valve stem seals and guides

[Tscott38]

Are valve stem seals supposed to fit snugly over the guides?  I took one of mine off and the existing seal was 13/16" diameter on the inside and the guide is 5/8" diameter on the outside.  It fit right down over the guide but was very loose.  Is this the way they are supposed to be?  When I called around trying to get a new set of seals, the guy asked if the engine had been rebuilt and what the diameter of the guide and the valve stem were.  That's what caused me to ask.  Could this be a reason for burning oil, or is this the way they are supposed to fit?  This was an intake valve I took off.  Haven't got to the exhausts yet.   I hear they are a different design.   

[Chryco Psycho]

depends on the type of seals used , Most intake  seals are tight fit as they have vacuum below & less heat & generally need less oil , the exhaust can be umbrella type seals to deflect the oil away from the guide or can be tight fit as well , the exhaust guides are fit looser for heat expansion & provide slightly more oiling

[heyoldguy]

It sounds like you have the old style umbrella valve seals. That is the way that style seal is designed to fit and yes it could cause some oil consumption. There are replacement seals that will be snug on the guide and valve stem.

[Tscott38]

I just started looking around for replacement seals and the ones (non-umbrella for intakes) I see are all .500 inch diameter - my guides are 5/8 (.625").  Every one I see is like this.  The tech rep at Summitt racing  implied that I might have to machine the guides for the seals to fit - that seems crazy though.  Is .625" for the guide diameter normal on 915 heads? Any suggestions on places that carry a lot of guide sizes?  I thought this was going to be an easy job. 

I have an oil consumption issue and am trying for a snug fit on the intakes if that what was the original design.  Thanks for the replies though.

[heyoldguy]

Go to your auto parts store and ask for Fereral Mogul/Sealed Power Part# ST-2002

[Tscott38]

Wow - thanks. I did and they had it in stock.  They are going to be a snug fit, but Federal Mogul's info sheet says they will work.  My regular NAPA store couldn't find a 440 motor in their system - I'm done with them.   

I still could not find a regular parts store online that would give info on guide diameters and such.  SummitRacing was useless.  Jeg's had one, but still wouldn't give sizes.  Well thanks anyways.   

[heyoldguy]

That's too bad about your NAPA store. My NAPA store worked with me for about an hour to help find that part number for YOU.

[Tscott38]

heyoldguy - Well thanks you very much.  You went to a lot more trouble than I would have thought and it is appreciated.  They fit.  Now all I've got to do is get that valve out of the cylinder.  The magnet didn't work.  I'm going to pull the intake off now and see about how a pair of needle nose pliers will do. 

[bobs66440]