Inliners International Forums General Discussion Engines Valve stem seals for a 250 chevy

Hi again everyone, anyone know where i can get Umbrella valve stem seals for a chevy 250-6?
thanks,
Jason

I get them from a local machine shop,universal fit for 11/32 valve stems.Better auto parts stores should stock them,they were used on many Ford engines

If I am not mistaken you would not want to use Ford seals on a Chevy valves.Chevy valves are 5/16" dia. so the Ford Seals would be to big.The ones for a Chevy V motor should work. Paul

Being you have a used motor I would also replace the "O" rings on the valve stems..that way you get a "double dip"...Every little bit helps.....SCRAP

Dear Jayson;

The umbrella seals work really well on old engines, but too good for heads with new guides.

If your changing them with head on, okay.

If your doing a valve job with new guides use the 'O-rings'.

Good luck, John M., #3370.....

John,

I beg to differ with you on your response to the valve seals.

I do dozens of heads a week, using new bronze guides, and I ALWAYS use a positive style valve stem seal. Very seldon do we use the old style umbrellas anymore, and the o-rings go straight to the garbage barrel.

As long as the shop is not using old stone age style stones to do their valve jobs, and are replacing the guides with quality ones, and they have and also know how to use a runout gauge to check vale seat concentricity, you should use a positive style valve seal.

The only reason most people, and shops still use o-rings and umbrellas, is because of the lack of quality in their work. With unacceptable runout on the seats, and shops still knurling valve guides, they can't use a good quality seal, because they would seize the valves.

I typically run .001 - .0015" intake guide to valve stem cleanance, and .0015 - .002" on the exhaust. I always check the runout on my seats, and they never go past .001"

If 64belair is installing the seals on a motor w/ miles on it, go ahead and use the umbrellas, it will help reduce your oil comsumption down threw the guides. If the head is a freshly rebuilt unit, consult the machine shop that did your work first, but I'm sure they will tell you to use the umbrellas also.

Good Luck,

Ken

www.CustomDesignPerformance.com

Dear Jayson;

This is one of those times where there is more that one "right answer".

Using bronze guides is a 'high end' procedure and far better than what GM used in 1963.

However; An engine for a passenger car use will not need all of this effort & expense to function well and for this application a new OER valve, guide or O-Ring will work just fine.

You see the umbrella seal (Ford or GM) covers the guide completely, shielding it from the 'splashing oil', which is good for old/worn guides and saves the expense of knurling or replacing them for the customer.

For a 'precision engine' this is NOT acceptable as Ken states and the generaly used "just fix it" procedures are obsolete there.

Ken's customers demand this, because their (L-6) engines produce 700-1,000 Hp. which is several times what GM had in mind for the 250.

JM.....

well rebuilding the old guides with bronze walls is cheaper them putting in new cast iron guides. and if you are doing a job you mite as well do it right as half way. it cost no more in the long run.
i agree with ken on everything but the remark about using stones. i use stones and hold the runout to less then .001. i do all types of heads proformance heads for ford-chevy small blocks. inlines tractors.