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Valve guide seals

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El Rocky

Posts: 16

Joined: Sun Jun 10, 2012 8:33 am

Post Thu Jun 28, 2012 1:30 pm

Valve guide seals

Anybody run the valve guide seals on the Knuckleheads, does this run the valve guide dry, and promote galling of valve stem? Or do these work well?
EL Rocky
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fhsmith1

Posts: 213

Joined: Wed Jul 26, 2006 6:10 pm

Location: Georgia

Post Thu Jun 28, 2012 3:25 pm

Re: Valve guide seals

That’s a "boxers or briefs" type question. There are several posts here concerning the pros and cons. I personally have run them about 15000 miles on my 46. I run bronze valve guides machined down to accept Chevy big block valve seals. Heads are Louisiana FHP head castings. It has original type tins. Engine seems happy even though it rarely sees over 70 mph. Only oil problem is the persistent leak.
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fhsmith1

Posts: 213

Joined: Wed Jul 26, 2006 6:10 pm

Location: Georgia

Post Sun Jul 01, 2012 6:25 am

Re: Valve guide seals

If you put seals on the exhaust side you will need to vent the cup like the intake side.
F
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El Rocky

Posts: 16

Joined: Sun Jun 10, 2012 8:33 am

Post Mon Jul 02, 2012 10:50 am

Re: Valve guide seals

10-4, I am glad you mentioned that.
Thanks Rocky
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RUBONE

Posts: 383

Joined: Fri Nov 30, 2007 7:24 pm

Post Mon Jul 02, 2012 11:28 am

Re: Valve guide seals

I've never felt a need to run stem seals in any of my knuckleheads. They work just fine as originally designed.
Robbie
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El Rocky

Posts: 16

Joined: Sun Jun 10, 2012 8:33 am

Post Mon Jul 02, 2012 4:57 pm

Re: Valve guide seals

That is the way I feel about it Robbie, that is how they were designed, should still work, I will use new guides and valves, just to have it as tight as possible.
EL Rocky
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Lee W

Posts: 141

Joined: Sat Sep 23, 2006 8:58 pm

Location: Carver, MN

Post Tue Jul 03, 2012 12:07 pm

Re: Valve guide seals

Fhsmith, could you give me your reasoning for adding a vent to the exhaust spring cup when using seals? Maybe its obvious, but I am drawing a blank.

While I agree that Knucks can "work fine as originally designed" without seals, I would add "if all else is working as originally designed." Over-oiling or under-returning from the heads (caused by a variety of reasons) can be combated to a certain extent by guide seals.
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john k. endrizzi

User avatar

Posts: 726

Joined: Thu Dec 09, 1999 1:01 am

Location: nekoosa,wisconsin,usa

Post Tue Jul 03, 2012 4:00 pm

Re: Valve guide seals

I agree with Lee. Seals do no harm. They are great when vacuum is lost because of ill sealing pushrod tubes, stopped return lines from the tins ect. They help when an aftermarket pump is used and the top end oil is not metered properly. Kyle, please chime in here.
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fhsmith1

Posts: 213

Joined: Wed Jul 26, 2006 6:10 pm

Location: Georgia

Post Wed Jul 04, 2012 2:53 pm

Re: Valve guide seals

Lee W
The vent is about .060" hole found originally in the intake lower tin. It is just under the lip of the upper tin and close the the right side. This is to vent the intake side so oil can be drawn back into the gear-case. The exhaust side was not vented. Since the exhaust port carries no vacuum the venting can be done up the exhaust guide. The intake guide has vacuum so no venting can be done through the intake guide. I've seen intake tins with no vent (mostly aftermarket). This can cause oil buildup inside the tin. There are many threads on the subject.

Seems to me like no matter what you do the damn things still leak. I seem to be able to get mine to stay fairly dry for about 2000 miles and then it slowly becomes the "Exxon Valdeez" again.

Good luck
F
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Lee W

Posts: 141

Joined: Sat Sep 23, 2006 8:58 pm

Location: Carver, MN

Post Wed Jul 18, 2012 12:45 pm

Re: Valve guide seals

Thanks for the answer fhsmith. I had not considered that the exhaust side vented through the guide. I wonder if it needs to though. I have been using seals on Knucks for some time now and had not noticed a problem even though I have not added a vent hole to the exhaust. Of course the symptom of excess oil build up in the tin would be masked by the presence of the seal, so that may explain it.

I wonder if S&S uses a vent on the intake side of the new FHP stuff. I see from the catalog they don't use seals.
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tool$maker

Posts: 1

Joined: Tue Nov 20, 2012 9:57 am

Post Wed Nov 21, 2012 8:43 am

Re: Valve guide seals

Ive always had good luck with a good coating of good old permatex under the tins, no.2 works well no. 1 even better but makes disassembly a little harsh. As far as the seals go I have Lee's 5/16 intake guides in my new knuckle and i didnt use the seals. we'll see.
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fhsmith1

Posts: 213

Joined: Wed Jul 26, 2006 6:10 pm

Location: Georgia

Post Thu Nov 29, 2012 4:19 pm

Re: Valve guide seals

I have another scheme in mind. I have a set of cast iron guides and valves ordered from Kibblewhite. They are backordered but when they come in I plan to have a good machinist cut a groove on the underside of the guide for an O-ring. O-ring would seal the guide to the tin. Also cut the lower spring collar in a bevel manner for another O-ring sandwitched between the guide, tin and spring collar. I already have high temp O-rings. I plan to substitute the soft fiber washers under the tin with a non shrinkable soft metal material. Probably copper. They would just become shims at that point.
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FHP-Eric

Posts: 19

Joined: Mon Sep 27, 2010 12:59 pm

Post Thu Dec 13, 2012 10:07 am

Re: Valve guide seals

We (S&S/FHP) do run vent holes in the upper intake tins, we look at it this way, the Intake port will create a vacuum thru the guide clearance that would counter act the vacuum for oil evacuation, therfore a vent is needed. The exhaust would create a pressure thru the guide clearance aiding in oil evacuation so no vent is needed. One thing i've wondered is if we vented the exhaust side, is it possible that the vent would help stabilize the air in the exhaust tin so that if there were too much pressure from the exhaust (valve guide wear) it wouldn't put pressure on the sealing joints and prevent some leaking or weeping. We (S&S/Flathead Power) are working on a better sealing solution for the knuckles (using high temp oring or seal similar to what fhsmith1 describes), that may include valve giude seals to take the port pressures out of the equasion all together. This soulition would retro fit on any S&S, FHP or Stock heads with no modifications to the heads themselves. I hope to be testing by mid January.
Eric
S&S Cycle, Vintage Lead (formerly Flathead Power)
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fhsmith1

Posts: 213

Joined: Wed Jul 26, 2006 6:10 pm

Location: Georgia

Post Fri Apr 05, 2013 6:45 am

Re: Valve guide seals

Finally got the guides from Kibblewhite. Here are some pics of the machine work. I will use a valve seal on the intake only this time. I plan to also machine the head to accept an o-ring around the rocker shaft where it meets the tin. I will post pics later.
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