What do you folks prefer for valve stem seals? Application is a stock 1969 455 D-heads.
Thanks

 

I like the teflon seals, but you have to machine the guides for them to fit.

 

If you just want to do a simple repair, use the stock umbrella seals.

 

At this point the plan is just to freshen and reseal. Not thinking about having the tops of the guides machined. I guess that means stock type umbrella seals are my only option?

 

brain, you sound like you think there is a problem with using the umbrella seals. The umbrella seals sold today as replacements (Felpro) are a hard teflon type material and not the old rubber type that fell apart with heat and age. I like the idea of lubricating the guides especially with stock valve stems and valve guides and use the shorter of the two on both intake and exhaust; actually on my last build I used them only on the intake, no seal on the exhaust. That is on an "E" block, "C" heads and the 308 degree early W30 cam. You probably would have more vacuum with the 455 so use them on both intake and exhaust. The only drawback with using the umbrellas is if you have dual valve springs which don't allow using them because of the larger diameter of the umbrella.

 

Like the others have said you really dont have much choice if you arent going to pull the heads and machine the guides. I cant say I have ever seen an Olds head with bad seals but every single one I have seen has had the hard Nylon umbrellas that just dont go bad.

 

Thanks for sharing your experiences. For this car, which is a low mileage original, seems like sticking with the umbrellas will be appropriate. I haven't assessed the engines health and determined if head removal is merited.

 

I no longer have a factory diameter valve stem cylinder head in my garage but I remember test fitting the late model Ford small block positive style valve stem seals and they worked. I would measure the OD of the valve stem and snag a set from Summit or even eBay.

 

You can install those valve stems seals by compressing nylon rope in the combustion chamber at TDC. You don't have to worry about a spark plug fitting and having compressed air. I did this on my granddad's Lincoln 20+ years ago. I'm sure there's a YouTube video now. Maybe that's something I should do to my 455 since I removed the rebuilt engine...

Let us know how the install goes!

 

I cleaned up a set of J heads for a beater 455 that I rebearinged. More than half the original umbrella seals were roasted, crumbling, and deformed. Valve guides were a bit sloppy too so I wanted to reduce oil consumption. I found the following viton positive style seals (Cometic CGT-3066V1-16) and they have a .010 interference on the .575” od of the uncut valve guide on the J heads. They bag says they are 11/32"X.563"x.470"x.690”. I was just under the valve covers recently after 2000 miles and they looked like they were doing fine. If you have something other than a stock cam and valve train you need to check for interference with the springs and when the valve is open.