289 valve stem seals

[red66]

For a re-build, is it recommended to stay with the umbrella design deflector shields or go to a positive seal?  I have been told that it may be difficult to find a positive seal in the size needed for the K-heads.

[1967 eight barrel]

Positive type seals are always wise.  They aren't difficult to obtain either. The umbrella style tend to dry out over time and come apart. We poor FE guys used to wind up with a blocked return in the head from the pieces.
                                                                                         -Keith

[sg66]

Positive style and never worry about them again. Even if you need to have head machined for them to fit, once the engine is buttoned up you'll never see them

[gt350hr]

     As Keith mentioned , the original style rubber umbrellas harden and break apart. This can lead to blocked oil drains and in the worst case , jamming the oil pump. There are at least five different designs of positive seals. Nylon , Viton , silicone rubber , metal bodies with rubber or nylon inserts. They all do a better job than umbrella seals.
    Randy

[red66]

Thanks guys.  The guy working on my engine is having trouble locating posi locks in the size needed and is hesitant to machine the block.  I am hoping we can find a way to use the positive seals vs the umbrella seals.

[SFM66H]

Does anyone here subscribe to the belief that the springs should be removed from positive seal EXHAUST valve seals when used on cast iron heads, because they get hotter (and need more oil) than the intake valves?

[pbf777]

Does anyone here subscribe to the belief that the springs should be removed from positive seal EXHAUST valve seals when used on cast iron heads, because they get hotter (and need more oil) than the intake valves?

     Your question presents valid points, but isn't what is practiced as a norm particularly for "street" applications; therefore in the narrow context of the inquiry some misdirection may be instituted.  If I were to assume that this practice were established as productive, in a specific instance, then it would probably also indicate the practice of operating with relatively tight exhaust valve stem to guide clearances, to the point of regulating oil transition to the port runner, and thereby to a great degree negating the requirement of a seal function.  This is not uncommon in racing applications were the builder/racer feels the striction created by the upper "spring" is imparting a frictional resistance value with the motion of the valve; and is somewhat more feasible with the iron castings verses aluminum as it (iron) is generally more stable with heat expansion and exhibits less difficulties with the displacement of the position of the guide and seat locations; and particularly popular in the limited classes of racing requiring the use of iron cylinder heads, and the competitor is seeking every possible advantage, no matter how small.     

     Scott.

[shelbydoug]

This simply is not a concern. What you are asking about would be for an ultimate high rpm endurance engine.

First off, you would be using the wrong head. These are production heads and you will find that there is a special casting for the factory comp cars called a GT40 head. Even so, the era in which those cars raced the technology that you speak of hand not yet arrived. Even if it had, the design of that head being based off of a production design would have been as Ferrari stated,  for "an irrigation engine".

The best that you can do, and all that you need to do is change out the complete cast iron valve guide for the current version of bronze that is currently used in aftermarket aluminum heads like Edelbrock, AFR, or take your pick.

There are several variations of "positive valve guide seals" available and all are just as good as the other. I still use the Teflon ones but they are available in viton and other materials. Most exist simply from preferential engineering specifications from one of the major car manufacturers. Any will do the job.

They are all minimum in size and usually fit right onto the already precut bronze valve guides but if you want to stay with the original integral iron guides cast into the head, all you do is a very simple and easy cutting/machining down of the guide with an inexpensive carbide bit supplied by the seal manufacturer. All you need is a competent drill and even an 18volt Ryobi will do the job.

You also need to consider which valves you are using. If you are switching to current stainless, they are all a much higher quality alloy then ever existed back then in "the day".

I understand the concern that prompted the question but it really is a good example of way over engineering a project. All you are attempting to do is put lipstick on a pig. Be my guest but it's still just a pig. 

Have you ever seen lipstick on a pig? Yuck!   

[sg66]

Been away for the weekend and knew I had these pics. Crane 99820 is what I used 30 years ago and to this day have had no issues. You do need to machine the head slightly for them to fit but once they are done, you never see them. I don't recall that there were any available back then either that would fit without machining. https://www.summitracing.com/parts/crn-99820-16

[Dizzy]

Only my 2 cents,but most every collector car rebuild will not see many miles of use. The stock "umbrella" style seals satisfied millions of applications for billions of miles ( check my math ) I realize some just like to spend money at the machine shop to get a bill that proves something,but in reality ,the engineers back then had 50 K warranty to contend with and properly designed those to meet most street applications. You can try to re-engineer this area ,but for what reason? Those PC style seals are not fool-proof.I just replaced a set on my EZGO golf cart......

[gt350hr]

 The entire automotive industry has migrated to valve stem seals that press onto the valve guide in some fashion. While rubber umbrella seals "were" the norm , time marches on.

[SFM66H]

Randy,

What are your thoughts on the practice of some to remove the springs from positive seals on the exhaust valves (only) because it is believed that they 'need more oil' because they get hotter?

What is/could be, the result of doing so?

Thanks,
Kieth

[427heaven]

I try to put my engine builds into perspective, of what my goals are to be for any given project. All answers here are correct... Some people refuse to go with more modern, better technology engine components. The cost to freshen an engine with GOOD parts is not much more than old style technology. If you have a 150,000 car and you want to install 35.00 sub par components its well and fine for the guy that doesn't understand there are better parts available. Old will work fine for the average engine but if you feel like having a SPIRITED drive that's the one time you will be pissed off when an engine failure will occur. We used to get out and hand crank our cars to start them, but we learned there are better ways of doing things.

[gt350hr]

   Keith,
      I'm not tied to "one" specific type or brand of seal "these days". "Back in the day" when it was rubber umbrellas OR PC seals only , I installed the intake seals carefully using the plastic sleeve and on the exhaust , I simply jammed them on or put on used intake seals . This would allow small amounts of oil to "get by" and oil the guide. Doing this also left a dark "streak" from the guide on the top of the exhaust port so I stopped doing that and used the sleeve when installing exhaust seals. I saw no difference in valve stem wear or valve guide wear but my exhaust ports lost the oil streak. I still use PC style seals , but also use the newer Viton material seals which do nut have a spring at the top as well as some of the metal clad seals which use a "garter" style spring at the top. I would not remove the spring from a white nylon PC seal for the exhaust.
       Randy

[SFM66H]

Okay, Thanks Randy, and to all who took the time to reply, I appreciate your insights.

Kieth