H D truck engine sodium valves.

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reddog565

Senior Member
Hi guys! You guys always have great repys!
I have this 272 h.d. truck engine. It's been totally rebuilt with reconditioned heads. I'm having an oil burning issue, meaning it's going past the exhaust guides. There are no valve seals on the exhaust valves on this motor.anyone that's familiar with this particular engine knows the exhaust valves are sodium-filled and they are larger diameter stem. Does anyone know of what kind of umbrella valve stem seals I could use on these exhaust valves? I really don't want to take these heads off again and get them machine, it's too much of a job...
Thanks!
 
Good reply! I'm going to have to pull the valve covers and take a look at that..that would probably be a first for these engines, you know they have lack of oil up top.
Thanks...
 
The 272 in my car was "rebuilt" before I bought the car. It was using oil pretty rapidly and the right side exhaust was oily. I pulled the rocker covers and found a lot of oil coming from around the rockers on the right side. Turns out the shaft and rockers were worn and galled allowing too much oil to escape around them. New shaft and rockers brought the oil burning under control. I know you said that the rockers can't get too much oil with "tongue in cheek" but you can get enough up there to flood the valves.
 
reddog565 said:
I have this 272 h.d. truck engine. It's been totally rebuilt with reconditioned heads. I'm having an oil burning issue, meaning it's going past the exhaust guides. There are no valve seals on the exhaust valves on this motor.anyone that's familiar with this particular engine knows the exhaust valves are sodium-filled and they are larger diameter stem. Does anyone know of what kind of umbrella valve stem seals I could use on these exhaust valves? I really don't want to take these heads off again and get them machine, it's too much of a job...
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Wondering (as I usually do) ... :confused:

Is this engine in a pickup or heavier truck? If pickup, how did you decide to use?

The 272 HD is a torque engine, meant for low RPM usage and low gearing. It is not rated for passenger car use.

As for the seals, it was assembled with none on the EXH side. Low RPM usage would not really require them if the stems/guides are tight.

TED EATON is going to be the best source if info by far (IMO). The FYB and LYB HD engines are a different animal.

BTW - The INT VLV is 5.02" L and the stem dia. is .3402" STD size.

The EXH VLV (1956 272HD) is 4.92" L and the stem dia. is.4345" STD size. The reduced stem length is to allow for the 6550 lash caps.

Did the machine shop mention there being no seals when the heads came in?

Exactly how much oil does it consume? Does it show on spark plug readings?

My guess ... :rolleyes: ... is as the valves absorb engine heat and the sodium liquefies, the resultant stem heat would ruin the seals quite quickly.

OH! This era of sodium filled valve stems are known for the valve head separating from the stem in fairly high RPM usage.



Please keep the board informed on this thread as to what you find.
 
these engines work fine in a car.i put one in my 56 awile back.just changed the base and in it went.cite crank and rods 471 heads 292 .040 over.didnt smoke and gave about 1000 to quart.good on gas.i had always wondered what they would be like in a car and this was a low milage rebulit.real nice engine.had about the same power as the one i pulled.
 
What a great reply! This is a HD truck engine. And I know the exhaust valves don't come from the factory with Seals. I believe there is one model that does. I probably should have took it to a machine shop with a better understanding of these old heads. I don't know if they were familiar with the sodium valves,? anyways you gave me the answer I was looking for and I needed to know the valve stem diameter of the exhaust valves. When you get a rebuild kit they give you 16 umbrella seals assuming that you don't have oversized valve stems. Once again you guys on The Barn, always have great replies!
 
Forgot to answer a couple of your questions?
The plugs do not appear to be oil fouled. But, I did remove the headers and I could visibly see oil residue on the exhaust valves.. and I do have to put some makeup on oil in it. But, it's the blue smoke upon startup that is very discerning to me. Then you brought up another good point. With the sodium heating up in the exhaust valves you're absolutely right it could destroy the seals quite quickly. So, what am I supposed to do with this?
 
The exhaust valve always has positive pressure on it when the valves open. The intake is subjected to low pressure so that's the one you generally have to worry about drawing oil in through the guides. Modern high temp elastomers like fluorosilicone can take a lot of heat but I don't know that you will need anything on the exhausts. Exhaust valves can get carboned up and stick but it depends on the clearance in the guide. The Lycoming aircraft engines use near 1/2" diameter sodium filled exhaust valves and they have to be checked every 300-hours on the helicopters. The check is for looseness but more often than not, they get carboned up and have to be reamed with a .501" reamer to get the stuff cleared out. You likely won't have to worry about this on a Y-block as long as your rockers are holding their mud like they should.

The weld process on sodium filled valves is generally pretty good but it might not be as strong on smaller stem types. Most valves have the heads welded on and have since Charles E. Thompson developed the process over 100 years ago.
 
Maybe I’m missing something but I have always installed seals on exhaust valves and really don’t know why. As rotorwrench states there is always positive pressure on the exhaust valve thus oil won’t be sucked down the stem into the cylinder like the intake valve. So can someone enlighten me why there are seals on exhaust valves.
 
I don't have the specs at hand, but I would imagine that these sodium filled valves need extra guide clearance to handle all the extra heat carried up the stems under full load. The idea was to transfer heat from the valve head up the stem and into the guide, then into the water jacket. Remember, these HD 272 and 292 engines were built to run under full throttle full load conditions all day (so operating guide clearances would close up with all that heat). If you're just putt-putting around with light throttle, it may be normal to use some oil.
 
reddog565 said:
When you get a rebuild kit they give you 16 umbrella seals assuming that you don't have oversized valve stems. Once again you guys on The Barn, always have great replies!
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The manufacturer is just cutting down on inventory. Like a carb kit, will work on many different applications. FORD did it also.

reddog565 said:
Forgot to answer a couple of your questions?

The plugs do not appear to be oil fouled. But, I did remove the headers and I could visibly see oil residue on the exhaust valves.. and I do have to put some makeup on oil in it. But, it's the blue smoke upon startup that is very discerning to me. Then you brought up another good point. With the sodium heating up in the exhaust valves you're absolutely right it could destroy the seals quite quickly. So, what am I supposed to do with this?
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As previously suggested, you need to verify oil delivery to the heads. If the supply system was 'jacked up', it may be overwhelming the valve guides.

FORD used an 'oil deflector' up to about 1955 on the FYB AND LYB HD engines whereas any splash-over would be directed around the valve guides. Also check rocker arm to shaft clearances. Might be excessive clearance there allowing a greater oil supply to hit the guides.

Coolant temp good? Correct spark plug heat range?

If TED EATON can't answer it, you will just have to go with common sense. Maybe consider acquiring a set of pass car heads?

Again, what year engine and what are you using it in?
 

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Coolant temperature is about 200. A little bit warmer than I would like. I'm running a 180 thermostat, with it electric fan. It does have oil deflectors on it. And I'm running the recommended autolite spark plugs. A lot of great thoughts you guys..
 
If there is always pressure being present in the exhaust port how is oil consumption a factor from the exhaust valve and guide? I understand the intake as you have a vacuum that can pull oil into the cylinder due to a bad seal and or guide. I’m not arguing with anyone’s opinion just trying to find out why exhaust valves have seals.
 
wellcraft17 said:
If there is always pressure being present in the exhaust port how is oil consumption a factor from the exhaust valve and guide? I understand the intake as you have a vacuum that can pull oil into the cylinder due to a bad seal and or guide. I’m not arguing with anyone’s opinion just trying to find out why exhaust valves have seals.
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If you notice, everyone has their own theory and opinion. The correct answer can be found in a theory text. I am too old and tired to get into food fights any longer. I try to answer a question to the best of my knowledge and let it go from there.

If the seal was not necessary, FORD surely would not use it.
 
I appreciate everyone's opinions! And everyone taking the time to answer! And yes we're all getting too old! That's why I don't want to pull these heads off again it'll be the fourth time!
And remember most of all, do not take the wife to Subway!!!!! That's a guaranteed war..
 
reddog565 said:
I appreciate everyone's opinions! And everyone taking the time to answer! And yes we're all getting too old! That's why I don't want to pull these heads off again it'll be the fourth time!
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You never gave the year of the engine or type of vehicle it is in...

And remember most of all, do not take the wife to Subway!!!!! That's a guaranteed war..
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You haven't heard the all of it.

Late one evening, the wife mentioned maybe my getting some pills to help with my sexual performance problem ...

The next day after work, I came in and handed her a bottle of diet pills ...

And then the fight started... :p

She treats me like a red-headed stepchild ...
 
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