In my adventures with the 84' restore I pulled the manifolds and noticed some of the exhuast ports were damp with oil/carbon and some of the plugs were very dark. I assume valve stem seals are failing so I want to replace them. What is a good seal to use the positive type? I read they may keep the guides to dry anyone have input on this?

 

I'm sure there are conflicting opinions on this, but I've used positive-lock seals on the intake and exhaust valves on every SBC head I've ever had redone....never had a valve seal issue or guide wear problem afterwards. The machine shop I worked in out of high-school a few decades ago, did and still does install the positive lock style on the heads of anyone who wants the best results and not the cheapest cost. We all know what happens to the little o-rings and umbrella type seals after enough heat cycles....they dry up, break apart and fall off. When I get a master gasket set, those go right in the garbage! Just my $0.02s worth! Good luck with whatever direction you choose👍

 

I see the Felpro posi seals still come with the stem O-rings wonder why?

 

To seal the retainer to the valve stem. It's important. You want to keep as much oil away from the top of the valve guide as possible. Particularly on the intake because the vacuum on the valve side of the guide will suck oil down the guide even with positive lock seals.

Here's some things to keep in mind regarding 'valve stem seals':

When the engine is running, exhaust pressure is positive. I'm not sure how helpful positive-lock stem seals are on the exhaust.
The o-ring seal seals the bottom of the retainer to the valve stem. Oil can't run out the bottom of the retainer, follow the valve stem and run past the guides (particularly exhaust) when the engine is not running. << This is what causes the smoke on start-up.
The "umbrellas" on the exhaust divert any oil that gets past the o-ring, or gets on the stem from splash when the engine is running away from the stem and valve guide.

The intakes benefit from positive-lock stem seals. But still install the o-rings.

Positive-lock seals reduce the retainer to guide clearance. If you are running 1.6 rockers, or non-stock camshaft with more lift than OEM, double-checking retainer to guide/stem seal clearance is a good idea.

I've done a bunch of V8 and V6-90 stem seal jobs using the GM kit that has the o-rings and 2 sets of exhaust umbrellas (there are two exhaust stem diameters for 5.7L) and positive-lock seals for the intakes. One of the engines I put the GM kit in was the 93 Typhoon that I owned for 26 years. I put stem seals in it shortly after purchase in 2000-ish (at about 80,000 miles) and it was not smoking on start up 23 years and 100k miles later when I sold it.

 

None of the newer heads run or have a spot for the Oring seal and most run Posi seals on intake and exhaust. Every head with some age seems like the Oring crumbed and fell into the oil which is why I'm not keen on installing them. Just seems redundant to include them with the better sealing posi seals of today.

 

So I jumped on the valve guide seals today I opted not to mess with the springs and rockers right now because I will likely swap the heads, cam and valve train after I confirm the engine runs well. I purchased two sets of Felpro posi seals and on set of umbrella's just in case the posi's did not fit. The engine is super clean inside only 60K miles and seems to have been maintained. The intake side had factory posi seals and o-rings and the exhaust side had umbrella's and o-rings. I used posi seals and O-rings on intake and exhaust they fit just fine on the exhaust side just like the intake. I used the o-rings because I had them and it can't hurt plus as I stated they will get pulled soon enough. Very easy job just a bit time consuming start to finish to 4 hours with the rocker covers already pulled using air and a crank **** compressor just need to adjust the rockers better.

 

It's been worked on. 1984s had o-rings only from the "factory"..

 

Anything is possible but everything seemed untouched. All the old O-rings where still in place mostly but crumbed when you touched them so they had age.