Slant 6 Exhaust Manifold Washers

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klumppm1

klumppm1

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I am replacing a cracked exhaust manifold on my 1965 slant 6. I found I was confused as to how the washers are oriented, and where the three different types of washers go. So, I read a ton of posts, read my '65 Plymouth Service Manual, and spoke to an old MOPAR mechanic. Here is what I learned.
The middle-top stud gets the domed stainless washer and regular nut. Dome side faces up.
Each of the two outside-top studs get a thick brass washer and special slotted locking nut. Slots on the nut face down towards the brass washer. The inside diameter of the brass washer squeezes the nut onto the stud and keeps the nut in place.
All the rest of the studs get the domed stainless triangle washers and regular nuts. These washers also go dome side up. All nuts are tightened to 10 ft lbs. Hope this helps anyone who might be replacing an exhaust or intake manifold.

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Thats correct. When the manual says "cup side against manifold" they mean the concave (think 'caved in') toward manifold mounting ears. They could have said "cone side out to nut" and made easier sense of it. If you dont have the special serrated nut (flexloc ? FLEXLOC) that nests in the brass washer, you could use more triangles at the ends as that's what they did in later slants.
 
SlantSixDan regularly links a post on slantsix.org. Has good photos and I recall matches your desciptions, but "a photo is ...".
 
In the first post I agree with everything except.... The cone shaped washers are not stainless, just plain steel. Picky I know, but someone will try and find stainless because they had steel ones on their slant.
 
pishta said:
Thats correct. When the manual says "cup side against manifold" they mean the concave (think 'caved in') toward manifold mounting ears. They could have said "cone side out to nut" and made easier sense of it. If you dont have the special serrated nut (flexloc ? FLEXLOC) that nests in the brass washer, you could use more triangles at the ends as that's what they did in later slants.
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Pishta,
So NO round concave washers go on the bottom row in the middle? All triangle except the ends and the ONE top middle row concave?
I'm currently on this part of my engine rebuild so all help is appreciated.
 
Troub, check this from a far more knowledgeable guy than me...Dr. Dodge:
" The two acorn nuts go on the two top, outer end studs, with the coned shaped part of the nut fitting into the dished/conical part of the round brass washers. The center three studs (2 top and 1 bottom) get cup-shaped round cast iron washers, cupped faces towards the head. Everything else gets triangular butterfly washers. (Link to more manifold installation instructions)

Note that "later" SL6 engines came with only one round conical washer in the top center position, all the other were triangular type. This combination is also acceptable.." Read cheaper but a little tough to get going on the bottom rows.

instructions
 
pishta said:
Troub, check this from a far more knowledgeable guy than me...Dr. Dodge:
" The two acorn nuts go on the two top, outer end studs, with the coned shaped part of the nut fitting into the dished/conical part of the round brass washers. The center three studs (2 top and 1 bottom) get cup-shaped round cast iron washers, cupped faces towards the head. Everything else gets triangular butterfly washers. (Link to more manifold installation instructions)

Note that "later" SL6 engines came with only one round conical washer in the top center position, all the other were triangular type. This combination is also acceptable.." Read cheaper but a little tough to get going on the bottom rows.

instructions
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Perfect. Just what I needed. Thanks for this Pishta, very much appreciated!
 
I'll add that there is an article on slantsix.org which explains it with photos, that has been linked many times. If not installed correctly, the exhaust manifold can later crack. Those funky washers must have come from hard-learned lessons.
 
slantsixdan said:
And then there's this interesting recommendation from Chrysler:
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That is interesting. Thanks, Dan! I have a question somewhat related. You posted (I believe it was you) a link to McMaster-Carr for new manifold studs. Could you repost that here please? I feel like I am looking for a needle in a haystack on their site. Thank you.

Also, @krazykuda once Dan posts that link, IMO, you should turn this into a How To so the information will be saved. This is really good info that's hard to find otherwise.
 
Slant-6 manifold stud/nut links are
here. Install the studs with Loctite № 542 or № 592 on the ends that go into the cylinder head.

It is very much worth your while to get the good gaskets for the manifolds-to-head and intake-to-exhaust junctions.

General manifold mount info is in this article.

Exhaust manifold selection info is here, and because the only exhaust manifolds now available are '73-up type, and the '73-up factory chokes aren't necessarily what you need (and they're poopy even if they're a match for the carb you're running) you'll want the electric choke info that's here.
 
when I did the ones on the 65 Dart wagon, I found some replacement studs at a local Ace Hardware store...

That was so long ago, I can't remember the size etc...
 
The factory manual for 1976 cars list the manifold torque at 240 inlbs. [20 ft lbs]. The outer manifold studs use the special crush nuts and washers to limit the amount of 'squeeze' put on the end of the exhaust manifold, While using the same 20 ftlbs torque setting. This allows sliding movement.
 
I’ve only found them in full kits.
Ebay for $127 and Mopar Mall for $119
I’d go to a salvage yard if you’ve got any local that still deal with the old cars.
 
I'm pretty sure you can source them from McMaster-Carr.
 
RustyRatRod said:
Thank you!
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These links don’t work. I don’t need studs to the head I have all new . I’m asking about the 3 bolts only that hold the two manifolds together . I bought a full kit. But it did not come with these three bolts
 
Johnny71dusty said:
These links don’t work. I don’t need studs to the head I have all new . I’m asking about the 3 bolts only that hold the two manifolds together . I bought a full kit. But it did not come with these three bolts
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Hardware store. The one closest to the engine is supposed to be a stud, not a bolt. It's also one size larger than the two outboard bolts. The two outboard bolts are 5/16 and the stud is 3/8.
 
Question for rustyratrod. Didn't the original manifolds from the sixties use a 5/16 bolt in the center hole closest to the engine. Also would like your opinion on 1972 Dodge TSB section 11 on exhaust manifold replacement found in the Hamtramck registry.
 
townsend said:
Question for rustyratrod. Didn't the original manifolds from the sixties use a 5/16 bolt in the center hole closest to the engine. Also would like your opinion on 1972 Dodge TSB section 11 on exhaust manifold replacement found in the Hamtramck registry.
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All I've ever seen had a 3/8 stud there. That sure as HECK doesn't mean that's all they ever used, cause I ain't seen it all. lol Can you post a link to the Hamtrack?
 
townsend said:
See section 11 page 1 and 2 manifold replacement. The 1970 Hamtramck Registry "1972 Dodge TSBs" Page
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I go along with all that, but I would use extreme caution about the information on page #2. The two outboard retaining bolts are only 5/16 and they are pretty long. I would advise against going up to 20 LBFT. That's a lot of torque for a 5/16 bolt. I don't think I'd go any more than about 15. That's all I tightened mine to two years ago and they've gone nowhere yet.
 
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