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Studs/Nuts for FMC 440 Exhaust Manifold
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hemi354az
Posted 2017-09-29 1:50 AM (#5031)
Subject: Studs/Nuts for FMC 440 Exhaust Manifold


Extreme Veteran

50025
Location: Scottsdale, Aridzona
Mopar 440 Exhaust Manifold Bolts ? Bolts ?? BOLTS ??? There are NO BOLTS !!! Only STUDS !!!!
The gas engine that comes stock in a FMC 2900R has cylinder heads that come with SIX (count them - 6) exhaust STUDS, that are all in a straight line, all the same size, in each head. The tapped (3/8-16) holes in the head are "wet". They go all the way into the water passages of the head. If an exhaust stud comes out . . . the coolant will come out that stud hole.

If you are changing manifold(s) or gasket(s) and instead of a nut . . . you start removing a BOLT . . . STOP ! Quickly put it back in snug. If you don’t, your work area and you will be covered in engine coolant. Some previous owner (PO) of YOUR FMC did exhaust manifold work and pulled a stud out and instead of replacing it with a stud . . . he grabbed a bolt. My #120 had BOTH manifolds attached with 12 BOLTS, 4 long with washers, and four short ! See - http://www.fmcowners.com/mbbs22/photos/show-album.asp?albumid=177&p... and http://www.fmcowners.com/mbbs22/photos/show-album.asp?albumid=177&p...
Before proceeding . . . drain the engine coolant (remove the lower hose at the radiator) into a suitable container for reuse. Then pull the bolt out and proceed. It is also common for the nut to corrode and stick to the stud and cause it to come out when "removing" the nut. If that occurs . . . turn it back in quickly, and drain the coolant before proceeding. Looking thru both FMC Websites . . . coolant dripping or running out cylinder head stud holes is very common.

The exhaust manifold studs used on the Chrysler 440 cylinder head are 3/8-16 thread on the end that goes into the head, and 3/8-24 on the end that sticks out, and are 2 inches length overall. They are made from high quality steel as they get hot and must restrain and still stretch as the manifold expands as it gets orange from the 1600° F exhaust gas at wide open throttle.
The studs originally used in wet holes have INTERFERENCE FIT threads used at the hole end. See the left stud - http://www.fmcowners.com/mbbs22/photos/show-album.asp?albumid=177&p...
That is why they usually do not come out. But they are very hard (impossible ?) to find. To remove a stud from the cylinder head . . . jam two good nuts tightly together on the stud threads that are sticking out (see - http://www.fmcowners.com/mbbs22/photos/show-album.asp?albumid=177&p...) . . . then turn the inner nut CCW to hopefully unscrew the stud. If that won’t work . . . good BIG vice-grips, and start looking for a new stud. Dorman sells (eBay, RockAuto, Summit, AutoParts Stores) three studs, with 3 lock washers, and 3 nuts in a package as Part # 03103 for $5-8. See - http://www.fmcowners.com/mbbs22/photos/show-album.asp?albumid=177&p...
Lock-washers on exhaust nuts are useless, as after a couple good heat cycles. . . they no longer have the “lock” twist in them but remain flat. I personally don’t like the nuts in the Dorman kit. But the studs are OK.
A better stud is available - http://www.partsmix.com/products/1974-79-big-block-440-truck-exhaus... – but, this may be the same stud offered at Ace Hardware in their Fastener Boxes. All the Ace Stores do not have the same items . . . but many have a tray labeled exhaust studs that MAY have the 3/8 , 2 inch length, with the 16 and 24 threads, at 2$ or so each. Get a couple spares.
See Ace stud on left and Dorman on right - http://www.fmcowners.com/mbbs22/photos/photo-thumbnails.asp?albumid...

Clean all the threads and flat machined surface of the head with a wire brush. If replacing stud(s), if you choose, run a 3/8-16 thread CHASER (NOT a tap, a thread CHASER) in the cylinder threaded hole. Clean it out with a wire bristle hole brush. Install the new stud using LocTite 272 HiTemp Thread Locker. It comes in various size tubes/bottles priced accordingly. Or you may use the Permatex equivalent to the LT 272 as they are both made by the same Corp. PT is Lt in USA. Tighten the new stud with the two 3/8-24 nuts jammed tightly together, then turn the outer nut CW till the stud is tight against the un-threaded shoulder (about 28-32 ft-lbs torque). Remove and replace or install studs (where there were bolts) as needed. Now you head should have 6 studs firmly locked, and ready for the manifold. See - http://www.fmcowners.com/mbbs22/photos/show-album.aspalbumid=177&ph...
If you choose to use a gasket between the head and manifold . . . the copper ones seem to last the longest.
Liberally coat the threads of the exhaust studs sticking out with ANTI-SEIZE Compound. This is very important. You can use - http://www.neverseezproducts.com/purenickel.htm(8 oz brush top should last you a long time) or similar HIGH TEMP Anti-Seize Compounds by LocTite/PermaTex or others.

There are all kinds of 3/8-24 nuts to go on those studs to hold your manifold tightly to the head/gasket. See - http://www.fmcowners.com/mbbs22/photos/show-album.asp?albumid=177&p...
Those are all 3/8-24 nuts that are SELF LOCKING and suitable (except for the NyLoc one) for exhaust manifolds. I prefer a good grade 8 hi-temp self locking nut that has a smooth flange made onto it so that no washer is needed. These are the ones I use - http://www.flangebolts.com/shop/3-8-24-hex-flange-locknut-grade-g-p... . You need eight nuts for the pair of manifolds.
The two middle studs have to have SPECIAL BARREL NUTS for the Center Dump Exhaust Manifolds that were used on the FMC. See - http://www.fmcowners.com/mbbs22/photos/show-album.asp?.albumid=177&...
The two center stud holes are oversize to accept these long reach barrel nuts that go down to the flange that is made in the casting down in those two holes. Those two flanges are the same thickness as the tabs on each end port of the manifold, so all the studs can be the same length. If you see a hex with a washer under it . . . that is a BOLT and coolant will come out if you remove it. If you see a little space around the barrel below the hex at the two center fasteners . . . then that is the correct barrel nut. See - http://www.fmcowners.com/mbbs22/photos/show-album.asp?albumid=177&p... But that barrel nut sometimes also corrodes to the stud and pulls it out when you remove the barrel nut.
You need four barrel nuts - http://www.partsmix.com/products/4pcs-exhaust-manifold-long-tube-nu... - for the pair of manifolds . . . or you can find the LONG ones on eBay or other Mopar Parts suppliers on the Nets. Liberal application of the anti-seize compound to the studs will prevent the corrosion/sticking that occurs on these FMC 440 exhaust manifold fasteners.

Place the gasket, then the manifold, on the studs and start the outer nuts, then the inner of the outer nuts, then carefully start the barrell nuts on the studs making sure you have got them threaded correctly, then hand tighten all of them, then finish with 32-35 ft-lbs torque, center out in a circle. Hook up the rest of the exhaust headers, and install the spark plugs and wires, (hopefully the ceramic end ones. See on Low Manifold picture - http://www.fmcowners.com/mbbs22/photos/show-album.asp?albumid=177&p...) with the wires going around each END of the head. Then refill the engine coolant, remembering to top it off in the burp can after it cycles the thermostat the first few times. The studs Loctited into the heads, and the correct barrel and other self locking nuts onto liberally applied anti-seize compounded studs should keep the manifolds tight, and the coolant contained in the heads for a loooooooooooong time, but allow the nuts to be removed easily when one of the manifolds cracks or you need to remove both for other reasons. Same procedure for studs and nuts, if you are fortunate to have a set of the low manifolds (See - http://www.fmcowners.com/mbbs22/photos/show-album.asp?albumid=177&p...), except you do not use the barrel nuts (you could, but they would be sticking out).
Exhaust ON ! Lou #120
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fmc708
Posted 2017-09-29 3:49 AM (#5032 - in reply to #5031)
Subject: Re: Studs/Nuts for FMC 440 Exhaust Manifold



Veteran

100
Location: Soquel, CA.
Excellent write-up and photos, Lou. I actually understand this now.
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B. Sitton
Posted 2017-09-29 8:47 AM (#5033 - in reply to #5032)
Subject: Re: Studs/Nuts for FMC 440 Exhaust Manifold


Extreme Veteran

100100100100
Location: Ignacio Colorado
Definitely use the heavy copper manifold gaskets. The plug wire boots get burned by the leaking of the exhaust gas by a burned out gasket. The ceramic boots are extra insurance but no leaks is the key.
Bill
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hemi354az
Posted 2017-10-22 11:24 PM (#5109 - in reply to #5031)
Subject: Re: Studs/Nuts for FMC 440 Exhaust Manifold


Extreme Veteran

50025
Location: Scottsdale, Aridzona
Found Source for genuine inteference fit exhaust studs for FMC 440 - http://www.clipsandfasteners.com/3_8_1_Sae_3_8_5_8_Uss_X_2_Overall_...
$8.40 for 10 each, and $6-7 shipping/handling to me in Aridzona. Enlarge photo . . . and see that the 3/8-16 end has the FLAT TOP on those threads.
Hot damn, the genuine article !
Stud ON ! Lou #120

ps: this Link - http://www.clipsandfasteners.com/ - has LOTS of the weird small parts that are in every piece of Detroit Iron. Bookmark them !
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hemi354az
Posted 2018-11-05 11:14 PM (#6000 - in reply to #5031)
Subject: RE: Studs/Nuts for FMC 440 Exhaust Manifold


Extreme Veteran

50025
Location: Scottsdale, Aridzona
You might be needing one or a pair of these in the next year or two . . . very cheap with Free Shipping -
https://www.ebay.com/itm/Exhaust-Manifold-Left-or-Right-for-Dodge-D-...
Quietly ONWARD ! Lou #120
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hemi354az
Posted 2023-02-08 5:27 PM (#8130 - in reply to #6000)
Subject: RE: Studs/Nuts for FMC 440 Exhaust Manifold


Extreme Veteran

50025
Location: Scottsdale, Aridzona
As you discovered . . . that link is long deleted. I have 2 PAIR of the Low Exhaust Manifolds that fit "your" 440 powered FMC . . . that will prevent overheating the valve covers and gaskets . . . and BAKING the oil inside the valve cover. I do NOT have the Spark Plug Heat shields . . . just the LOW MANIFOLDS. They are $600 Dollars American (cash) a PAIR, FOB my garage in Scottsdale Aridzona. You pick the "pair" you want. If interested Ph # is listed in Member Roster. C'mon Down ! Lou #120

Please see Bill #902 Sitton's pictures of these LOW MANIFOLDS at - http://www.fmcowners.com/mbbs22/photos/photo-thumbnails.asp?albumid...

Edited by hemi354az 2023-02-08 5:36 PM
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