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Dutra Duals Question
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Author:  scraigallen [ Wed May 03, 2023 6:12 am ]
Post subject:  Dutra Duals Question
Starting a new slant six build and had questions about best exhaust for my application. I want to build a good running street engine for my 1984 Dodge D150.

Regarding exhaust, my favorite exhaust manifold option are the Dutra Duals. Question is: when you do both duals and lose the intake manifold heating, does that cause any cold starting or drivability issues?

I would like to do both front and rear duals, but I would consider doing just the front dual and modifying my old manifold to keep the intake manifold heating, if that is worth it.

I live in Wilmington, NC, so not a cold climate. Regarding intake and carb - thinking a Weber 38/38 with Aussiespeed mid or long 2 barrel intake. Motor is mostly stock with .040 pistons.

Thanks for your input! I have searched the forum, but keep running around in circles with all of the different things to consider.

Craig
Author:  Greg Ondayko [ Wed May 03, 2023 8:02 am ]
Post subject:  Re: Dutra Duals Question
Yes it does if you are keeping a carb. A water heating device can be attached to the bottom of the stock manifold to solve this problem.

Port EFI also solves this issue but is much more work and expen$e to accomplish

Cheers! Greg
Author:  slantzilla [ Wed May 03, 2023 9:25 am ]
Post subject:  Re: Dutra Duals Question
The original DD's had a modified stock manifold for the rear.
Author:  Greg Ondayko [ Wed May 03, 2023 9:40 am ]
Post subject:  Re: Dutra Duals Question
Yes and I think the OP knows that, He was also asking about Dual Dutra Duals.

You 'da man big D!
Greg
Author:  scraigallen [ Wed May 03, 2023 12:06 pm ]
Post subject:  Re: Dutra Duals Question
So since I want to stay with a carb, maybe it's best to do the original Dutra Duals with the modified rear manifold.

I have a couple of old manifolds, the exhaust flaps seem like they have seen better days. Can the exhaust flaps be restored or replaced?
Author:  CNC-Dude [ Thu May 04, 2023 2:57 pm ]
Post subject:  Re: Dutra Duals Question
On other inline engines that use Offy or Clifford intakes, there is a method to make them heated by using a water manifold and attaching it to the underside of those intakes. Does the Aussiespeed intakes have provisions for this type of modification? If so, then you won't have to be concerned with using a modified rear exhaust manifold if you dont want to.
Author:  kesteb [ Thu May 04, 2023 4:07 pm ]
Post subject:  Re: Dutra Duals Question
Yes, they sell a box that can be attached to the manifold.
Author:  DadTruck [ Thu May 04, 2023 7:18 pm ]
Post subject:  Re: Dutra Duals Question
For the slant in the 83 D150 that has dual Dutra’s, I modified the egr cavity under the carb to make it a hot water hot spot.
Basically I plugged the through hole into the intake plenum, made a plate for the bottom side with a fitting for engine hot coolant in and a plate for the side where the egr valve normally resides with a fitting for hot engine coolant out. Made the plates out of 3/8 in thick steel so they could be threaded to accept the fittings.
Made gaskets out of reinforced paper gasket material with a little RTV applied. Used the stock three bolts for the bottom plate and two bolts for the side plate. It has worked fine for 10+ years and nearly 50K miles.
Author:  GTS225 [ Fri May 05, 2023 6:25 am ]
Post subject:  Re: Dutra Duals Question
Quote:
For the slant in the 83 D150 that has dual Dutra’s, I modified the egr cavity under the carb to make it a hot water hot spot.
Basically I plugged the through hole into the intake plenum, made a plate for the bottom side with a fitting for engine hot coolant in and a plate for the side where the egr valve normally resides with a fitting for hot engine coolant out. Made the plates out of 3/8 in thick steel so they could be threaded to accept the fittings.
Made gaskets out of reinforced paper gasket material with a little RTV applied. Used the stock three bolts for the bottom plate and two bolts for the side plate. It has worked fine for 10+ years and nearly 50K miles.
NICE! I approve. 8) :D (Not that it means a whole lot.)
Gotta like ingenious uses of what one already has available.

Roger
Author:  akbmotorsports [ Fri May 05, 2023 11:10 am ]
Post subject:  Re: Dutra Duals Question
don't know if they are still available, but just fyi the hooker headers have a small tube coming of one of the runners that connects to a plate that attaches to the intake for heat.
Author:  hyper_pak [ Thu May 11, 2023 11:26 am ]
Post subject:  Re: Dutra Duals Question
Yes they did, it looks like this:

Attachments:
Hooker Heat Plate s.jpeg
Hooker Heat Plate s.jpeg [ 47.51 KiB | Viewed 1676 times ]
Author:  Jase [ Thu May 11, 2023 11:48 am ]
Post subject:  Re: Dutra Duals Question
Quote:
don't know if they are still available, but just fyi the hooker headers have a small tube coming of one of the runners that connects to a plate that attaches to the intake for heat.
Is there actual exhaust flowing through that? I can't imagine how that actually warms up the intake if it is just a dead end tube.. Can someone explain how the Hooker intake heat system works, for those of us who have never seen such a thing?
Author:  hyper_pak [ Thu May 11, 2023 12:12 pm ]
Post subject:  Re: Dutra Duals Question
On the Hookers I had on my Barracuda it was just a companion flange like the one shown but on one tube.
I don't remember which but it was close to the center.
There was no hole in the header or in this plate either.
I guess the theory was as the air heated due to exhaust gasses it would rise and warm the underside of the intake.
I never used it as I had it in a race (street) engine and never ran it in cold weather.
And the Hyper Pak I had didn't have a provision for it anyway.

Interesting story,
one of the Chrysler engineers drove one of the Hyper Pak Valiants back from Daytona.
Somewhere up north the car was driving poorly.
He pulled over to find the bottom of the intake packed in a block of ice splashed up from the road.
I think they chipped it off and waited for the exhaust to melt it a little before continuing on their way.
I need to go find that source again.
Author:  Rick Covalt [ Thu May 11, 2023 4:33 pm ]
Post subject:  Re: Dutra Duals Question
If you are worried about having heat under the carb, then you know your answer. Modified stock manifiold. But as was mentioned in your other thread you are not in a really "cold" area. Others in much worse climates run all year without manifold heat and headers. Myself included.
Author:  hyper_pak [ Fri May 12, 2023 7:43 am ]
Post subject:  Re: Dutra Duals Question
Quote:
On the Hookers I had on my Barracuda it was just a companion flange like the one shown but on one tube.
I don't remember which but it was close to the center.
There was no hole in the header or in this plate either.
I guess the theory was as the air heated due to exhaust gasses it would rise and warm the underside of the intake.
I never used it as I had it in a race (street) engine and never ran it in cold weather.
And the Hyper Pak I had didn't have a provision for it anyway.

Interesting story,
one of the Chrysler engineers drove one of the Hyper Pak Valiants back from Daytona.
Somewhere up north the car was driving poorly.
He pulled over to find the bottom of the intake packed in a block of ice splashed up from the road.
I think they chipped it off and waited for the exhaust to melt it a little before continuing on their way.
I need to go find that source again.
CORRECTION: There is a hole in the bottom manifold plate! But not the header.
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