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Dante Garofani · 03-26-2002, 02:55 AM

I read an old HO Racing book that stated the small O-ring located on the second groove of the intake valve and held in-place by the stock retainer is critical to keep oil from traveling down the valve guides and entering the combustion chamber. The article states that P.C. seals on the guide are not enough to stop excessive oil though the valve guides. My question is, since all the popular replacement retainers (CompCams, Crane etc...) are too short to capture the O-Ring, how critical is it maintain? Is there an aftermarket retainer that is long enough? Thanks for any responses.

Dante Garofani · 03-26-2002, 02:55 AM

I read an old HO Racing book that stated the small O-ring located on the second groove of the intake valve and held in-place by the stock retainer is critical to keep oil from traveling down the valve guides and entering the combustion chamber. The article states that P.C. seals on the guide are not enough to stop excessive oil though the valve guides. My question is, since all the popular replacement retainers (CompCams, Crane etc...) are too short to capture the O-Ring, how critical is it maintain? Is there an aftermarket retainer that is long enough? Thanks for any responses.

Will · 03-26-2002, 03:14 AM

Dante, despite what that book says, many people, including myself, are doing just fine with positive seals on the intakes and no O-ring on the valve. You pretty much have to go this route when running aftermarket valves as most (all?) don't have the lower groove for the O-ring anyway, and thinner retainers provide more clearance for higher lifts. It helps to run bronze guides and clearances that aren't too loose.

[ March 26, 2002: Message edited by: Will ]</p>

Half-Inch Stud · 03-26-2002, 09:50 AM

LIKE WILL SAID.

My heads seem to go together with the Teflon seals on the Intake valveguides. Seems the O-ring doesn't get into the Valve retainer due to lack of need.

HOWEVER:
Seems my Intake valves get the black crust accumulation. I'm darn tired of that. So, I was thinking of an idea to install an oil deflector on the Intake valve stem at just the right position in the valve bowl.

Oil would continue to seep out of the valveguide, down the intake valvestem, but would hit the deflector and accumulate. Then the Intake stream would blow the oil off and into the chamber.

I was thinking of using the O-rings and some JB-Weld to keep the rings in place (from riding up and jambing the valveguide and hanging the valve).
I was thinking that some outfit like BOP could make thin metal doilies that could get spot welded to the valvestem. Such a flat sheet doilie part could be designed to affect flow in a helpful manner.

I think this would keep the intake valve backside cleaner, while keeping the intake guide lubricated.

Anybody as stoned as me?
Keep your stick on the ice.

H.I.Stud

Dante Garofani · 03-27-2002, 03:59 AM

The carbon residue is also on the backside of my intake valves. These heads were assembled with bronze guides, Ferrea valves, Teflon seals and CompCams retainers. I was surprised to see the crud on the valves as the heads only have 1k on them since rebuild. I was wondering if the missing O-ring was the culprit or just normal accumulation. I'm going to clean the crud off the valves and reinstall the stock retainers (Ferrea valves do indeed have the lower groove) with the O-ring and check it after another 1k. That ought to satisfy my curiosity. Thanks for the helpful replies.

Dante Garofani · 03-27-2002, 04:05 AM

[ March 27, 2002: Message edited by: Dante Garofani ]</p>

Will · 03-27-2002, 06:09 AM

Do you have the part number for those valves? My Ferreas didn't have the O-ring...

Dante Garofani · 03-27-2002, 07:56 AM

Doh!! Mellings, Mellings, I'll promptly have this tattooed to MY head! Sorry Will, the wifey's car has Melling valves with the provision for the O-ring. You are absolutely correct that Fearra valves do not have the second groove. Sorry for the mistake.

Will · 03-28-2002, 04:23 AM

S'allright Dante, we don't shoot people around here for mixing up their valve brands.

Now putting a Chevy between your fenders, that's a real crime! [img]/infopop/emoticons/icon_biggrin.gif[/img]

Not having a Melling catalog handy, I wonder - were those stock replacement type valves or stainless? I'd like to know of a stainless valve option that has the O-ring grooves if it exists.

Half-Inch, some theories hold that at least part of that black crud on the backs of the intake valves is congealed/coked fuel, and that some of the oil that comprises it makes it's way in via the PCV valve. Do you see any merit in those guesses?

In any case, I have a hard time believing a positive seal at the top of the valve guide, and a nice tightly clearanced bronze guide at that, is any less effective than an O-ring around the valvestem a little over 1/2" above the guide boss. Since most aftermarket springs will eventually do a number on the metal spring shields, most people discard them also, and without them, what good does that O-ring do?

Half-Inch Stud · 03-28-2002, 06:04 PM

Will,

I've tried to use those stock metal spring shield too, but they just don't fit the 995 springs. The O-ring has been left out of my combos.

To reiterate:
I suggest putting a metal diverter on the valve stem, in the valvebowl region...to keep oil films from reaching the valvehead.

Further suggest that those little O-rings could be used as the diverter if they were staked to the valve stem with epoxy or within a lathed groove in the valvestem. Would sure dislike a hung valve from an O-ring jamming into the valveguide....on a whim of an idea too.

H.I. Stud..........Mark

Bruce Meyer · 03-28-2002, 07:29 PM

Will- I think your right about the black crud on the intake valve is burnt gas. The exhaust valves never seem to have it. Also you might find this interesting. A buddy of mine with a 360 mopar had carb problem where the fuel would boil out of his carb after he shut it off. When he pulled his carb that same black crud was piled up on the bottom of his plenum of his intake manifold. It seems the fuel would puddle there and get cooked by the heat riser passage.

Dante Garofani · 03-29-2002, 04:13 AM

Will, The heads were put together by a local engine builder and I remember (after the fact) the Melling's box for the valves but not the part numbers. The rebuild was stock with the addition of CompCam springs + hardware, hardened seats, and Teflon seals.

You guys make a good case for the PCV blow-by and normal fuel residue. Again, The old H.O. book was adamant about the little O-rings and it got me wondering if others, such as yourselves, had any experience with oil consumption through the stem guides as well as the black crud on the back side of the intake valves. I suspect the lack of crud on the exhaust valves has to do with the positive pressure of the exhaust system.

I'm going put the O-rings on and check the heads with a boroscope (nice to have friends in aviation) in another 1k and report my findings.

BTW, the PCV explanation is a good one - anyone going without and just using the breathers to vent the crankcase? Thanks

Half-Inch Stud · 03-29-2002, 12:53 PM

Instead of using the O-Rings, I used Silicone sealer within the Retainer assembly...in the late 80's. Not sure if I liked it because it makes for a tough future disassembly&cleanup.

Besides, I recall the little O-rings make it tough to install the keepers without knicking them O-rings.

H.I.

Half-Inch Stud · 03-29-2002, 01:03 PM

I can neither confirm nor deny that my PCV system is not there, and there are two Mickey Mouse breathers on top the valvecovers, and there are two edelbrok cast vents on the sides of the valvecovers.

I can confirm that I have Total-Seal rings.
I can confirm that I have a bone-dry engine compartment, devoid of blowby. since the used motor was installed in 1996.

H.I. Stud

Skip Fix · 03-29-2002, 07:59 PM

SI makes stainless valves that you can get with dual grooves. Some of the hi perf Sealed Power/FM valves also are stanless and have 2 grooves.

Bartman · 03-30-2002, 12:15 AM

Coked fuel is most likely the culprit. Todays premium fuel leave very hard deposits when evaporated on hot components like intake valve. Port fuel injected cars are the worst though since the fuel is sprayed right on the intake valve. Low velocities of street driving cause most of the build up.
If you deposits are soft then they most likely are from oil leaking down the guides.
Also be weary of using valve with the o-ring groove with high spring pressure(big solid or roller cam). This is a major weak point in a valve stem.It was a major point of engine failure in stocker racing up until they allowed aftermarket valves.

JC455 · 03-30-2002, 01:27 AM

I've got a set of stainless valves for some 6X's. The manufacturer is unknown, but the intakes have HP2639 on them. They are a single groove valve. The exhaust has part number P2638HP-C on them and they have 2 grooves. I wonder why they would have the dual grooves, as I thought the problem was on the intakes??
What clearance do you guys run, and do you run stainless valves w/ bronze liners for the lubrication factor?
I've eluded to this situation on several occasions, but nobody has really spoke up. I'm glad to see this is being addressed.

[img]/infopop/emoticons/icon_biggrin.gif[/img]

JC455 · 03-30-2002, 01:32 AM

Another question- What brand of gas do you run? I wonder if something like Chevron's Techron or Texaco's System 3 makes a difference on the crud accumulation??
Hmmm...

Dante Garofani · 03-30-2002, 02:53 AM

I don't know about the Texaco fuel but Chevron premium is the only fuel I put into my cars...hmm another variable to consider.

Bob Eiler · 03-30-2002, 04:01 AM

The black carbon deposits are caused by excess oil, heat, blowby or poor pcv system. I've been rebuilding heads since the mid seventies and this has always been a problem with Pontiacs. Bronze guides with .001 clearance helps, all teflon seals don't. I have been using 5.0 Ford oil shields that slide to the top of the seal. It works. I have disassembled Ford heads with 150,000 miles on them with very little carbon deposits on the backside of the intake valve. The shields are fibre, .790 in. in dia.(can be trimmed), .030 thick and weight just .3 gr.

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