I thought I had the perfect set up with two Dutra duals, but no. The bolts that hold the exhaust manifold on are barely reachable with the Dutra duals, at least the castings I have, and the bolt for cylinder number six was impossible to get a socket wrench on. I made a special open end wrench with a bend in it to reach up under the manifold and tighten it up. Well, you could not put much torque on it, and it it worked loose and started a leak there. Re-tightening it helped but did not completely eliminate the leak. It is very annoying. I hate the thought of taking the manifolds off and replacing the gasket only to have this happen again. So here are the questions:

1. Are headers better or worse? Would I be jumping from the frying pan into the fire here?
2. Does anybody make a pair of 6 into 2 headers similar to what my current Dutra set-up does?
3. Does anybody make any kind of headers these days for a slant?
3.Does anybody have any ideas about how to make a better tool to get to these bolts?
4. ARe there better exhaust/intake gaskets than the Felpro gasket that came in the rebuild kit? If so, where do I get them?

The car sounds cool at speeds below 2k rpm but up around 2500 really starts to drone. I can hardly hear my cell phone ring. Maybe that is a good thing, but am kind of unhappy with the exhaust in general. Is it time to rethink the entire thing? Lou has teased me for years for not having just a single exhaust and wearing my /6 identity more proudly. However, I know from experience that even a good muffler will drone above 2200prm on a slant with a single large exhaust pipe.

If I can get this set up to be quieter with better mufflers, and get the Dutra duals tight enough to seal, that is the route I am inclined to take. Thoughts? As always, thanks.

Sam

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you can get new Hooker super comp headers (two piece) from amazon for $494.95

http://www.amazon.com/Hooker-5602HKR-Su ... automotive

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I can only answer #4, as I don't have DUTRA Duals.(yet!) http://catalog.remflex.com/MOPAR_Header ... p/6008.htm

and swivel(s) and short extensions don't work for tightening?

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1964 Dart GT

The rear manifold on a Dual Dutra manifolds set-up Dual Dutra Duals) has a couple of bolts that are hard to access...

I use a 1/4 drive socket and a special end wrench to tighten the set I use.
One other thing I did is marked the area were the clearance is limited and did some grinding on the rear manifold, to improve access. (yes, I had to pull-off the rear manifold to grind on it)
DD

Doc's got it.

This is just common sense even with the 70's stock manifolds (which the casting bump under the intake manifold makes it hard to get direct access to the inner #4 bolt even with the 1/4" extension. Since this is a somewhat custom installation for our application it really is imperative to mock up the set to the engine and check for issues, then use a combination of grinding tools to make life easier later. I did this last year on my hpak duster and installed the dual duals and a hyper pak, I mocked them up without the intake, made some mods so they would bolt up easier, then mocked up the full set, and marked with a magic marker and did some more grinding. As it sits now, I didn't have any access issues to any of the bolts and it was the easiest installation of a slant six set I had ever done.

-D.Idiot

A 1/4" drive swivel and various lengths extension work well. They are very narrow and compact. I don't mean a swivel + socket - I mean the sockets with built in swivel like these. Like Doc said, may have to grind a bit of the runners around the ears to allow for room to get the socket on.

Sam did you remember to grind down the chunk of material that extends from the block towards the rear? If you don't the rear dutra manifold may not sit fully flush with the head causing a leak. This pic from Doug's site illustrates what I"m talking about.

If this grinding is necessary every time, why not sell them with the mod already made?

I have the hooker super comps, never mounted them up or anything yet. each tube is 1 5/8" and it's a pair of 3-1's. I believe the collector is 2 1/2 (iirc). They are long tubes as well. I'm not sure if that affect a-bodies or not.

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1965 Plymouth Belvedere II Turbo Project - SOLD
2002 Subaru OBS
1995 Lexus LS400 Race Car

All great tips. Thanks to all, and folks with great creds. I will plan on taking it all apart some day and putting it all back together with more care towards this issue. One of the problems is that I assembled this entire engine out of the car, and then dropped it in assembled. Things were much easier to get to out of the car.

Another thought entered my mind. There was a period of time about 3 years ago when this car was at a so-called tuner's shop, supposedly getting dyno tuned. He charged me $800 for "supposedly" replacing the intake gasket. I had no way of knowing if he really did so, but kind of always assumed he did not, but was simply justifying his high fee. Now it occurs to me maybe he did replace the gasket and it was his fault the bolt was loose.

How many out there have a pair of Dutra Duals that are completely leak free? Pierre, Thanks for the link to the photo. I do not remember if I ground down that boss on the block. It has been maybe 7 years now. I will certainly check on that. I can likely check that out with a feeler gauge while on the car. I think there is much room for improvement.

Mr Zeal, the answer to your question is that these manifold castings were a labor of love on Doug's part. We were delighted to have SOMETHING to work with as a good start. As hobbyist it is kind of expected we must do our custom thing to make after market parts of any kind work, but especially if your thing is slant sixes, which has little or no support from the market place. Heck if you look at Summit's catalogue, there is darn little V-8 Mopar support there compared to the GM and Ford stuff. So slanters get to practice the personal growth habit of gratitude when any special thing shows up.

One more question again: are headers historically harder to keep leak free than these cast iron manifolds if they are done right? And do headers offer any economy advantages over the Dutras? I am not interested in racing, but do care about economy. $500 is more than I care to spend now for headers if there is no real advantage to me. I do not need the carb heat feature of the stock manifold as this engine has EFI which works fine without it. Thanks again.

Sam

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I assume headers would improve mileage, the engine flows more efficiently with them. Someone with more knowledge towards building a car for economy would have proper information on that.

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1965 Plymouth Belvedere II Turbo Project - SOLD
2002 Subaru OBS
1995 Lexus LS400 Race Car

I think it is grinding the block, not the manifold.

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1964 Dart GT

Sam

I have a set of Dutra Duals on the 83 D150,,

straight edged the manifold to head flanges, they were pretty good, did the same on the Dutra outlets to exhaust pipe flanges, the Dutras were flat only in a very small diameter around the outlet. Note: I had the intake / exhaust surface on the cylinder head cut just enough, like .010, to true it up when the cylinder head firing deck side was cut.

I went ahead and installed the Dutras, used thin after market 2.5 inch diameter gaskets on the flanges,, one blew out in the first 50 miles.

I replaced the thin after market gaskets with Remflex gaskets, and they have been fine.

If I ever get to the point that I remove the Dutras or buy a second set, I'll have the mounting flanges checked and milled flat if needed.
Note: I also checked the exhaust pipe flanges, they were not top shelf either..so I'll also pay more attention to those.

I remember needing to do some misc light grinding on the Dutras to allow for socket clearance,, nothing major..

After the prefit work,
I had them ceramic powder coated,, I went with the Dutras wanting a cast manifold for long term / high usage durability.

Sam, I have the Clifford shorty headers, but they are a pair of 3 into 1 designs. I have been pleased with them so far, but it is a must to use a top shelf manifold gasket like the Remflex that has been mentioned. The biggest downside to using headers is the greater amount of radiant heat they release, compared to cast iron. Underhood temps will be greater using headers vs. cast iron ones. For the exhaust noise, I would recommend using a muffler that has two inlets and one outlet connection. The longer the muffler case, the quieter they usually are. Stay away from a "flow-through" muffler, and get one with chambers in it, if possible.

Good luck,

Brian

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Flyin' Brian

74 Duster, 225, rear-mounted blow through turbo at 12psi boost, street/strip car
"Sixy Beast"

Could not fit a .010 feeler gauge between head boss and exhaust manifold flange, so suspect this is a cause of problems. I hate to tear it down just as cruise season is arriving. I wonder if this is more than a 1 day job? I guess if I collect all the gaskets ahead of time maybe I can do it in one session. However some grinding will be needed to get wrenches where they are needed this time.

Sam

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Sam, You will not want to deal with long tube headers. Shorty's maybe so. But there is no reason that you should not be able to get a great seal on the Dutras. One thing to check is that your intake and exhaust manifolds are the same height where the washers go on. Mine were off some and I bent some of the triangle washers so they hit the manifold more evenly.

If you are in a hurry, I have a Remflex on the shelf. Just replace it when you get time.

Rick

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6