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Discussion Starter · #1 ·
I ask a performance shop about using the Viton type seals and they said they wouldn't use them on a dual spring application, they would use the PC type. My understanding is that the PC Types are too effective in stopping oil from lubricating the guides.
Are any of you guys running the PC Type seals having any issues with guide wear??
They also said that BBC Heads are nortorious for guide wear. Is this true??
 

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I don't know about notorious but my 454 Dart Iron Eagles came with pc seals 6 out of 8 ex. guides are destroyed. I bought the heads several years ago during restoration (just over 5 years) ran the heads for 1 year Dart rep states they no longer use the pc seals. Things that make you go hummmmm. Check with Mike at Wolfplace. I'll be using the viton seals with dual springs.
 

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G,
I have not really seen any problems that I can positively attribute to the pc seals. Some guys will even tell you that let more oil down the guide than the viton ones ! I personally agree with them, I think the viton is a better seal. Depends on who you talk to. We used the PC seals for years before the better viton type became available and really never had any guide problems. All of the OEMs use the viton type seals now days and they want very little oil getting down the valve stem because of emissions concerns. I personally think that guide finish and rocker geometry are a whole lot more important than the type of seal you use. We almost always use a spiral grooved cast iron guide in iron heads and just do not have guide wear problems.

Another thing that seriously affects guide wear is valve seat runout. I hate to say it, but I bet that half the machine shops out there dont even own a runout gauge. You can do a pretty good job checking it by using a real fine lapping compound, but the gauge really tells you if you are getting it right. If there is too much runout, every time the valve closes it tries to move to one side. This will kill guides real fast.

That being said .... every shop has some different ways of doing things that have worked well for them for many years. I would trust them, they will have to stand behind it if you have a problem. If you "make" them use the viton seals and you have a problem, you might get the old "I told you so" :(

Just my opinion,
 

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Discussion Starter · #4 ·
Thanks Bill, i really don't want what happened to Aukai's heads to happen to mine.
One more question, when bigger valves are installed are the new seats cut using the valve guides to center the seats?
 

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Yes,
All of the tooling lines up on the guides, that is why they have to be in good shape. With a sloppy guide, you will get a sloppy valve job.
 

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I have been using the metal encapsulated Viton seal for about 20 years now & have not used a PC seal for about the same amount of time.
In my experience the PC seals will dry up the guide when they are new & will leak when they get some miles on them.
An old trick with the PC seals used by some of the head gurus was to either remove the top ring or to run a reamer through them to keep from eating up the guides.

Almost all the aftermarket head manufacturers have gone to the Viton seal because it does a better job of METERING oil without excessive usage.

Almost every OEM from GM to Honda, Toyota etc uses them.
I highly recommend them.

But,,, I do have to agree with Bill on one point here, if the shop is going to stand behind the heads at all use what he recommends
You can always bitch later :D
 
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