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Exhaust Manifold New or Used
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Author:  Rodrju [ Thu Apr 30, 2020 8:05 pm ]
Post subject:  Exhaust Manifold New or Used
Hello All:

Working on a 1968 Barracuda Convertible with a 225—completely original 56k car--keeping it stock.

Two issues with the exhaust manifold have led me to the obvious conclusion its time for some attention.

Issue One
The heat riser mechanism was frozen solid. After some heat, penetrating oil (Castle Thrust is good stuff), I did manage to get it moving again. However, it is missing the rear spring, the front thermostatic spring seems suspect and there a fair amount of play in the shaft that prevents the door from moving freely. Seems like its seen better days. Car does has some minor cold drive-ability issues that I am working to solve and this likely does not help.
Issue Two
The car has an exhaust leak from under the hood---hard to tell where---I would guess it’s the manifold to pipe gasket—but I could be from the hot box area or the head itself---OR ALL OF THEM. All the head/manifold studs are intact. I very much doubt any of this has been resealed since 68.

Looking over some past posts on the forum I am aware of the superiority of Ramflex gaskets—they are available on Amazon.

Given the scope of work with this job…Does it make any sense to try and rehabilitate an old exhaust manifold (this or another) or acquire a new one?

The Dorman one is becoming harder to find and rather expensive---well over $300 these days.
ATP is available on RockAuto for $285
I did find this beauty on Amazon and eBay for significantly less --- $99. JJ Original Equipment

Not sure its worth the risk?
Has anyone tried on of these?
They all likely coming from the same Chinese factory... :(

I maybe able to source another used OE manifold with a working heat valve…but does that make sense…?

I realize any new manifold will require an electric choke---which is unfortunate given the mechanical one is brand new.

Thoughts and anything else to consider..?

Thanks
Author:  volaredon [ Thu Apr 30, 2020 9:13 pm ]
Post subject:  Re: Exhaust Manifold New or Used
there are plenty of good used exhaust manifolds to go around. I just had to find one for my pickup. The 1st one was hard to find and all I needed, but once I found it, they seemed to fall out of the wood work. When I was looking I was advised by several here NOT to go get one of those $100-ish Ebay ones... better with an original than one of those, and just to see "if my engine would run" I wasn't gonna spend Dorman money on one. ask around here, Im sure someone has at least 1 laying around.... somebody, I think it was member "and739" offered me one for a very reasonable price, about the time I found one in a local junkyard for about the same as shipping would have cost…..
Author:  Tim Keith [ Thu Apr 30, 2020 10:16 pm ]
Post subject:  Re: Exhaust Manifold New or Used
I always get a kick out of reading the Amazon reviews, its as if the items or the reviewers come from different planets. You want to see someone say something negative, that's human nature. But you prefer that the comments not be be all over the domain of possibilities, or in this case the Dorman.

Many ugly and poorly finished casting can be made to work, I hate to pay a lot for one like this. If you have some time, post on Craigslist or Facebook Marketplace and parts will come out of the woodwork, someone even might give you a complete motor. I create alerts on local self service salvage yards and always check out a new arrival of a slant six era Mopar. You can create alerts on craigslist too.
Author:  slantzilla [ Thu Apr 30, 2020 10:21 pm ]
Post subject:  Re: Exhaust Manifold New or Used
A guy posted a picture of the $99 one off E'Bay. It was ugly.

If yours isn't cracked take it to a machine shop and have it milled flat. There are kits available for the heat riser.
Author:  SlantSixDan [ Fri May 01, 2020 10:02 am ]
Post subject:  Re: Exhaust Manifold New or Used
Quote:
There are kits available for the heat riser.
…as expensive and difficult-to-find NOS, yes. As off-the-shelf parts, no.
Author:  Rodrju [ Fri May 01, 2020 11:47 am ]
Post subject:  Re: Exhaust Manifold New or Used
Agreed.

I have not been able to find any on-the-shelf repair parts for the heat riser.

Now that its loose, it seems the lack of the rear spring seems the main issue. I think its allowing the shaft to move too much and jamming the door at times.

The manifold itself does not appear cracked.

Thanks for the feedback...I'll try see what I can do with finding one locally or getting this one back in shape before going with one of the new options.
Author:  Joshie225 [ Fri May 01, 2020 11:50 am ]
Post subject:  Re: Exhaust Manifold New or Used
The Dorman manifold is $196 at Rockauto.com before the 5% discount.
Author:  DadTruck [ Fri May 01, 2020 8:17 pm ]
Post subject:  Re: Exhaust Manifold New or Used
Not that I need one, but I have found it odd that no one services the spring / damper for the exhaust manifold. Certainly that system was not unique to Chrysler ? Any chance that some other OE replacement spring would work? Or are none of the manifolds serviced with replacement springs and baffles?
Author:  Rodrju [ Fri May 01, 2020 9:29 pm ]
Post subject:  Re: Exhaust Manifold New or Used
Joshie225-

Thanks for the heads up. Searched Rock Auto yesterday AM and showed the Dorman unit as unavailable.

$196 (and the 5%) is nearly $100 less than any other site...most are over $300. My local independent parts supplier was also best case $300. I'm thinking that may be a limited production part these days. Rock Auto always seems to bite you on the shipping though....
Quote:
I have found it odd that no one services the spring / damper for the exhaust manifold. Certainly that system was not unique to Chrysler
I Agree. I was not able to find much to support servicing the heat riser. This is what concerns me the most about re-installing the one I have. Why go to all the effort to have a poorly or non-functioning heat value? I know its missing one spring and the other is suspect...

Given the price on the Dorman I decided to go new this time. Ordered Ramflex gaskets as well. Hopefully we can get everything sealed nicely...

Thanks for the input
Author:  SlantSixDan [ Fri May 01, 2020 9:35 pm ]
Post subject:  Re: Exhaust Manifold New or Used
Quote:
Not that I need one, but I have found it odd that no one services the spring / damper for the exhaust manifold.
It was available as a repair part for many years, but these are antique engines now. It's 33 years since the last Slant-6 engine was installed as original equipment in a new vehicle. It's half a century since the last Slant-6 engine with the pre-'71 type heat riser was installed as original equipment in a new vehicle. Heat riser parts are on the long list of parts that are no longer readily available.
Quote:
Certainly that system was not unique to Chrysler?
No, most engines had heat risers…and none of the parts are universal or standardised. The springs we're talking about here were specific to the Slant-6.
Quote:
Or are none of the manifolds serviced with replacement springs and baffles?
A new manifold comes complete with fully-assembled heat riser valve.
Author:  DadTruck [ Fri May 01, 2020 10:46 pm ]
Post subject:  Re: Exhaust Manifold New or Used
To use a stock style exhaust manifold without a functioning spring, but with a damper that moved one could fashion a manual control, something similar to a manual choke control that would allow one to open the damper on a cold motor then close it as the engine warms,,,probably easier written than done, but certainly with in the realm of being possible.
Another option would be to adapt an electric motor from an exhaust cut out to the baffle shaft. Then you can open or close the baffle with the flip of a switch. A quick search on google provided replacement electric cut out motors for $20.00
Author:  Rodrju [ Sun May 03, 2020 9:51 pm ]
Post subject:  Re: Exhaust Manifold New or Used
Quote:
these are antique engines now. It's 33 years since the last Slant-6 engine was installed as original equipment in a new vehicle. It's half a century since the last Slant-6 engine with the pre-'71 type heat riser was installed as original equipment in a new vehicle. Heat riser parts are on the long list of parts that are no longer readily available.
I have to remind myself of this all the time because I take for granted how many parts are still available.

While its disappointing, I have to remember that expecting some obscure spring last used in 1971 may not be realistic.

These cars are old.

This is pure opinion...

I believe that the since these motors we installed in such a wide variety of machines...cars, trucks, boats, industrial equipment, coupled with there renowned durability, they have remained in service well past the normal time period.

Typically, trucks/vans stay in use longer than cars. The fact the Chrysler was still installing it relatively unchanged in trucks/vans into the late 1980s, has also served to keep aftermarket items often times in stock. Its rare, but even here in the rust belt you still see the occasional D150 with the buzz of the 6...

Some parts still exist, because some market still exists.

For how long..? We'll see.
Author:  Reed [ Mon May 04, 2020 1:54 am ]
Post subject:  Re: Exhaust Manifold New or Used
To be perfectly honest, the disappearance of parts like the heat riser service kit is part of my motivation to migrate to a modern MPFI system. With MPFI the intake becomes a dry manifold and intake heat is no longer needed. I can switch to headers or true Dutra Duals and suffer no downside.

As more parts become no longer available, it will be time to retire these old beasts or get creative about adapting other parts to them. I find adapting parts a fun challenge, but the more you bodge it together, the less pratical it becomes as a daily driver.
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