[DeTomaso] Valve Stem seal and Keeper replacement

[Tomas Gunnarsson]

Thanks for the input. I have sleeved guides for all valves, I assume it's bronze guides. I'm running SS valves but have no idea what the clearance is. The intake guides have been in use for tens of thousands of miles with umbrella style seals before I installed the new valves and teflon seals. The exhaust sleeves were run one summer (~2000 miles) without any seals at all before I installed the teflon seals. I installed them because the car would "puff" smoke on starts. My head rebuilder had told me to run without exhaust seals.

Tomas
  ----- Original Message ----- 
  From: GR2835 at comcast.net 
  To: Tomas Gunnarsson 
  Sent: Sunday, August 09, 2009 4:30 PM
  Subject: Re: [DeTomaso] Valve Stem seal and Keeper replacement


  Hi,

     I just went through hell with teflon seals after 2200 miles. The stock cleveland  heads had iron guides that were totally destroyed along with the valve seats. It seems that teflon seals don't allow enough oil through to properly lubricate iron guides and may only be used with bronze guides and loose stainless valves (.ooo2) . If you have aluminum heads you don't have the same expansion problems.

       grinillinois


  ..----- Original Message -----
  From: "Tomas Gunnarsson" <guson at home.se>
  To: detomaso at realbig.com
  Sent: Sunday, August 9, 2009 5:39:03 AM GMT -06:00 US/Canada Central
  Subject: Re: [DeTomaso] Valve Stem seal and Keeper replacement

  Asa Jay,

  I've done this a couple of times myself when changing springs and/or seals. I never bothered bringing the engine to TDC, instead I let it turn over to BDC which is a stable position. Like you I found my seals very hard though not quite as messed up as yours. Allmost all of the exhaust seals had cracked IIRC, some of the intakes had too. I went with teflon seals that require machining when I had the heads refurbished, it'll be interesting to see how they hold up.

  Tomas

  ----- Original Message ----- 
  From: "Asa Jay Laughton" <asajay at asajay.com>
  To: <detomaso at realbig.com>
  Sent: Sunday, August 09, 2009 2:39 AM
  Subject: [DeTomaso] Valve Stem seal and Keeper replacement


  > Based on a recommendation from Dan Jones (our favorite 351C engineer 
  > type), I purchased some new Comp Cams keepers for the valve stems on my 
  > engine.  I plan to run the engine basically stock in the Silver State 
  > Classic Challenge.  Dan has told me the stock valve stems and keepers 
  > can separate after long use, and possibly at high rpm.  I don't plan on 
  > any blazing speeds like Mad Dog but I do plan on triple digits.  So I 
  > felt it prudent to take Dan up on his suggestion.  While in there, I 
  > figured I'd change valve stem seals too, as I've rebuilt other 351C's 
  > and found nothing left of the original seals.
  > 
  > To do the job, I used a compression tester that had an air hose nipple.  
  > After removing the shrader valve from the hose and screwing the hose 
  > into the cylinder, I dialed my shop air to about 65 psi.  Before hooking 
  > the compression tester hose to shop air, I cranked the engine to TDC on 
  > #5 and using a wire, verified the piston was near the top.  The air 
  > keeps the valves seated while using a spring compressor to remove the 
  > springs.  I discovered higher air pressure spun the engine over, but at 
  > 65, the piston stayed put and the valves stayed closed.
  > 
  > The seals and keepers are replace one valve at a time.  Do everything on 
  > one, then do the other.  Then move to the next cylinder.  I started on 
  > cylinder number 5, drivers side, front.  Both the intake and exhaust 
  > seals were intact and looked rather good, except they were hard as a 
  > rock.  I replaced them both with new seals sourced from Napa.  These are 
  > stock type seals, not positive lock seals.  I didn't want to mess with 
  > machining the guides, especially as the valves are still installed.  
  > After installing the new keepers, I moved on.  When I got to number 6, 
  > things changed.  I started finding really toasted seals.
  > 
  > It took a few hours, changing everything on one cylinder, then removing 
  > the air, rotating the engine, verifying the cylinder I was at was on 
  > TDC, installing air, compressing springs, changing seals and keepers, 
  > replacing springs and moving on.  Repeat seven times.
  > 
  > It was a darn worthwhile job and I'm very glad I did it.  You'll see why 
  > when you check out the photos and more comments here:
  > http://www.teampanteraracing.com/index.php?option=com_g2bridge&view=gallery&Itemid=57&g2_itemId=2951
  > 
  > Now I have to clean up the valve covers, do some cleaning and vacuuming 
  > in the heads, torque all the rockers back in place and put the valve 
  > covers on.  Darn near done.
  > 
  > Asa Jay
  > 
  > Asa Jay Laughton, MSgt, USAFR, Retired
  > 
  > & Shelley Marie
  > Spokane, WA
  > 
  > 1971 Mach I Mustang  [ASA JAY]
  > 1973 Pantera L 5533  [ASASCAT]
  >    
  > ******************************     
  > http://www.asajay.com
  > http://www.teampanteraracing.com
  >  
  > 
  > 
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