Maybe a little help please for my 66 dart, slant that I just swapped to super six. The manifolds, I have triangle washers everywhere except top center and 2 top outer studs. Is that ok? Also the top center is thick round washer, but normal nut. The 2 outer top, are normal nuts and conical washers.
I read all the articles, and pictures. Talk about castle nuts? self centering nuts? I don't have any of that. help? Do I need to find other washers? or am I good?

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66 dodge dart 270, 225ci, 3.7l, L6

Right, on the two upper extremes there is a thick brass washer and a special lock nut (5/16-24 just like the other nuts). If you go to McMaster Carr website, look for "locknuts" and in that section scroll down to "stainless steel flex-top locknuts" part number 91839A130 The flex top, split portion, goes into the center of the thick brass washer. The split ends grip the stud, and when it's screwed into the center of the brass washer it locks the nut into place. The brass washer ID needs to be larger than 5/16", say about 3/8 or so so that the split portion of the nut fits into it. The closest that I could find on Mcmaster was part number 95395A310, the OD is about right, but the ID is 1/4" so it would need to be drilled out.

The regular brass nuts are part number 92676A430.

The middle top one has a circular cupped washer, the cupped end goes toward the manifold and a regular brass nut goes there.The cupped washer at the center top is a countersunk washer, the closest I could find to that was part number 98466A030, but the OD might be bigger than the factory one.

Brian

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In the upper left corner of the picture, you can see the split (acorn) nut inserted into the thick brass washer, locking it in place - that assembly goes on the two upper, left and rightmost studs. In the center right is the round cupped washer, that goes on the center upper stud, cup side toward manifold, then a regular brass nut goes on.

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Just to add a couple of details for future researchers:

More discussion HERE on the oddball nuts and studs, with sources.

Also, if you use the nice, thick Remflex gasket and the later, thicker triangular washers, the studs may be too short to allow easy installation.

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"When you find a big kettle of crazy, it's best not to stir it." - Pointy-haired Boss

1964 Valiant V200, 225/Pushbutton 904
BBD, CAI, HEI, LBP, AC, AM/FM/USB, EIEIO

Good point on the thicker triangle washers plus Remflex.

If you need a slightly longer stud, McMaster Carr part # 94358A270 has 1/2" on the coarse thread (same as OEM stud) and 1" (as opposed to factory 3/4") on the fine thread side. I use these, they are black oxide coated with a minimum tensile strength of 150,000 psi and minimum Rockwell hardness of C38. They have a 1/8" hex for installation as well.

brian

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Thanks for the info. Those brass Dorman nuts are real hard to find. No one local has it. Then Amazon has it for $18?

I did find a stud at OSH, but something about it seemed strange. It was $4. When I tried to install it, it seemed to want to just screw all the way into the hole, deeper than the original one.

What about using the conical washers at the ends?

Also I read all the other articles about this, but I would be concerned at using lock nuts on the ends, as that increases the chance of breaking a stud if I need to remove the nut, right? Also it would probably unscrew the stud (if it didnt break) , and then trying to remove a locknut from a loose stud might not be easy?

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66 dodge dart 270, 225ci, 3.7l, L6

McMaster Carr has the brass nuts, the acorn nuts and the studs, it's just that thick brass washer that goes with the acorn nut and the cast iron washer that goes center top that are hard to find commercially.

When you install the studs, you seal them, because they go into the water jacket. I use Permatex 59214 high temperature thread sealant, let it set up overnight before installing the manifolds. The studs shouldn't come loose when you remove the nuts at the ends, mine didn't. Just make sure the hole and stud threads are clean before you install the studs. They stop naturally as there is only 1/2" of coarse thread on them to screw into the head.

Those McMaster studs that I quoted above won't break. Also they have the hex in the end, so you can use a hex wrench in them when you're loosening the nut to keep them from turning. The locknut sometimes sticks in the brass washer and they come off as a unit (see bottom left of picture above). That's OK, after they're off the stud, you can punch the nut free of the washer and reinstall washer then nut. The nut centers in the washer.

Brian

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Just to be clear: The brass washers for the end are not conical washers, they just have a conical hole to work with the slotted portion of the flex top nuts. The faces are flat.

A conical steel washer (convex on the manifold side, concave on the head side) is used on the middle stud. It's used with a normal nut.

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"When you find a big kettle of crazy, it's best not to stir it." - Pointy-haired Boss

1964 Valiant V200, 225/Pushbutton 904
BBD, CAI, HEI, LBP, AC, AM/FM/USB, EIEIO

Great info guys. So I did more work on the manifolds today, I determined that I do have 2 brass type washers, though there is no inset on them, I used them at the ends on top, with a normal nut. I dont have any lock nuts like you mentioned, and I see conflicting reports of how those nuts go on, some say castle part goes into the washer, while others say castle goes away from washer.

I did put a conical washer and normal nut on the top center. The whole 10lbs torque , is that something that has to be checked after a few weeks? Cause I had just install this manifold last week, to 10lbs, and today when I removed the nuts, they weren't very tight.

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66 dodge dart 270, 225ci, 3.7l, L6

The acorn nuts do go into the brass washers. My washers don't have a tapered hole either, but the split (locking) part of the nut does fit into the hole and self centers. I provided a McMaster part number above for that acorn nut in stainless.

The torque on the nuts is light so that the manifold can "float", they are not supposed to be clamped down hard, just enough to seal to the gasket. If you use a Remflex gasket there is more crush to accomodate slight warpage in the manifold.

See Doug Dutra's tutorial here: http://www.slantsix.org/articles/manifo ... unting.htm

Also note, Doug says that the older service manuals called for three of the conical washers but newer specs say just the one at the top center (the other two are triangle with brass nut).


Brian

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The studs are fine thread for a reason, it helps prevent the brass nuts from walking loose. You can check them occasionally if you want, but I don't put any thing on the threads and mine don't seem to loosen up over time - that is with new studs and nuts, all clean, no rust to hold the nuts in place, still they don't seem to loosen. Of course, if you hear a "tick, tick, tick" of an exhaust leak, check those nuts first, very likely loose.

brian

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FYI, if you have airplane buddies, a standard stainless steel self-locking aircraft nut (AN363C-) fits also, upside down, for the 2 end nuts. P

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"Louise", a 1976 Dart Custom project, (now sadly reverted to being just an "organ donor" to our other project Darts.)

Talking about castle nuts, what do you think about this source?
http://www.ebay.com/itm/Mopar-Slant-Six ... d4&vxp=mtr


Not acorn style, but are castle

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66 dodge dart 270, 225ci, 3.7l, L6

McMaster Carr.

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1964 Dart GT