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manifold nipple

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geronimo

Posts: 11

Joined: Sat Oct 02, 1999 12:01 am

Post Thu Jun 22, 2000 5:43 pm

manifold nipple

hello everyone, i'm having an problem with the intake port on my rear head. the threaded area of the head where the manifold nipple threads in at are badly damaged, the place where the rivet was orginally set had been broken off and then repaired (glued together) with some type of epoxy . the front head manifold nipple is still intact,and i want to use the orginal intake manifold. i plan on getting an replacement manifold nipple and locite it in place when i fit the intake manifold,and try to avoid setting another rivet. i'm not sure on which locite to use or if i should use some type of epoxy,i think that the locite would help seal the threaded area, but not sure it will hold up to tighting and untighting of the manifold nut after its been in use. i would appreciate your help on this fix.
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Cotten

User avatar

Posts: 2675

Joined: Thu Sep 30, 1999 12:01 am

Location: Central Illinois, USA

Post Fri Jun 23, 2000 2:28 am

Geronimo! You are faceing one of the most frustrating of tasks, particularly if you haven't the tooling. I can post you a photo direct of how a fresh nipple has bben whizer-wheeled to make a tap for cleaning threads after brasswork. Loctite-style sealers don't seem to cut it; I use a white bonder called Seal-Lock that is used for retaining valve seats. Still, this won't fill gaps. JB Weld works for a minute. The purpose of the rivet is to prevent the nipple from walking back out with the nut. It is embarrassing when it does, as you must pull a head to do anything about it. The rivets should be custom cut to a reamed hole. I use a cam-like anvil that twists into the nipple with a wrench to force the rivet outward for peening. I check all installations with 15psi and soap suds. More often than not, I pull my hair out.
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rein

Posts: 109

Joined: Thu Mar 09, 2000 1:01 am

Location: holland

Post Fri Jun 23, 2000 4:17 pm

i have the same problem right now with a 39 head,,and solved it the same way i did before.Using the existing thread i turn in a new nipple, coated with coppa-slip,its copperpaste that allows tightened bolts to loosen up easily, used in refineries and so on.I turn in the nipple using the manifoldnut and bushing.When its really tight i take off the nut, and start building up the tornaway part using mig welding.I try to avoid direct contact with the nipple as much as possible,aiming at the head material,very short moments, and use low amperage.The coppaslip more or less prevents welding the nipple itself.After grinding the irregularities i drill a new hole for the pin,going thru the bushing of course,put in the pin from the inside, and using high amp.(150) i spotweld it on the outside.It looks good,keeps the nipple in its place,and when the nipple accidently gets welded to the head, bad luck,next time you need to replace it(for what, and in how many years?)Break it out, and do the same again.
I do the same with partial torn out headbolts.
I know this works fine for me, but if you have the tools and experience maybe its your solution as well
good luck.

best thing is to use a dremel for bringing back the pinhole instead of drilling due to hard welding material,After rebuilding the gap with low amp, you should cover it all wih high amp welding,this makes it melt all nicely, and no danger of adhering to the nipple

[This message has been edited by rein (edited 23 June 2000).]
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geronimo

Posts: 11

Joined: Sat Oct 02, 1999 12:01 am

Post Sat Jun 24, 2000 3:46 am

when i first disassembled the intake manifold the rear nipple back right out when i'd turned the manifold nut, along with strings of orange high temp silicone. i knew then this was trouble.

the piece that has been glued together stills feels & looks soild, i would like to repair it without wielding, though it is an option.

cotten, i'm sorry but i don't understand what you meant by brasswork, both heads are completely disassmbled. thats an good idea on trying to restore threads. could cold rolled steel be used as an rivet?. also would there be an problem setting the rivet ,almost 90 deg. up close to the first vert. cooling fin? i would guess that the rivet would have to be 1/4" longer or so, to go through the thicker portion of the head.

the nipple i removed had two holes drilled 180 apart where the rivet would be, i'm assuming that an new nipple would be blank, and i would have to screw it in until the threaded part (for the manifold nut) turns up against the head, and then pin it.

i like the idea of leak testing the nipple, when do you try it, when the head is assembled and mounted to the cylinder?.

thanks for your time gentlemen.
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Cotten

User avatar

Posts: 2675

Joined: Thu Sep 30, 1999 12:01 am

Location: Central Illinois, USA

Post Sat Jun 24, 2000 12:09 pm

By 'brasswork', I meant braze repair, usually with a silicon-bronze rod, or nickle-silver for touch-ups or wicking into cracks.
Your choice of materials for the rivet just depends on malleability, although you don't want it so soft as to allow the nipple to move. Moving it's location is a question of whether or not you will still catch enough of it to secure it. It is best to stay from the mating faces of nipple to head, as the cast iron likes to split outward.
The fresh nipples from Colony are excellent, however the internal threaded section is usually ~.060" too long. This must be cut back to allow these faces to fully meet (the o-ring just won't stay on place, and would be temporary if it did.)
I usually 'pot' in the new nipple with Seal-Lock and let it set up overnight before I fit the rivet, and I use the sealer on it also. The leak testing is always easier on the bench, particularly since success isn't always assured when the threads have been damaged. I have had luck sealing remaining pinholes by applying vaccuum and drawing the sealer into the leaks.
After all of this, your biggest worry is that you might twist it all loose anyway trying to get the damn brass ferrules to compress; I put 15psi on the manifold WHILE I install it so I can watch the soap suds and only torque up as little as necessary for a seal.

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