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Exhaust manifold removal
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imfinlay
Posted 2019-07-05 3:55 PM (#584466)
Subject: Exhaust manifold removal


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OK, so I got all the studs out of the manifold. Well, some were the nuts, some were the studs too. Except for the one that sheared off - of course, one that goes into the water jacket. Until I get the manifold off I can't see if there's enough stud left to grab onto, but now I can't move the nuts to the downpipe.

If I shear those off, is any harm done? It seems they're on a stud through the manifold, so can be easily replaced, but the parts manual only shows one nut, which only makes sense if the manifold is threaded. Which the replacement isn't...

And.. is it even possible to take the manifold off if there are studs left? I can't see how there's clearance. Reassure me I don't have to take the head off... If I do, I'll take both off and do an unleaded conversion, but I really didn't want to go that far at this point.

301 V8 in a '57 Plymouth.



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Powerflite
Posted 2019-07-05 6:38 PM (#584472 - in reply to #584466)
Subject: Re: Exhaust manifold removal



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Pretty hard to remove a sheared off stud in a head without taking the head off. You may be able to get the exhaust to seal without that stud, but most likely it will result in a small exhaust leak. Removing the broken studs isn't usually too difficult, it requires welding metal to the broken stud and turning it out. The heat from welding usually frees it from being stuck. When you replace the studs, use stainless studs to avoid this problem in the future.

Edited by Powerflite 2019-07-05 6:40 PM
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Powerflite
Posted 2019-07-05 6:42 PM (#584473 - in reply to #584466)
Subject: Re: Exhaust manifold removal



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If there is enough to grab onto (which is doubtful, they usually break at the interface between parts), heat it first with a torch or welder to break it free from the rust that's holding it.
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1960fury
Posted 2019-07-05 7:20 PM (#584477 - in reply to #584466)
Subject: Re: Exhaust manifold removal



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Never had to pull a head to remove a sheared off stud. Often there is a little protruding piece of stud left. This is usually enough, IF you are careful. Drill a nut (of the size that fits the stud) open with a large drill bit, but not quite, leave a little thread that is supposed to be "threaded" to the sheared stud. Then weld the nut to the stud and turn the nut IMMEDIATLY counterclockwise (may need a helper). This works even sometimes if the stud is flush with the head surface. Another method is to drill it out, mostly you will need a 90° drill adapter for this. Punch it in the center and drill the stud, in small steps going bigger, out. You usually don't have to drill it out to the max, as the stud will lose its stabilty long before you are getting close to the head material. There are left hand drill bits available for this, but these are usually not needed. If the stud is flush with the head or if very little is left, play it safe and drill it out, as once welded it is nealy impossible to drill.
The trick is, as with most old car repairs, do not rush. Even if you have to fabicate yourseld a guide that bolts to the head, so you can drill the stud out precisely, this is usually less time consuming and cheaper than pulling the head.

Edited by 1960fury 2019-07-05 7:31 PM
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imfinlay
Posted 2019-07-06 5:05 PM (#584501 - in reply to #584466)
Subject: Re: Exhaust manifold removal


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If only I could weld! I'm wondering if it's THAT hard to take the inlet manifold off (then I can get it blasted and painted nicely) and the heads off and get hardened valve seats fitted and the stuck studs removed. It doesn't look that bad in the manual, and I have a gasket set already.

Am I going to regret this?
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1960fury
Posted 2019-07-07 8:13 AM (#584514 - in reply to #584466)
Subject: Re: Exhaust manifold removal



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Depends. Usually one thing leads to another. If you want to enjoy this years cruising season, try to drill it out. I wouldn't drive without the stud, as an exhaust leak at the head usually makes the car perform badly.
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60 dart
Posted 2019-07-07 4:13 PM (#584521 - in reply to #584466)
Subject: Re: Exhaust manifold removal



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i've always made sure the break was as flat as possible , drill center start with a smaller bit than bolt size , usually 1/8 then up to a size where i just see threads . then i tap with the size of the last bit
til i get to original bolt size . in a lifetime of working on cars , it's never failed me yet -----------------------------------------later
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1960fury
Posted 2019-07-07 5:12 PM (#584523 - in reply to #584466)
Subject: Re: Exhaust manifold removal



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There are stud removal bits available. If they work there is no risk of damaging the thread as you don't have to drill it out to the max, but I never tried them. The thought of an ultra hard bit breaking off in the head stud fragment scares me off.
The problem is, if you make the pilot hole too small, there is the risk of breaking of the bit, if you make it too big, you expand the stud fragment in the head. Not good. The ultimate fiasco would be both, a broken stud removal bit in an expanded stud fragment in the head

https://www.ebay.com/itm/5-Pce-Damaged-Screw-Bolt-Stud-Remover-Extra...

Edited by 1960fury 2019-07-07 5:18 PM
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imfinlay
Posted 2019-07-07 5:38 PM (#584526 - in reply to #584466)
Subject: Re: Exhaust manifold removal


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I have some extractor bits, like you I'd be concerned about breaking one off. I have some stud removal tools which are supposed to grab what's left. I'll get some pics up here when I have the manifold off - just had to order some new sockets online as I only had a long 5/8ths which won't get onto the downpipe bolt. The other one was 15mm... that one came off with a breaker bar and some enthusiasm.
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imfinlay
Posted 2019-07-07 5:38 PM (#584527 - in reply to #584466)
Subject: Re: Exhaust manifold removal


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Location: London, England
I have some extractor bits, like you I'd be concerned about breaking one off. I have some stud removal tools which are supposed to grab what's left. I'll get some pics up here when I have the manifold off - just had to order some new sockets online as I only had a long 5/8ths which won't get onto the downpipe bolt. The other one was 15mm... that one came off with a breaker bar and some enthusiasm.
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imfinlay
Posted 2019-07-07 5:38 PM (#584528 - in reply to #584466)
Subject: Re: Exhaust manifold removal


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Posts: 487
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Location: London, England
I have some extractor bits, like you I'd be concerned about breaking one off. I have some stud removal tools which are supposed to grab what's left. I'll get some pics up here when I have the manifold off - just had to order some new sockets online as I only had a long 5/8ths which won't get onto the downpipe bolt. The other one was 15mm... that one came off with a breaker bar and some enthusiasm.
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imfinlay
Posted 2019-07-09 12:00 PM (#584620 - in reply to #584466)
Subject: Re: Exhaust manifold removal


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Location: London, England
Well that will teach me to refresh the page! Sorry about the repeated posts. Anyway, called my local cylinder head specialist. He can fit hardened seats, lap the valves, remove the studs and generally clean both heads up for about 500 pounds, about $625. I think that's pretty reasonable, with him doing the head disassembly. I guess I could pull the rocker shafts but I'd rather spend time on other stuff. Turnaround in a week. I got the downpipe off eventually, the left side one is next - and thats still got studs in the downpipe connector so I see more shearing in my future
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1960fury
Posted 2019-07-09 4:09 PM (#584632 - in reply to #584466)
Subject: Re: Exhaust manifold removal



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If the engine was running trouble free, I wouldn't touch it, unless you know the guy, trust him 100% and he is familiar with Mopar V8s of that decade. I'm running w/o hardened seats for about 25 years w/o any problems. After ages in the hobby I know often the problems start after such actions. $625 vs $20 for a couple of quality drill bits. But it is your car and your money. I wish you luck anyway.

Edited by 1960fury 2019-07-09 4:11 PM
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imfinlay
Posted 2019-07-10 6:31 AM (#584649 - in reply to #584466)
Subject: Re: Exhaust manifold removal


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Location: London, England
It wasn't. I think the issues were related to the carb and the stuck heat riser flap - possibly carbon in the intake. That's why the exhaust is coming off, and I want to repaint the whole thing too. The company's Facebook page shows they've worked on Jensen V8s, which are Mopar 440 engines, Jag XK engines and other classics. https://www.facebook.com/PeterboroughCylinderHeads/ if you want to look.

I don't trust my ability to drill a straight hole
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imfinlay
Posted 2019-08-26 5:46 PM (#586596 - in reply to #584466)
Subject: Re: Exhaust manifold removal


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Location: London, England
Well I finally got the drivers side manifold off. There were some odd castellated nuts on the downpipe, one came off with an Irwin nut remover, the other god ground off (eventually) with a stone on a Dremel. Six of the manifold nuts were 1/4 Whitworth (just under 5/8) and two were 9/16! I got some Dorman studs which are supposed to be the right spec, but they're a bit longer than the ones in the motor - which should be ok - and the nut part has a slightly different thread. I'm guessing they're BSW instead of UNC. It's odd, because the car came to me from Virginia and I don't see how the studs could have changed! Anyway, I can get the manifold blasted now and get on with taking off the inlet.
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