73StreetRace

I would like to replace my old valve stem seals.
Before ordering, I need to know the valve stem diameter and the valve guide diameter. The heads are bone stock, I have a SB 350, year is 1973, manual transmission.
Maybe I will buy aluminum heads next year, so I don't want to spend too many bucks on them... but I know valve stem seals are cheap.
I don't want to remove the heads. No blue smoke on acceleration, very little on startup, more on deceleration. The plugs do not oil foul, compression test is OK, but I noticed some oil on spark plug threads in cylinders #7 and #8 if I let the car sit for a few days.

Oil pump is new and oil pressure higher ( 40-65 PSI hot ),
Oil level is at max on the dipstick,
Oil weight is 20W40 ( synthetic ),
I have two breathers on valve covers ( no more PCV ), if anything has any possible influence ???

Other questions :
Do I need to replace the valve keepers too.
Recommendations about seals : Viton, umbrella, O-ring ( but no machine work ) ?

73StreetRace

I ckecked the valve stem diameter after work. It's 11/32".
I still need to know the valve guide diameter, if somebone knows

I removed a valve cover and took a picture of the seals ( two different angles ) :

midyearvette

your guides have been machined for the rubber type push on positive seals.....the 11/32 should fit but you may not know till you take off a spring and measure the guide od......are your springs in up side down?? or is this something new from comp cams?? they look like bee hives to me.....

Solid LT1

Unless your valve guides have been machined for rubber seals, the factory Chevy seal is an O-ring and steel shield under the spring retainer. The 260/289 Ford motor had 11/32 diameter umbrella style seals that usually fit a stock Chevy cylinder head and can be sourced at a local automotive machine shop (the machine shop would probably give you the Chevy O-rings that come in every complete gasket set and are never used in a quality rebuild.)

73StreetRace

Thanks for your help ! Don't know about the springs, when I bought the car 20 years ago, they were just like this, I never removed them
Do you mean the guides were not machined by GM at the factory ?

midyearvette

gm did machine some guides but i dont know when they started doing so...usually they were not machined and used a small o ring on the valve stem just below the keepers...i think if you ordered the 11/32 rubber seals, not the nylon's, it would be ok but not positive until you pull a spring....i think you have big block springs, beehive , that are up side down.....maybe it's the picture??..or maybe some old racers trick??....

73StreetRace

Thanks ! I think I will first take off a spring before buying anything ( except a valve spring compressor ) and see what I have beneath...

Maybe I could try some BARDAHL "NO SMOKE" meanwhile...

GUSTO14

Your seals sure look a lot like the PC teflon seals that have been around for many years. If that is the case, the guides have been machined to accept them. Once you remove a spring you'll get a better picture of them.


If you have PC's you can get them from most good speed shops or go here and order them...
http://www.competitionproducts.com/products.asp?dept=45

Some will tell you these are best used on race motors as they do a better than average job and on a street engine you want a bit of oil to lube the guides. For a street engine these might be a better choice,

Viton Valve Seals, 11/32", Set of 16 $14.95 They will fit most stock valve guides.
http://www.competitionproducts.com/p...p?number=S5325

Good luck... GUSTO

midyearvette

i clearly see the black viton seals in my picture

73StreetRace

Thanks for the infos, guys
I think I'll have a look at my springs again. I had never noticed that they could be not cylindrical...
Looking at the pictures I took yesterday, I'm not sure either. I'll take a measurement with a caliper.

Solid LT1

I guess I wasn't paying attention, great photos of your motor. It looks to me like you have teflon style valve stem seals already, I would switch to the viton rubber style seals like the one poster listed. Your guides appear to have already been machined, if you live in a big enough town it should be no trouble to locate a automotive machine shop to help get you the correct sized valve seals to fit on your guides. It also appears to me that you have the special tapered springs to fit into the stock diameter sping seat of a production cylinder head (big diameter at the retainer, smaller at the spring seat, kind of like a reverse Behive spring), you may want to take these along when you go to the machine shop. I have used "air chuck" valve retention and the old "shadetree" stuff a nylon rope through the spark plug hole and bring the piston to TDC methods, either works OK but, if your valve seats are leaky, the rope method may work better for you. You are taking on one of my least favored jobs in motor maintenance, have fun!

73StreetRace

It was also my first opinion when I looked at the enlarged photos. The seal looks like black rubber with a small white teflon insert in the middle, but no visible metal part outside...

Manuel Azevedo

By the look in the picture you have a non stock setup there, those are neopren (spelling!)seals with a teflon insert. I would not use that style at all, use an all neopren type as some where pictured above. The stock OD of most stock guides will be .562 which appears to be what you have, but yea you should pull a seal frist to be sure. Also with out the stock metal shields in place I would not recomend a cup style seal but do use one that is clapped to the OD of the guide.

73StreetRace

I take notice of this good info.