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THE LOBBY A gathering place. Introductions, sports, showin' off your ride, birthday-anniversary-milestone, achievements, family oriented humor. |
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#1
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Valve Seals
Hi All,
Spring is here and the TA is out and about! Several projects will be address this year, including new Oil Seals on the valves. Everything is fresh on the motor and only about 1,000 miles on it. When I had the heads off I put the umbrella type seals on the valves and I think I did it wrong so there are puffs of the old blue at deceleration etc... The famous Nunzi Romano did all the machine work on my motor, one of the last ones he did, and something is nagging in the back of my mind that he grooved the valves to accept the better Chevy seals? Not even sure what I look for, but what to replace and get the right things. Any info/help would be most appreciated. In case it's not in my Sig, she is a 1970-1/2 Trans Am, Ram Air 3 motor. Thanks in advance! |
#2
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Nunzi's son is a member here - maybe you could contact him to get your question forwarded to his dad. Look for tommy67.
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#3
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Amazing! Thank you so much for the help. Looking for him now.
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#4
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If there is a 2nd groove on the valve under where the valve retainer locks go, it is machined for the o-ring style seals. For an o-ring seal to work properly, you really need to be running the metal shields that go at the top of the spring and stock retainers if you use this style of seal. Your engine would have come with this style of seal from the factory. It sounds like you are running the Ford style umbrella seal that slips over the valve stem, some Chevys used them as well. The best option is probably the positive Viton oil seal that presses on the guide and fits tight over the valve guide. However, the heads would need to be machined for this type of seal. I would be willing to bet that Nunzi machined them for that style of seal. To verify, you can measure the top of your guide. It will likely be .500 or .530 in size if machined for this style of seal.
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The Following User Says Thank You to John Milner For This Useful Post: | ||
#5
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Quote:
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#6
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Just had an additional thought. If I have the "tapered or bottle shaped springs" will the metal shields even work?
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#7
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The modern umbrella seals are dimeter specific for fit on .500" or .530" guides, and are tough to install. I ruined a bunch and had to buy more.
The ruin was due to the guides having an edge rather than a pleasant chamfer. The Seal is willing to shear inside, and bunch-up inside, such that the seal wants to pop-up right after the bad install. Also there ought to be a tool, or instructions for how-to-install. Meanwhile you can remove a valvecover and peek inside each spring to see if the seal popped-off and is riding with the valvestem. Had that puffy scene 25 years ago. |
#8
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Pontiac used no seal on the exhaust side and a black rubber seal on the intake - so if you see a seal on the exhaust guide then the guides have been cut for positive seals. In conjunction with the original Pontiac setup an O-ring on the valve stem was used just under the valve stem locks and the metal shield. This complete (archaic) system worked okay at best.
Really unfair to call the positive seals a "Chevy" seal since Viton seals were used on WWII aircraft long before the racing community found out how good they worked. I hate Teflon seals in that they pass more oil down the stem and from my experience they wear rather quickly. Viton is definitely the way to go, and when the guides are cut and Viton seals are installed the O-rings and metal shields need to go away since the Viton seals can be damaged with additional limiting of oil on the stem from the O-rings and shields.
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Mick Batson 1967 original owner Tyro Blue/black top 4-speed HO GTO with all the original parts stored safely away -- 1965 2+2 survivor AC auto -- 1965 Catalina Safari Wagon in progress. |
The Following User Says Thank You to lust4speed For This Useful Post: | ||
#9
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viton since 1957, otherwise great post.
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#10
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" Deceleration " this , IMHO, may end up being rings not seated properly.
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"The Future Belongs to those who are STILL Willing to get their Hands Dirty" .. my Grandfather |
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