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Old January 6th, 2020, 03:01 PM
Uncle Vin Uncle Vin is offline
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Default Cylinder head issue

I have a stock M715. I opened up the valve cover and discovered that one of the cam lobes (the lobe closest to the firewall) was basically wiped out. In addition, there were some rockers that were in need of replacement as well. I replaced the damaged rockers with NOS ones. Since then, I obtained a new NOS cam; NOS cam deck; and a set of NOS rockers. I stumbled on the NOS cam deck for cheap money, so I purchased it. From reading posts on this forum, it is my belief that there is an oiling issue going on with the oil feed to the cylinder head. My suspicion is that there is gunk in the head and/or oil feed line and/or in the oil feed holes in the cam deck which restricts oil flow. The oil feed line to the head looks like it was replaced in the past, as there is no external hose spring present. My issue is that I am concerned that if I install the new cam and deck, those parts will become quickly destroyed. That being said, I am contemplating removing the head and sending it out to a machine shop for work. First, am I on the right track here? and second, even though I think I know the answer (i.e., valve guides, seals, etc), what should I have done to the head at the machine shop?
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Old January 9th, 2020, 10:41 AM
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I'm wondering if the oil supply line was replaced with some inferior tubing and it has collapsed internally. It's most important to be sure that enough oil is flowing to the valve train, even if that means actually looking at it with the engine running before installing the rocker cover.
If you decide to not remove the head, I would replace the oil line with steel tubing, use a good engine assembly lube on everything to keep your new parts from being dry when you start the engine.
If you do remove the head, it will have to be disassembled, tanked to be cleaned, magnafluxed for cracks, planed for flatness, and then I would ask the machine shop if they recommend replacing the guides. If the guides are worn out, then you're looking at new valves and valve seat grinding. This would be an excellent time to have hardened exhaust valve seats installed, but I've never seen any. However, Jeepdan once posted a great link to an engine parts supplier, but I can't remember what the topic of the thread was.
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Old January 9th, 2020, 11:00 AM
Uncle Vin Uncle Vin is offline
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My understanding -- and please someone correct me if I'm wrong -- is that you should NOT deck (flatten) either the block or the head on these specific engines, as doing so introduces slack into the timing chain that cannot be made up by the tensioner and/or permanently damages the timing. The maintenance manual does caution against this: CAUTION
Do not plane cylinder block or cylinder head. This would alter the timing chain centers, piston-to-cylinder-head clearance.


Finally, the maintenance manual also states the following: "Hardened exhaust valve seat inserts were installed in production and will seldom require replacement." Therefore, I assume that the seats can be refaced (three-angle, etc.).

To all: Please feel free to chime in on this thread.

Last edited by Uncle Vin; January 9th, 2020 at 11:07 AM.
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Old January 9th, 2020, 12:10 PM
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Ah-ha! Good find! I wondered, just for a second, if shaving the head would change the timing chain adjustment enough to matter. I supposed that it could be adjusted to make up for the difference. Or thicker gasket. So yeah, don't do that.
I am curious about the hardened valve seats though. Does anyone know more about this? The reason for needing them back then? It must have been necessary, otherwise why bother for a 3 year contract? Can I stop feeling bad when I remember that I forgot to add lead replacer to the fuel tank?
Okay, enough about that. A 3 angle valve job? Personally, I wouldn't spend the money unless I was building at least a street/strip engine. But that is just based on what I can recall from back in the day when I had more engine parts lying around than sense. You may find the perfect combination that makes the 230 the perfect everyday driver. And if you do, I'll be next in line to pull my truck in the shop, pull the head, take it to the machine shop...


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Old January 9th, 2020, 01:04 PM
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As for the hardened valve seats, I know that the Willys F-Head engine also has hardened seats (at least for the exhaust valve seats) as well as exhaust valve rotocaps. Since that engine was used in the M38A1, I can assume that the military mandated the the same type of valve-train for this engine. Although, I admit, I'm unsure.
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Old January 11th, 2020, 08:55 AM
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Hardened valve seats were used because you couldnt guarantee what you would get for gas depending where on Earth you were and what was in it....protect the seat...

There were in the past, dont know about now, .060 thickness shims to put between the block and head if you absolutely had to deck the head and/or block. If there are any around these days, dont know...and that is the only thickness I have seen...fyi...
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Old January 14th, 2020, 10:33 AM
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Brute: What's your opinion on the original question of this post?
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Old January 15th, 2020, 09:12 PM
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What I did because I didnt trust the factory line that leaked like crazy or the one I replaced it with that started leaking in a month....I made a braided stainless line for the connection and never worried about it again...personally, I think it is cheap peace of mind and, because the factory couldnt figure out how to make this an internal passage like everything else uses, an upgrade that really should have come from the factory...
Odds of an internal passage going bad....pretty much zero if you keep clean oil in the thing....odds of the braided stainless line going bad...about the same if you keep clean oil in it...

I wonder if I still have a pic or 2 of that line...
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Old January 15th, 2020, 09:28 PM
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Cant seem to find a pic...might have it on film somewhere but dont have time now to look for it...maybe this weekend if theres time during the snowstorm thats coming...
BTW, reading old posts, I actually blew 3 oil lines in 6 months...thats why I went to the braided...the nos lines just like to leak in my experience.
Also, it is true that only the military engine used the rubber type line. The civvy motor used a solid steel line, like a chunk of brake line with the proper ends, to connect from the block tee to the head...could be fabbed that way to...

As far as the head itself, I would have it checked for straightness and flatness...if it needs to be cut, you are gonna have to find one of the shims they used to put in there to make up the difference...I dont know what else will make it work right.
IF you are going that far, then I would give the seats a 3 angle after the head is tanked and new guides and seals...look at the freeze plugs too...probably a great time to change those...

...of course you might be able to find a head off another motor that wouldnt need all that work and expense...I would try to do that if possible and avoid a shim setup if I could...
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Old January 16th, 2020, 07:34 AM
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When we were putting mine together, we changed out an oil feed hose that was like 2' long coiled up under the exhaust manifold for 3/8 soft copper and brass Swagelok compression fittings. No leaks, no issues so far.
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