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  #1 (permalink)  
Old 03-28-2019, 08:20 AM
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Default threaded valve guide seals

I'm replacing the valve seals on my 427 w/ aluminum heads which appears to have bronze valve guides that are threaded like these:
Manley Valve Guides | Northern Auto Parts

The seals I am replacing are these teflon ones to fit double springs:
COMP Cams: (16) Positive Stop PTFE Valve Seals: For 3/8" Valves & .530" Guides

They have little metal bands around them to stay tight under temp.

I was hoping I could just get them off by unscrewing them, but haven't had much luck there. I'm not reusing them so it's okay if they get damaged prying them off or whatnot.

I'm more concerned about making sure I install the new ones without damaging them so I don't have to wait around for a new set to arrive.

Given my inability to screw the old ones off (at least by hand), I suspect I will have difficulty trying to screw the new ones on. Are these meant to just be pressed on like normal valve seals? My understanding is that the threading is to provide extra grip so they don't slip off. Simply pressing them on seems like it might damage the nylon in the process and make that less effective. Maybe the metal band is meant to be pried open like a snap ring? That also seems like a good way to damage them though.

Finally, I'm wondering if I should apply a bit of oil or assembly lube to aid the process, or if that would defeat the point of the threading in the first place.

Thoughts?

Last edited by Moriarty; 03-28-2019 at 08:53 AM..
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  #2 (permalink)  
Old 03-28-2019, 04:00 PM
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Can you post a better photo of the top of the guides?

Is it truly a thread, or just so fine as to not be useful as a thread, but merely a grip surface for the valve stem seal to adhere to?

Every seal I use has some form of spring band, and that is enough to keep the seal on.

Don't like teflon seals, I prefer Viton.

Gary
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Old 03-28-2019, 07:27 PM
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Quote:
Originally Posted by Gaz64 View Post
Can you post a better photo of the top of the guides?


I found this video on youtube after posting, which looks like the same type and he just pushes them on. Of course, there's no end of examples of the wrong way to do things online. https://www.youtube.com/watch?v=qY6Gx-7ZJ2I

Quote:
Don't like teflon seals, I prefer Viton.
Yeah - I had the original part numbers from the engine builder, so I just ordered the same ones to replace with to make sure everything fit nice.
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Old 03-28-2019, 07:58 PM
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Quote:
Originally Posted by Moriarty View Post
I'm replacing the valve seals on my 427 w/ aluminum heads which appears to have bronze valve guides that are threaded like these:
Manley Valve Guides | Northern Auto Parts

The seals I am replacing are these teflon ones to fit double springs:
COMP Cams: (16) Positive Stop PTFE Valve Seals: For 3/8" Valves & .530" Guides

They have little metal bands around them to stay tight under temp.

I was hoping I could just get them off by unscrewing them, but haven't had much luck there. I'm not reusing them so it's okay if they get damaged prying them off or whatnot.

I'm more concerned about making sure I install the new ones without damaging them so I don't have to wait around for a new set to arrive.

Given my inability to screw the old ones off (at least by hand), I suspect I will have difficulty trying to screw the new ones on. Are these meant to just be pressed on like normal valve seals? My understanding is that the threading is to provide extra grip so they don't slip off. Simply pressing them on seems like it might damage the nylon in the process and make that less effective. Maybe the metal band is meant to be pried open like a snap ring? That also seems like a good way to damage them though.

Finally, I'm wondering if I should apply a bit of oil or assembly lube to aid the process, or if that would defeat the point of the threading in the first place.

Thoughts?
The threaded guides say they're 0.502" O.D., while the teflon seals say they're for 0.530" O.D. guides. Am I missing something?
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  #5 (permalink)  
Old 03-28-2019, 08:37 PM
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Quote:
Originally Posted by cycleguy55 View Post
The threaded guides say they're 0.502" O.D., while the teflon seals say they're for 0.530" O.D. guides. Am I missing something?
I only posted the guide link above as an example of the type. They are not the actual guides in the heads.
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Old 03-29-2019, 02:11 AM
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https://www.ebay.com/itm/16-Metal-Bo...-/252717312707

I would think any "press on" valve stem seal would be ok.

You use a thin plastic guide like a condom over the stem so the seal doesn't get damaged by the collet grooves, then once the seal is on far enough, the plastic guide can be removed.

The seal is then driven on to the guide with an appropriate seal drift.

Whether you use .502 or .500 , your choice.

Is your stem size 11/32?

Gary

Last edited by Gaz64; 03-29-2019 at 02:14 AM..
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Old 03-29-2019, 07:19 AM
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What appear as threads on the guides, are not. They aren't threaded spirals, just uniform rings to help with seal retention. Grab the old seal around the wide body area with pliers, don't get Neanderthal, wiggle and pull. You may be surprised at how easily they come off. They won't deform if you use minimal plier pressure.

Then follow Gaz64's assembly advice. I like to pre-oil everything before pushing the new seal on.

Last edited by HTM101; 03-29-2019 at 07:30 AM..
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