, that's OK. But personally, I'd be at it a little more thoroughly. I see that you have the engine out, with the head off. How much of a ring ridge is there? You might be able to get away with cutting that back and honing the cylinders. Do you have micrometers to measure the crank for eccentricity?

[Asshat]

Originally Posted by Steeveedee

That's one sorry valve job right there. Sink the valves? This ain't a VW! [/VW joke] I'd be telling my friends where NOT to go for a valve job.

George- I'm curious as to what you want with this engine. The amount of smoke out of the valve cover and exhaust is indicative of worn rings, no matter what the compression was. If you can get the smoke down to a tolerable level with valve seals, that's OK. But personally, I'd be at it a little more thoroughly. I see that you have the engine out, with the head off. How much of a ring ridge is there? You might be able to get away with cutting that back and honing the cylinders. Do you have micrometers to measure the crank for eccentricity?

Hey Steve - I can get micrometers, but I wasn’t planning on removing the crank. Removed the pistons already, just going to hone and do new rings.
Worst case, I get a big block.

[geezer#99]

Looking at your other thread I’d bet you can catch a finger nail on that ridge in the bores.
If so honing won’t clean it up.
Needs bored.

[Asshat]

more pics - these are with the valve in the head and the keeper on the retainer. I don't see how the seal does any good if it is in the 2nd groove. It is nowhere near the valve guide where the oil would seep through.

[SkinnyG]

You compress the spring and retainer, then install the o-ring and the keepers. The o-ring goes INSIDE the retainer.

I've found the o-rings to be a one-shot deal. If you screw up and have to bust them apart again, they often get screwed.

Run the umbrellas as well. Those guide bosses are not for the positive seal ones.

[Asshat]

Originally Posted by SkinnyG

You compress the spring and retainer, then install the o-ring and the keepers. The o-ring goes INSIDE the retainer.

I've found the o-rings to be a one-shot deal. If you screw up and have to bust them apart again, they often get screwed.

Run the umbrellas as well. Those guide bosses are not for the positive seal ones.

I still cannot understand what the oring washers does in the groove below the retainer. What is its purpose? I can see the umbrella style covering the boss, that makes sense.

You mean these?

[Asshat]

And, what is the purpose of the shield? What does it do?

[SkinnyG]

The o-ring goes BETWEEN the retainer and the keepers.

Compress the spring/shield/retainer (with umbrella seal sitting inside), install o-ring, install keepers, release spring compressor.

The shield "shields" oil dribble from getting on the exposed valve guide.

The o-ring "seals" any oil from coming through the split keepers and down the stem into the guide.

Adding umbrella seals as well adds an extra helping hand of oil sealing.

[Asshat]

Originally Posted by SkinnyG

The o-ring goes BETWEEN the retainer and the keepers.

Compress the spring/shield/retainer (with umbrella seal sitting inside), install o-ring, install keepers, release spring compressor.

The shield "shields" oil dribble from getting on the exposed valve guide.

The o-ring "seals" any oil from coming through the split keepers and down the stem into the guide.

Adding umbrella seals as well adds an extra helping hand of oil sealing.

Ok, now it’s making more sense, thanks for that added explanation.

[Asshat]

Wanted to confirm Intake vs Exhaust valves. The exhaust valves have a thicker retainer, correct?

[SkinnyG]

Correct. They rotate the exhaust valve to reduce burning.

They are heavy, and are often removed in a performance application, but sometimes GM has used different height springs to account for the rotator thickness, or deeper spring seats in the head to account for the rotator thickness.

For a street vehicle, I'd leave them in (though I removed them on my daily).

[Happy_dan]

Just an FYI. I am doing mine now. It seems the exhaust valve stems are slightly shorter than my intakes to make up for the rotator retainers. My springs are all the same size. I put the head on a bench and pulled all the valves up tight. Put a straight edge across the top and the intakes are slightly higher.

[Asshat]

Originally Posted by Happy_dan

Just an FYI. I am doing mine now. It seems the exhaust valve stems are slightly shorter than my intakes to make up for the rotator retainers. My springs are all the same size. I put the head on a bench and pulled all the valves up tight. Put a straight edge across the top and the intakes are slightly higher.

Any pics to illustrate this?

[SkinnyG]

I assume you have the large valves in the large holes, and the small valves in the small holes? (I teach mechanics - I see a lot of stuff).

[Happy_dan]

LOL, yes on the large and small holes. I don't know anything about mechanics but I stayed at a Holiday Inn before the shutdown.

I should note this is a 1968 C-20 with a 327. Just happened to see this thread when searching for retainers to get my answers.

I hope this shows it. Slight gap between straight edge and top of exhaust stems.

[SkinnyG]

If the spring seats in the head are the same height intake and exhaust (that is, the exhaust is not cut deeper), I'd guess the valve is longer to account for the thicker rotator. I'd be inclined to ignore it and carry on.

Installed height of the spring matters more.