Found some tiny rubber O rings laying in the top of the head when I had the rocker covers off last time. I guess their probably valve stem seals. Engine smokes quite a bit a start up and uses some oil. I've read a little bit about replacing them, would like to hear from anyone who has done this. I read something about they go on after the valve springs on a nailhead? Could someone explain the procedure for replacing them on this engine ('62 - 401) and do I need to pull the heads? I've read about replacing them with the heads on the engine using an adapter that screws into the spark plug hole that pressurizes the cylinder with an air compressor to keep the valves from falling down into the cylinder when the valve spring retainers and springs are removed. Also something called the "rope trick" where people cram rope into the cylinder through the spark plug hole and compress it with the piston. Sounds kind of odd to me. Nothing I've read though pertained to a Nailhead and would like any info from people who know and have worked on these engines. Thanks!
Buick didn't put valve guide seals on the Nailhead until 1966....and then they used them only on the intakes. The seals on your engine must have been put on by a previous owner or mechanic. To use the '66 valve guide seals, the top of the valve guide must be machined to accept them. I don't know if any other type of seal would be as effective as the original '66 type.
replacing them can be a pain in the butt on car but is not really all that involved. 1) removed rocker covers. 2) removed rocker shaft assemblies. 3) remove spark plugs now you are ready to get going. You will need an air compressor (not necessarily a big one) and an air line with a fitting that goes into the plug holes and seals (usualy an o'ring) 4)**A:'Fill' one cylinder with air then using a suitable valve spring compressor compress the spring for whichever valve you will be changing seals on, B:remove valve keepers and retainer. C:Release compressor tool slowly and then remove valve springs. D:Remove old seal. 5) reassemble in reverse order. **Finding an appropriate compressing tool for a shaft style rocker set up can be tough. I have one that 'grabs' the top and a lower portion of the spring then you 'screw' it tight to compress the spring and others that work but installing an 'bare' shaft on the stanchions and using leverage to compress the springs. Using an small pen type magnet to remove the keepers will help also. If you are pushing alot of oil out, check the valve to guide clearance before replacing the seals. you should have 'VERY' slight movement of the valve inside the guide, just enough so it won't bind/stick. If it moves alot, the guides need replacement or guide liners installed and the vlaves may or may not need to be replaced depending on wear. The rope trick MIGHT work but with the valves being on the 'top' of the heads and the sparkplug hole on the bottom, the hi dome of the piston would likely stop the rope from going where you want it under the valves. This would work much better with a flat top piston in another motor.
Thanks Joe; I'll have to check around for a spring compressor. Are those "O" rings the only seals or do the exhaust valves have 2? Think these seals are still available through NAPA?
The seals are definately still available from NAPA. I just got a set in this week. Victor list them and some one else does also-I just went with the Victor p/n. The eight intake seals were less than $10 my cost. Napa may also be able to get you the necessary compressor and air line adapter. The factory did not install seals on the exh but you could either have your guides machined to accept them or install new ones on the exh side which match/are listed for the intake side. Napa also still lists these guides. I just purchased exh guides also. Replacement of the guides will require the heads to be removed, and take a little ability to install. I have a tool/bit/adapter for the end of my 'air hammer' which fits the 3/8" ID of the guides and pushed them right out. Then, I freeze the new guides and heat the heads before installing the guides. Make sure to measure the heights of the orig guides before removing to make sure the replacement guides go back to the correct height.
Fyi Take it for what it's worth. Buick didn't think they were necissary. Me personally, I don't think it would hurt. Erik
that's an interesting service bulliten. :Brow: being the inquisitive p.i.t.a. that i am, on my old motor i could never figure out why it smoked on startup after sitting for less than a few hours. heads were just done, teflon seals on the intakes only. so then one day i shut down the hot engine, and pulled the intake manifold. with a flashlight, i peeked at the valve stems. i could see the oil running down the stems very slightly! i can only imagine the exhausts that i couldn't see dripping into the combustion chamber! so then i went to carmen's, and we machined the bronze exhaust guides for teflon seals too. then after a few months of testing, i concluded the problem became much better.....smoke was nearly gone, but still smoked just a little. :Smarty: now........the million dollar question..........are seals on exhausts a good idea from the perspective of guide wear? i think it's a bad idea........because pressure from exhaust would tend to force what little oil gets in there out anyway, causing early failure of the exhaust guides. when i did up my next motor, i only sealed the intakes. this motor smokes on hot startup now just like the old one did. let it smoke........i feel better knowing the guides have some oil. i also went with knurled cast guide sleeves this time. incidently........i ran bronze guides in those old heads, ran them for about 40,000 miles. when i took it apart before i got my new motor, they were still tight even with seals on all 16 guides. what does this prove? i don't know.........maybe that i just enjoy taking my motor apart ou: :laugh:
