Mr. Bee

Mystery Head Bolt?

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My 1939 flathead six has normal bolts holding down the head with the exception of three mystery bolts.  As per the attached images they look like a hex nut just sitting on the head where a regular hex bolt would go.  You can see the thread inside these odd bolts but there doesn't appear to be enough of an engine stud to even grab any of the threads, or maybe barely one thread.

 

There are two at the back, drivers side, nearest the engine starter and one right in the middle.

 

Any ideas what they are and how they are fastened to the head or block?

20180124_170226.jpg

20180124_170319.jpg

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Usually there are only one of these on the rear left side of the head.  Ground strap is attached with a smaller bolt to the inside of the odd bolt.

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Hard to believe there's any meat left between the head of these odd "tapped" bolts with their own shank. The tapped hole must be a bit smaller than the shank thickness below; dunno, as I haven't pulled one of these out yet.  

 

I'm guessing you can't use one of these to clamp a chain onto to lift the engine-tranny.

 

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I've owned my 36 D2 sedan for only a year so I'm far, far from being an expert.  But it looks to me like someone replaced most of the head-mounting studs on your car's engine with bolts.  My 36 has studs for all the fasteners and the nuts are just barely below the top of the stud when tightened.  I think the top of your engine was damaged or someone got a "brilliant idea" about replacing the studs with bolts.

 

Hopefully a forum member with more experience than me will respond and straighten this out.

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I Googled "1939 Dodge engine" and it shows other 1939 Dodge engines with similar head bolts near the middle....two for holding an oil filter bracket....so, I think they are original.

Edited by keiser31 (see edit history)

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Okay...so the last two posts are perplexing.   I just searched "1939 Dodge engine" in Google and I seem to have found some with studs and nuts and some with bolts and or a mix.

 

Does anyone out there have a 1939 Dodge 201.3 engine?  Studs that come out of the block or bolts that go into it?

 

 

 

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Only thing I know for sure is the studs are inserted too far. After tightening the stud should be at least flush with the top of the bolt. That one is only holding by about 2 threads. 

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28 minutes ago, nearchoclatetown said:

Only thing I know for sure is the studs are inserted too far. After tightening the stud should be at least flush with the top of the bolt. That one is only holding by about 2 threads. 

I think those are bolts with threaded heads, aren't they? Like for mounting a bracket atop a head bolt.

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2 hours ago, nearchoclatetown said:

John, you could be right. I was seeing a stud and nut but it could be a bolt that is drilled and threaded. BTW, are you headed to Wisconsin in June?

I wish I could go to Wisconsin in June. I should have been born rich instead of good lookin'....

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Have "they" lost or broken or ? three head bolts and replaced them with studs and nuts? Poor job, the studs are too short. Or maybe the heads broke off the bolts and they have attempted to use the left in place bolt with a thread on the top?

 

Are the head bolts in the coolant inside the head?

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Hey Spinneyhill:  after all the responses so far, I came to the same conclusion you did.

 

I think a couple decades ago someone tried to lift the head.  All the cap bolts came out but three.  I think they snapped the heads off those three with just a couple/few threads still visible.  Once the head was mounted again they just screwed three nuts on what threads were available.

 

 

 

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I would expect those bolts to only have an inch or so of thread on the block end. They would have had to cut a thread on them. Another alternative is if they were actually attempting to torque the bolts assuming a high strength bolt and thus far too much torque. They are probably not much more than about Grade 2.

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Once I get it ready for testing vacuum and compression etc I'll see if I have to pull the heads.  If I do, I'll post what I find about these bolts.

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4 hours ago, Spinneyhill said:

I would expect those bolts to only have an inch or so of thread on the block end. They would have had to cut a thread on them. Another alternative is if they were actually attempting to torque the bolts assuming a high strength bolt and thus far too much torque. They are probably not much more than about Grade 2.

I see here on this 1939 Dodge engine that those type of bolts are holding the brackets on the head.

Picture 8791.jpg

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That is a great reference photo...looks like the are intentionally designed like that.  Weird thing is that my engine has cap bolts that hold down that bracket. 

 

Still a mystery to me.

 

 

 

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It probably means that some twit had the head off and when reinstalling it he/she (I'm trying to be politically correct) had no idea which bolt went where.

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What does the parts book show? All bolts or some studs and nuts?

 

I observe that those nuts are wrong. They studs are too short. The factory would NEVER put a nut on like that with less than half the nut on the thread. There is no strength.

 

Sorry, I think all these photos are red herrings.

 

 

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I have the 1939 original shop manual.  It shows studs with nuts for the 8 cylinder and cap screws for the 6 cylinder.  That's why these odd bolts/nuts are so odd.  What makes it worse is that there are other pics online that show a mix of cap bolts and nuts, or the head-tapped cap bolts that some posters suggested earlier.

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