hello. this is my first post.


what are the advantages/disadvantages of headers/split manifold? id also like to get as much input as i can on loseing the heat exchange with headers. im not after a hot rod. im after the shock factor.

In general: Headers = noise, leaks, rust, poor fit, heat-related running problems (not enough heat *and* too much heat in the engine bay).

Split (DutraDual) exhaust manifolds: No leaks, good fit, no heat-related problems, novelty visual effect.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

One word: Zoomies!

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"When you find a big kettle of crazy, it's best not to stir it." - Pointy-haired Boss

1964 Valiant V200, 225/Pushbutton 904
BBD, CAI, HEI, LBP, AC, AM/FM/USB, EIEIO

You can get the split manifolds from Doug Dutra, otherwise known as Doctor Dodge. They will require that you fabricate some custom pipes, but are worth the effort if for no other reason then you can tighten the manifold bolts up tighter without fear of expansion cracking the exhaust manifold. The factory system is so long that they must leave the entire intake/exhaust gang a little on the loose side(10 ft/lbs of torque), so that they can slide a little as they expand. Once they are expanded everything gets tight, but I always suspected vacuum leaks when a slant is cold make a cold start problem worse. Once you can really crank down on those manifld bolts, which you can do with the split manifolds since they are less than half as long, she drives better when cold.

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Hello,
Man, you got two really knowledgeable and helpful guys to answer right off Dand and Sam) and a third (me) who is learning at their knees! If you PM me with your regular email, I will send you a good pic of what a set of Dutras looks like on my newly finished slant with offenhauser 4bbl intake and edlebrock 500cfm carb. Chrome, stainless, new paint = shock for sure!
rock
'64d100

Paint the car pink.

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I've been calling it as i see it for my entire life and that's not about to change. Take it or leave it.

thanks for all the info.


I like the DD1 thats on it now. not high impact but "normal". i dont wanna shock them with how it looks on the outside. i wanna shock them with how it looks on the inside.

I had Doug Dutra have a pair ceramic chrome plated and they are SHARP AS A TACK! Then I used 2.25" dual exhausts, front to rear, with Turbo mufflers. They are a little loud for the timid, but music to my old 62 year old ears. The sound at full throttle is like nothing else I've heard, and believe me they sound tough. This is a little more expensive, especially with the chrome-like ceramic coating, but I only wanted to do this once, and to get it right the first time. It IS right. Best of luck to you on your exhausts.

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Restored '62 Signet, 229 4bl, Offy intake, auto, Dual Dutra exhausts, shaved head and block, high stall converter, 1.6 roller rockers, etc.

Yes, you have a nice pair of manifolds.
DD

Don't you still have to worry about the intake manifold cracking though, since it still spans the full length? If not, what do you consider "really crank down?"

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Used to own:
'82 Dodge D150
Erson 270 Cam, O/S valves, mild port work, ~9.5:1 compression

Currently fighting with an '85 VW Cabriolet

My other passion

Since no-one else answered, I'll venture a guess that the intake manifold will expand much less than the exhaust. No idea what number of foot pounds would qualify as "really crank down",
but surely "a bunch" more than TEN!!!

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'64 Dart GT convertible, 64 Dart 170 2-door post sedan in faded blue and rust (the Az Dart) & a sixty THREE Dart 170 2-door post sedan in faded blue and rust. (future project)
Early Dart Disorder (EDD) is real, and I've got it!

The intake manifolds do not crack like the exhausts—ever. Sometimes an intake will develop cracks in the "floor" area below the carb due to the thermal cycling caused by the exhaust hot spot, but no, you do not need to worry about stress cracking due to the intake spanning the whole length of the engine.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Well, surely. Vacuum leaks on any engine will cause problems with starting, running and driveability. There are no such leaks when the slant-6 manifolds are in good shape and are installed per factory specifications, using a quality gasket.
This advice is not at all sound. "really cranking down" on the manifold "bolts" (which don't exist; they're studs and nuts) is a collossally bad idea. Don't do it. Flat manifold and head surfaces - a quality gasket - and factory installation procedure and torque values. That's the recipe for a successful and leak-free manifold installation. If your car has cold starting/cold running problems, they are usually not because of insufficient manifold stud nut torque, but because of carburetor and/or choke issues. Find and fix the problem, don't hamfist the manifold stud nuts, because if you do, you will usually come to regret it one way or another.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Impact wrench not really

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir