Metal Body PC Seals On Stock Guides

[JedIEG]

Has anyone run a modern metal body positive seals on a stock guide? I was looking at these from Comp to try to control oil better on my dad's 360. The heads are not machined for smaller pc seals and he is currently using stock umbrella seals. I think 3/8 × 0.500 would be the right diameters for stock valves and guides.

https://www.compcams.com/3-8-x-500-metal-body-viton-valve-seal.html

 

[beanhead]

No. The guides 'should' be machined..but that said there's people that say they found a seal that could be crammed on without cutting.

 

[69Bee]

The 0.500" measurement is the outer diameter of the valve guide. The guide should be machined to 0.531" or 0.562" OD. Best would be to rebuild the heads, install 3/8" x 9/16" guides and cut all of what is left of the old guide down, give it a valve job, and then mill the heads. Use new valves and springs, and the seals (0.562") will fit right on properly.

 

[PRHeads]

For 11/32” and 3/8” valves, I usually cut them to .531”

 

[JedIEG]

The heads were rebuilt with new valves, hardware and milled when the engine was rebuilt, but I believe the guide where left stock. I think it has ~10k miles only, but it has always had oil control issues. We just refreshed the engine last winter with new rings and it is still having oil control issues. I am suspicion of the stem seals now and would like to try to eliminate that variable with PC seals. With the current situation, I need a PC seal that would fit without modify anything. I don't have a set of small block heads sitting around, so do you know what the stock guide diameter is?

 

[PRHeads]

Just be mindful that the steel jacketed seals have a pretty small window to go from “can’t get them to go on” to “ they won’t stay on”, since the steel jacket is a fixed size and doesn’t use any retaining device(like a spring band around the seal) like a “soft” seal would use.

I just checked a J head I have here....... on that head the guide OD ranges from .639 to .644

No idea how that would compare to your heads.

If you’re using the true “umbrella” type seals(they ride up and down with the valve), then I’d try the factory style positive seals........ if you can’t find any of the steel jacketed style that will fit.

 

[oldkimmer]

Personally I don’t like the seal that grips the outside of the guide. The valve stems seem to wear more/faster then become loose in the guide. Kim

 

[JedIEG]

The umbrella seal is not exactly a consistent oil control method so I would like a PC type with the spring around the valve. That's why all OEMs switched to them, and I think Chrysler may have switch to them in later years, just before releasing the magnum. Looking at Fel-pro they have a seal set SS 72730 that appears to be for the 90-92 la. Anyone know if the guides changed on the 302 or 308 heads?

 

[oldkimmer]

I’m not sure if the 302 and 308 heads did change or not. I have used the newer seals but only pushed them down to the guide. Once the engine turns over the find their place on the stem. But I’ve been told by a couple builders that’s the wrong way to do it. They say to put the seal as close to the top because that way the seal shards the oil over the guide better. Idk how true that is as I’ve never did it that way. Kim

 

[PRHeads]

I found a listing for an 89-92 360 using a steel jacketed seal.
The seal ID is shown as .627”