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56D500boy

Posted 2024-03-19 10:46 AM (#634285)
Subject: A potentially more feasible reason for an oil smoke puff when starting a Gen 1 hemi

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.
Previously, I said:

"Sometimes when I start my 56 Dodge D500 315 hemi, I get a bit of a puff of smoke. I put that down to leaking valve stems seals (? - at least that is my thought). *IF* I was to change the seals, I am thinking that I could potentially do so by sliding the rocker over, against the spring while I proceeded to compress the spring(s), remove the keeper and the top hat, then spring(s) and then the worn valve stem seal (I would start with that before removing the head(s) to do the guides, etc."

I was told basically, "Don't worry be happy" and never did anything. It happened randomly, not predictively, and didn't last long. So I let it slide.

Recently, I decided to replace my AR45S spark plugs with AR43S plugs. In doing so, I encountered spark plug wells that were very wet with oil. The oil was NOT in the metal spark plug tube but it was in the cast/machined recess in the head.

In order get a good seal between the metal spark plug tube and the head and, thereby, minimize potential oil leakage onto the spark plug threads, I soaked up the oil with a paper towel taped to a long 3/8" rachet extension (only thing I had that was long and stiff enough). Took a few goes/paper towels to soak up the oil clean up the area where the end of the spark plug tube lands on the head, just above the double rocker/hemi combustion chamber.

That done, I inserted the AR43S plugs, one by one, into their respective tubes a re-inserted them into the head. I tightened to the German spec "Gudunttight" which hope is about the same as the official 30 to 32 lb - ft.

Point of the story: If the metal spark plug tube is not tight to the head or there is some debris under the end of the tube (or both), there is a greater than zero chance that you a) will get a puff of oil smoke on start up and/or end up with oil-carboned plugs like the ones below.

Some photos and diagrams to illustrate my point:

Edited by 56D500boy 2024-03-19 10:55 AM

(CrustyAR45S.jpg)

(DoubleRockV8CutAwayShowingSparkPlugTubeNo80.jpg)

(DoubleRockV8CutAwayShowingSparkPlugTubeNo80_Detail.jpg)

(53-57DodgeHemiSparkPlugTube_PN1328368.jpg)

(51HemiValveTrainCutAway.jpg)

(DaveFs565D500EngineValveTrain_RightBank1-3-5-7_SparkPlugWells.jpg)

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CrustyAR45S.jpg (85KB - 21 downloads)
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DoubleRockV8CutAwayShowingSparkPlugTubeNo80.jpg (179KB - 25 downloads)
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DoubleRockV8CutAwayShowingSparkPlugTubeNo80_Detail.jpg (180KB - 24 downloads)
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53-57DodgeHemiSparkPlugTube_PN1328368.jpg (149KB - 29 downloads)
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51HemiValveTrainCutAway.jpg (68KB - 29 downloads)
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DaveFs565D500EngineValveTrain_RightBank1-3-5-7_SparkPlugWells.jpg (139KB - 29 downloads)

57chizler

Posted 2024-03-19 2:00 PM (#634291 - in reply to #634285)
Subject: RE: A potentially more feasible reason for an oil smoke puff when starting a Gen 1 hemi

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This has been an issue since the inception of the Hemi and it only becomes a "problem" when the spark plug is loosened and breaks the seal of the bottom of the tube to the "wells" in the head. Once installed, the tube acts as a gasket to prevent oil from fouling the plug.

56D500boy

Posted 2024-03-19 4:27 PM (#634296 - in reply to #634291)
Subject: RE: A potentially more feasible reason for an oil smoke puff when starting a Gen 1 hemi

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.
I guess this has been enough of a problem that Hot (Hemi) Heads came up with a solution.

"These aluminum seals press fit into the cylinder heads and provide a snug, o-ring contact on the spark plug tubes. Facilitates accurate plug reading and prevents oil seepage into combustion chambers. To install these seals, the spark plug hole in the head must be machined to 1.500-inch diameter and .250-inch deep, centered with spark plug hole. Purple anodized finish and includes o-rings. Set of eight."

https://hothemiheads.com/dodge/cylinder_heads/spark_plug_seals_alumi...

Regardless of how annoying this might be, I am not removing the heads for machining to cure it.

57chizler

Posted 2024-03-20 12:48 PM (#634306 - in reply to #634296)
Subject: RE: A potentially more feasible reason for an oil smoke puff when starting a Gen 1 hemi

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Those seals are mainly meant to facilitate spark plug reading. They only work marginally on perfectly round tubes.

dels56

Posted 2024-03-21 12:13 AM (#634323 - in reply to #634285)
Subject: Re: A potentially more feasible reason for an oil smoke puff when starting a Gen 1 hemi

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Are you fellows sure that oil can find it’s way between the tightened down spark plug and aluminum tube that provides the seal? Then the oil would have to find it’s way through a 3/4” reach 14mm thread, that would be a very tiny capillary tube for any amount of oil to drain through and get into the combustion chamber while the engine is stopped. Food for thought.
Del

Powerflite

Posted 2024-03-21 1:39 AM (#634324 - in reply to #634285)
Subject: Re: A potentially more feasible reason for an oil smoke puff when starting a Gen 1 hemi

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If you don't remove the washers on the spark plugs, then you will get a lousy seal and screw up the end of the tube. Trying to re-use a tube that has been screwed up will also cause a leak. That's the usual cause.

22mafeja

Posted 2024-03-21 3:00 AM (#634327 - in reply to #634285)
Subject: RE: A potentially more feasible reason for an oil smoke puff when starting a Gen 1 hemi

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Would it be possible to planish the sealing surfaces of the tube in a lathe? It would require a long tool holder to reach to the inside but it might be possible.

56D500boy

Posted 2024-03-21 11:47 AM (#634330 - in reply to #634323)
Subject: Re: A potentially more feasible reason for an oil smoke puff when starting a Gen 1 hemi

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dels56 - 2024-03-20 9:13 PM
Are you fellows sure that oil can find it’s way between the tightened down spark plug and aluminum tube that provides the seal? Then the oil would have to find it’s way through a 3/4” reach 14mm thread, that would be a very tiny capillary tube for any amount of oil to drain through and get into the combustion chamber while the engine is stopped. Food for thought.

Thanks for the thought(s) Del and Ralf and . I only through that out there as a possibility and maybe a reminder to those with the older hemis.

My main take-aways are:

1. Don't use the spark plug crush washers, they pull the tip of the spark plug back into the head (which might result in crud NOT burning off the tip and thereby accumulating)
2. When the spark plug and aluminum tube are removed, there will some oil down that well. It needs to be soaked up ASAP and the tube/spark plug landing surface cleaned as much as possible.
(Somebody must have made a tool to lightly buff that surface (??))
3. Clean the lower end of the aluminum tube so there is no crud to create a capillary tube before re-installing with the spark plug.
4. After gapping the plug, don't risk closing up the gap by dropping the plug down the tube (electrode might hit the bottom of the tube.) Load the plug into a spark plug socket and slide the tube
over the plug. Make sure that the entirety of the threads (3/8" in my Dodge's case) are sticking out of the tube.
5. Install the plug and tube as a unit and torque to 30 to 32 lb-ft.
6. Keep fingers crossed that there will be no leakage.

Edited by 56D500boy 2024-03-21 1:07 PM

57chizler

Posted 2024-03-21 1:10 PM (#634334 - in reply to #634323)
Subject: Re: A potentially more feasible reason for an oil smoke puff when starting a Gen 1 hemi

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dels56 - 2024-03-20 9:13 PM

Are you fellows sure that oil can find it’s way between the tightened down spark plug and aluminum tube that provides the seal? Then the oil would have to find it’s way through a 3/4” reach 14mm thread, that would be a very tiny capillary tube for any amount of oil to drain through and get into the combustion chamber while the engine is stopped. Food for thought.
Del

In order for oil to reach the threads and seep into the cylinder, it would have to pass under the tube which acts as a gasket. Possible? Yes. Probable? No. Even a tube that's distorted at the mating surface will seal pretty well with the plug tightened against it.

And, the 3/4" of tightened threads themselves are a pretty good seal..I suspect there would be no capillary action even without the tube as a gasket.

dels56

Posted 2024-03-21 1:47 PM (#634336 - in reply to #634285)
Subject: Re: A potentially more feasible reason for an oil smoke puff when starting a Gen 1 hemi

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So then Dave’s “puff of smoke” is more likely to be from oil running down the valve stem, either caused by a worn (old) valve stem seal or the fit between the valve stem and guide? I would not worry about a Puff as the cost of a top up of oil once in a while is cheaper than ripping the top end apart.
Del

57chizler

Posted 2024-03-22 12:23 PM (#634365 - in reply to #634336)
Subject: Re: A potentially more feasible reason for an oil smoke puff when starting a Gen 1 hemi

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57chizler

Posted 2024-03-22 12:24 PM (#634366 - in reply to #634336)
Subject: Re: A potentially more feasible reason for an oil smoke puff when starting a Gen 1 hemi

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Affect of oil on intake valve.

57chizler

Posted 2024-03-22 12:29 PM (#634367 - in reply to #634336)
Subject: Re: A potentially more feasible reason for an oil smoke puff when starting a Gen 1 hemi

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Affect of oil on intake valve.

(IV Deposit.PNG)

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IV Deposit.PNG (118KB - 22 downloads)

56D500boy

Posted 2024-03-22 1:17 PM (#634370 - in reply to #634336)
Subject: Re: A potentially more feasible reason for an oil smoke puff when starting a Gen 1 hemi

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dels56 - 2024-03-21 10:47 AM
So then Dave’s “puff of smoke” is more likely to be from oil running down the valve stem, either caused by a worn (old) valve stem seal or the fit between the valve stem and guide? I would not worry about a Puff as the cost of a top up of oil once in a while is cheaper than ripping the top end apart.

I agree. While annoying and a bit embarassing, those "puffs" of smoke on the odd/random cold starts don't happen that often. No way I am removing the heads to fix a minor guide issue.

wizard

Posted 2024-03-22 1:48 PM (#634371 - in reply to #634285)
Subject: Re: A potentially more feasible reason for an oil smoke puff when starting a Gen 1 hemi

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Two ways to change the valve seals without removing the heads;

1 Remove the insulator and everything inside on an old spark plug. Weld a piece of pipe, with threads for a pneumatic fitting. Turn the engine to tdc on one cylinder. Install the modified sparkplug. Block the engine so it wont turn. Apply compressed air (be sure that the compressor is good and ok.
With a wooden mallet, hit the valve springs. Now it is possible to compress the spring and remove the valve locks.

2 Get a good quality of rope in diameter sufficient for to go through the spark plug hole. Turn one engine until 3/4 stroke before tdc. Insert as much of rope that you can. turn the engine until it's blocked. Make sure the engine cannot turn. With a wooden mallet, hit the valve springs. Now it is possible to compress the spring and remove the valve locks.

In both ways, one must fabricate a valve spring compression tool that can be bolted on the heads

Note #1 - theres a high risk if the compressor fails or the engine turns, or if the blowby is excessive, then you might see the valve falling down in the cylinder.

dels56

Posted 2024-03-23 1:34 AM (#634383 - in reply to #634285)
Subject: Re: A potentially more feasible reason for an oil smoke puff when starting a Gen 1 hemi

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The reason Wizard suggests “with a wooden mallet, hit the valve spring” is, the valve locks will be stuck to the retainer and valve stem and giving the valve spring retainer a wack with a mallet will loosen them up for you. Then you need a “tool” of some sort to press down on the retainer to expose the locks so you can pick them off the valve stem. Once you have done this you then release your down pressure on the tool which allows you the remove the retainer and valve spring. Now you can remove and replace the valve stem seal. Reverse the procedure to replace the spring, etc. I can look in my box of old tools once I am back in my shop to see if I still have the “tool” for you to use.

Del

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