Exhaust manifold nut problem--need ideas

[61farnham]

Ha, just gone through this myself with the studs whilst tracing a pinking/knocking noise in the engine on acceleration which i've hopefully traced to a leaking valve cover combined with a loose intake manifold. The valve cover had a slight leak on the top edge just under the intake manifold which not being sealed properly sucked the oil into the rear two cylinders on accelerating causing air/fuel mixture to be wrong hence the pinking, fingers crossed it's just a case of new gaskets and sealant I'll know when it's back together.

 

Anyhow back to the manifold studs and with mine looking not the best I needed to replace them, according to my P15 parts book there were three different lengths of stud used,

4 no. 1-15/16" long

7 no.  1-11/16" long  

2 no.  3-5/16" long

with the 4 no 1-15/16" going at each end of the exhaust manifold with the conical nuts and washers on.

 

The best match I could find was as follows

Dorman 675-003 at 2" long

Dorman 675-070 at 1-3/4" long

Dorman 675-080 at 3-3/4" long 

 

These all have the 3/8" unc threads at one end and  3/8" unf threads at the other as per original spec.

 

I've  just ordered them from Rockauto so not fitted yet but i can see no reason why they shouldn't work ok.

They all only come in boxes of ten but their cheap enough.

Here's a quick to scale sketch I did to show comparsion between them.

 

 

Edited January 14, 2020 by 61farnham

[Sniper]

Thank you very much.  Did you manage to find a source for the conical washers and nuts?  I was looking at McMaster Carr the other day and wasn't finding what I needed there.

 

Thanks again

[RobertKB]

4 hours ago, Sniper said:

Thank you very much.  Did you manage to find a source for the conical washers and nuts?  I was looking at McMaster Carr the other day and wasn't finding what I needed there.

 

Thanks again

 

Best source for these are old engines that are being discarded or used for parts. Any time I come across such an engine I take as many conical washer and nuts as possible. They are specific to these engines. I have a lot of these washers and nuts that I have collected over the years. Your best bet is to go to the classifieds and post a wanted ad for them.

[61farnham]

There's a seller on ebay with just the nuts, type in "1930's 1940's 1950's mopar exhaust manifold nuts" or I found another ebay seller mopar-direct, type in "1946-1959 Plymouth, Dodge manifold hardware rebuild kit",  with the whole kit plus gaskets for $70 but they wanted $85 to ship to me in the UK and when you add on 20% import duty + tax it would have been almost $200 for the studs/nuts and washers, i run a Plymouth not a Rolls Royce?.

Vintage Power Wagons sell the full kit as well for $60 without the gaskets but I never got a reply from them for a shipping quote.

 

I'm envious of of that manifold you've on order if I didn't already have a tall Edmunds to fit I'd be next in line.

 

Regards.....

[Sniper]

I think my problem is I can't see paying $70 for the kit when I could buy the equivalent of 4 kits for that money going with the Dorman stuff.  Thanks to the help here and some research on my own I have numbers for the studs, washers and brass nuts except the conical stuff.   If I find a source I will share it.

 

I still have the conical nuts and washers on my current manifold.  So I could recycle those, but like the boneyard donors they'd be ugly looking when all the other hardware is new.  I suppose I could sand blast them, but I need a sand blaster.  Then I would also need a compressor big enough to feed the sandblaster.  Of course I'd need a new electrical line run to supply the compressor at which the inspector will want, at the very least, the feed to my house brought up to current code and knowing my luck the breaker panel and house wiring too.  At that point I may as well just spend the $70 for the kit. 

 

It's a vicious cycle.  All my Plymouth money is currently earmarked for other things and I don't have an endowment, lol.  Now if only Ed McMahon would deliver my check I'd be set.

[Sam Buchanan]

58 minutes ago, Sniper said:

I still have the conical nuts and washers on my current manifold.  So I could recycle those, but like the boneyard donors they'd be ugly looking when all the other hardware is new. 

 

A small sheet of sandpaper, maybe a small steel brush, and a piece of Scotchbrite pad...........

[Sniper]

I'm a natural pessimist, lol.  This way I am never disappointed.

 

I went out and looked at the hardware.  Someone's been there before and reinstalled the stuff incorrectly, I believe.  They have the conical castellated nuts installed on the four outer INTAKE manifold studs, with the cone facing out.  The four outer EXHAUST studs have the washers in them, but regular nuts.  If I understand correctly, the conical nuts and associated washers go together and on the four outer EXHAUST studs? 

 

I found an NOS source for the funky nuts, maybe.  Frank Mitchell, fmmpr on Ebay.  I sent a question asking if he had the washers, too.  We shall see.  Though to be honest i haven't heard good things about him over the years.

[Merle Coggins]

Yes, the 4 conical nuts and cupped washers go on the 4 outer most studs. There are also a few thick, heavy, washers that go under the nuts where they span the intake/exhaust manifold stud gap. The rest are smaller flat washers and nuts. 

 

If you invest in one of those vibratory tumbler/polishers you could polish your nuts to your heart’s content. ?

[Sniper]

Man, as a sailor I am really conflicted, lol.

 

Good idea on the tumbler, I could use one for other brass things I have as well.

 

My daughter came down for Thanksgiving and was asking about an ultrasonic cleaner for her husband (he's a cop and had to work) for his stuff that goes boom.  So we researched some of them and I ended up buying a small ultrasonic cleaner after she went back home for my .45.  For Christmas my daughter got me a big ultrasonic cleaner.  I still cannot pick up a clue.  At least now I can do my AFB's in the one she got me. 

[Bryan]

On 1/14/2020 at 10:40 AM, 61farnham said:

Anyhow back to the manifold studs and with mine looking not the best I needed to replace them, according to my P15 parts book there were three different lengths of stud used,

4 no. 1-15/16" long

7 no.  1-11/16" long  

2 no.  3-5/16" long

with the 4 no 1-15/16" going at each end of the exhaust manifold with the conical nuts and washers on.

 

The best match I could find was as follows

Dorman 675-003 at 2" long

Dorman 675-070 at 1-3/4" long

Dorman 675-080 at 3-3/4" long 

 

 

 

 

Would this be the same for the D24 Dodge? 

[61farnham]

1 hour ago, Bryan said:

Would this be the same for the D24 Dodge? 

Worked ok on my P15 engine so I don't see why not. Vintage Power Wagons only sell one kit so I assume all Mopar 23" blocks use the same length studs.

Edited November 28, 2021 by 61farnham