The engine was blowing some smoke at startup when hot. Removed the valve covers. The engine did not have valve seals per se. What it has is a nylon thing that looks to serve as a deflector to deflect oil away from the seals. The valve guides all appear to be within spec. Now here is the thuoght as a fix to the smoke problem. We were going to try and find an umbrella type seal that would fit in between the double valve spring and use them in addition to these deflectors. Please comment on this thought process.
-
-
the nylon pieces are umbrella type seals
sounds like the GM setup. if the nylon pieces are still retained in the valve spring retainers umbrella seals should make no difference. -
Re: the nylon pieces are umbrella type seals
Clem -- thanks for the response. Yep we are also using the nylon deflectors. However we are only going to put the umbrella seals on the intake valves.Comment
-
Re: the nylon pieces are umbrella type seals
Clem I thought the GM seup used umbrella type seals which were rubber ?? These are definitely nylonComment
-
Re: the nylon pieces are umbrella type seals
the retainers for GM BBC springs # 3970627 use a nylon umbrella type oil shield which is fixed into the retainer.Comment
-
Re: the nylon pieces are umbrella type seals
Yep they are the ones -- they snap into the retainers. Now I am really stumped, do these seals wear out or just wear from the valve stem friction or hsrink due to age and tmeperature ??? Oil is getting down the guides somehow and the giudes appear to be in spec. Should I replace these nylon sealsas well ??????Comment
-
Re: the nylon pieces are umbrella type seals
you will have to buy new reatiners to get the seals. i do not believe anyone sells a rubber umbrella type seal for the dual springs because of their small inside diameter. every new BBC corvette,truck and car i owned never got more than 600/800 miles to the quart of oil. were the guides ever repaired with bronze wall because then you need a positive type of seal.Comment
-
Re: Valve Seals Help 66 427/425 opinion needed
John------
As clem mentioned, the valve caps with the nylon shield are the GM piece. They were not originally used for 1966 applications, though. I believe that 1966 applications used a traditional valve cap with a seperate, umbrella-type seal. This style seal was used through early 1969.
The GM style seal that you have can be retrofitted to earlier big block applications, though, and, apparently, that's what someone has done here. You can purchase replacement caps with the nylon shield under GM #3964264. Or, you can get the spring and cap kit under GM #3970627.
Personally, I consider the the GM cap and shield described above to be superior to the seperate cap and seal. However, you CANNOT use the GM cap/shield assembly with an ADDITIONAL seperate umbrella shield. The 2 will interfere with each other and destroy each other in the process.
You can also go to a seperate, POSITIVE style valve seal. Depending upon the type of seal you use, you may have to machine the top of the valve guides to accept these seals. If you use these seals, I recommend the use of no other seals or the GM style cap/shields you now have on the engine. None of these things are necessary or advisable with positive seals installed.In Appreciation of John HinckleyComment
-
Re: Valve Seals Help 66 427/425 opinion needed
Clem & Joe -- Thank you for your responses. I found a picture of the GM HP valve seals you both mentioned. They are not the seals that were in the engine. The seals that were in the car are the size of a lifesaver candy, maybe even a little smaller, and press into the retainer. In fact they even look like a lifesaver candy. We ended up finding a rubber umbrella seal that fit inside the inner valve spring and installed them on the intake side only. They have two wire spring retainers, one at top, one at bottom. The valve guides were the bronze spiral type. So far so good -- no smoke. We shall see -- once again thank you for your responses.Comment
Comment