Replacing exhaust manifold (Building a header)

[isaac_alaska]

hey, that's good to know. i hadn't thought of that. it's probably better if they all sweep into a single collector with gradual and smooth bends, rather than a sharp impact like i have now, to keep from burning through the side of the tubing? I'll play around today and see what i can come up with!

[isaac_alaska]

just two bolts left i think. one of them is the lower exhaust manifold bolts, actually one was stripped out already, and i have to try to get the nut off the other one and then get both studs out to replace them. and then i have to figure out how to get the very bottom center bolt out. i think it's probably easiest from underneath and i just can't see it yet

[isaac_alaska]

If/when I get the rest of the nuts off the studs, assuming the two long studs stay threaded in the block, how do I go about getting the manifold off the studs? It looks like the manifold and studs are going to be siezed together and require prying the manifold off, but I want to be very sure I don't damage the block. The manifold is so full of cracks I'm not too worried about hurting it.

[w30bob]

Isaac,

A few decent whacks with a rubber mallet on the manifolds should free them from any hold corroded studs have on them. Prying on cast iron (i.e., the block) always makes me cringe.

later,
bob

[isaac_alaska]

thanks bob, that was my feelings as well. I'll have at it with a rubber hammer later, i think i'll leave them soaking in oil for one more day and attack it tomorrow if the snow lets up a bit

[isaac_alaska]

got the manifold off, i had to drill out the two long studs before i could even get the manifold off, they were VERY well seized into the casting. drilled them down till there was just an inch or so left and then i was able to work the manifold off witha couple of big screwdrivers using them as wedges, as well as a pair of heavy duty ratchet straps to put a little pull on it. Now i've got a new flange all cut out, just trying to figure out how i want to piece the headers together.

[isaac_alaska]

anyone have an opinion on the "ideal" exhaust tube configuration? at this point i'm thinking just two pairs of three, so cylinder 1, 2, 3, and then 4, 5, 6, and then bring both of those together in a Y. this seems like the easiest config...but in an ideal world is this what we want? starting from total scratch has the benefit of being able to do about anything i can imagine

[w30bob]

Hi Isaac,

I think when you read all the info you can find regarding straight 6 headers the general consensus will be there is no consensus. Most often the answer is "build a few sets and test them on the dyno to see what works best". In theory what should work best is 6-2 with true dual exhaust. Each group of 3 pipes should be 120 degrees out from each other. I don't remember the firing order of the 230 off-hand, but that may in practice be a bit tricky to weld up. I remember that Clifford used to have some good info on their header design available, but I don't know if they're even still in business.

regards,
bob

[06boblee]

Google "Dodge flat head 6 headers", there are a lot of pics of headers and manifolds.

[isaac_alaska]

maybe something more like this?

[T. Highway]

That looks nice.

Bert

[isaac_alaska]

Thanks! Designed in solidworks, now I'm waiting for tubing

[isaac_alaska]

It's been a while, I didn't want to post pics till i had a good idea of what i was doing and if it was going to work. Well, looks like it's going to work, it's certainly more work and more time than i expected it would take, but what project isn't? Last time, i was waiting on tubing. I ordered all the tubing from Columbia River Mandrel Bending (here). I ordered most of the tubing in 180* bends, because you get the most bend/$ that way. I also ordered a one stick each of straight 1.5, 1.75, and 2". It's only mild steel, because i figured it would be easier to work with and cheaper to buy initially. If i had known how much work would be involved i probably would have gone stainless from the start, if I build another one it will be stainless, because this isn't something you want to rust out after a few years.

Here are a few pics of what showed up in the box.

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I initially cut each of the U shape pieces in half on the band saw as near to the center as i could get, and then surfaced them all to the same height on the mill with a carbide end mill.

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I guess i can only add three attachments at a time so that will have to be it for this post!

[RMS]

looking good Isaak! that is one a nice thick flange. In an ideal world all the runners should be the same length....but more importantly on the m37 is will it hang up? will the diff and drive shaft clear and can the pipe be directed smoothly under the rear motor mount and cross under the frame directly behind the front passenger side shackle?

[isaac_alaska]

I've test fit what i've got done a few times, and i'm pretty sure it will fit. i'll be fabricating the rest of the exhaust pipe as well so i'm pretty sure i can route it where it needs to go to stay out of the way. If anyone has a line on a cad model of the engine i would be super interested in it, it would make it very easy to do some complex fitment work without having to go out in the cold!

Here's a couple pics of how i marked and cut the pieces, using the CAD file to create a 3d template, printed the templates from PLA plastic, and then cut the pieces and angles on a band saw.

They may not look like much laying there

IMG_2528.JPG (113.76 KiB) Viewed 2535 times

but when you clamp them onto the pipe, all you have to do is trace around them with a marker and you have a perfect cutting line. no more "cut, test, cut, test, grind, fit, grind" it's just cut once and the pieces fit perfectly

IMG_2527.JPG (87.06 KiB) Viewed 2535 times

using a movable vice to hold the leg vertical during the cut, ensures that the saw blade will follow the line on the bottom as long as you are careful to follow the line along the top.

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