The inductive coupling falls off with the square of the distance, which means that a little bit goes a long ways - double the separation and reduce the inductance by 4, triple it and reduce it by 9.

As others who know way more about cars than me have said, a quality wire should not have problems.

That looks very good!

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Not close enough to cause inductive misfire, they won't be. They really have to be parallel and right next to each other and taking the same curves for more than an inch or two. Of course, that's with good wires. With poorly-chosen wires (or wires in bad shape), all kinds of faults are possible.
Tommy was wrong, both in his comment and in his explanation for it. The Slant-6 intake was revolutionary in that its six runners were much closer to equal in length, and thus it vastly improved cylinder-to-cylinder evenness of fuel/air mixture distribution, compared to the log/rake type intakes used on all other inline sixes. Of course it's nowhere near as good as a modern port fuel injection system, but evenness of cylinder feeding was a slant-6 strong point, not a weak point. Tommy simply didn't know what he was talking about.
True, but engine balance and air/fuel distribution evenness are wholly separate matters. No reconciliation required.
The slant-6 intake design is not flawed, except for the limitations inherent in any wet-manifold intake tract (carbureted or throttle body injected). Nor is the head design flawed, though it is "smaller" than desired for maximum horsepower, and its combustion chamber shape is not as refined as it could be.
I'm not seeing any mention of what spark plug wires you're running. That's going to be much more important than how they're routed. Coil-on-plug is nifty, but don't fool yourself into thinking you're going to solve a (nonexistent) "flaw" by going to the trouble and expense of putting together a coil-on-plug system (or by going to extreme lengths to devise novel spark plug wire routing). Slant-6 engines in proper repair with bone-stock, low-spec parts were idling smooth as glass even back in the bad old days when pathetic ignition systems, crappy gasoline, and a whole bunch of other factors were working against a smooth idle.

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

If I had to do it again, I would have shortened #1, #5 and #6 just a bit so they didn't touch the inner fender, but otherwise it's fine.

The kit has lots of extra hardware, so I still could shorten them a bit.

brian

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https://tinyurl.com/yynpj4v2

Spark plug wires are standard NAPA stock. I put those on several years ago in an attempt to cure High voltage interference with EFI pick up, thinking solid core wries might be the culprit. This happened only under boost when ecu would suddenly double rpm read. It did not fix it. Removing turbo did. I will put new, better wires on as soon as I sort out what style and length. I really liked the look of Brian's wires.

It was probably a poor choice of words to say the slant was "flawed". I love it. It would have been more appropriate to say there are those who can and have compiled a lengthy wish list of "upgrades" to our beloved slant, some of which are really pie in the sky, and would cost rediculous amounts of money. My focus is not on such radical mechanical changes, no matter how "advanced" these would be, or how much HP would be added.

There certainly have been advances made in in-line six refinement since the Mopar slant was introduced. Those advances include increased cost, complexity, higher maintenance costs, and possibly reduced durability under certain circumstances, (overheating for instance). My BMW 2.8 slant six is smooth as silk, has about 240hp, gets excellent gas mileage for what it is, and you can hardly tell it is running to watch it idle. Is it fair to compare it to the Mopar Slant? No! The BMW has twice as many valves and cams and many maintenace items that cannot be accessed without removing the intake manifold. Do I want the Mopar slant to BE a BMW slant? No. I have been told if the Bimmer slant overheats, the head is toast. You cannot beat the Mopar slant for ruggedness.

But there are those on this forum talking about producing a Mopar Slant head that would copy the cross flow design of the BMW hemi head design. Dan, I think you addressed my question nicely when you said proper ignition components in good condition can make the slant work fine.

So here is my question for you? Do you think it is possible to make a Mopar slant as smooth and polite as the BMW's? This is not a rhetorical question. Owning the BMW has changed my focus with the Dart. Without spending an inordinate amount of time and money, I am investigating ways to make my slant smooth and quiet. This challenge is as compelling to me as going fast is to the race guys. Any advice along those lines, and there has been some offered already, is appreciated.

Sam

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Eliminating the wet manifold and going to either batch fired or sequential fuel injection would help smooth out the idle, improve emissions, and improve performance and economy. I think rough idle is due to variations in valve lash, the inherent fuel distribution problems of any wet intake manifold, and wear on the internal components. That being said, I am usually able to get any slant I drive to idle very smooth.

Making it quieter is easy- electric fans or a clutch fan, hydraulic cam and lifters, exhaust work.

Rather than focus on a new cylinder head, I would love to see a concerted effort to produce a fuel injection kit that would include a fuel rail and an intake manifold with injector bosses already present. My preference would be to make it with provisions to mount a stock 5.0 mustang throttle body and still have a working EGR system.

Any effort to make even a small run of standardized port fuel injection manifolds and fuel rails would be worthwhile.

In my mind, and more so given the rapidly dwindling supply of decent carburetors, the next real push in the slant six world should be creating some universal parts to allow the adaptation of modern fuel and ignition management systems to the slant. I am talking true MPFI systems with all emissions controls in place and computer controlled timing. In other words, an EEC-IV based MAF MPFI system adapted from the late 80s and early 90s Ford vehicles.

As an aside, my 89 Ford van has exactly such a system, and it has VERY long stock spark plug wires draped all over the engine and I don't think I have a misfire problem.

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Casually looking for a Clifford hyperpak intake for cheap.

Brian, that looks beautiful. Do you have radio interference from them? Do you know by chance how long you cut the various leads? Thanks.

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Oh, heavens. That's carbon string. Pretty minimal at best. Put some good wires on there (I'd point back at Magnecor or Aurora) and you might well see a variety of niggling/marginal issues vanish.
Quite so. Solid-core wires have no home or business on a vehicle, unless they're equipped with lump resistors.
Me too! Very clean setup.
Sure, but there are also those talking about winning the lottery. Twice. And then getting hit by lightning. Twice.
I think you can probably get reasonably close.

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

They say a persons reach should exceed his grasp, and that a target should be beyond easy reach. Whatever that means, my goal is now to work towards refining the slant, and not simply power. Maybe BMW smooth is a reach, but is a worthy goal. Once I get the wire length determined, I will order a set from Aurora.

Brian, you could route number six and number one up and over to clear the fender. Hang it from a hanger made to bolt to the valve cover hold down, with an insulated loom of some kind. With your beautiful work, I am sure you would make it look wonderful.

There are lots of little things BMW did to refine it, which are not difficult, or beyond reach. One example is they put shielded wire on all the sensor grounds. This is a cheap project money wise, but if they did it, you can bet it was for a reason. That is another project I will take on.

Sam

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