Magnum Exh manifold machining.

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Unless these are somehow special, you can buy a pair of new aftermarket (Dorman, etc...) ones for around $200-$250.
 
I have an idea what might work. Thinking about the flattening jigs woodworkers use for getting a table top or other surface flat using a hand router. Basically they build a movable gantry/carriage in which the router sits, then they simply place it over the work piece and pass the router over a billion times and end up with something that matches the plane of the carriage.

I could mount a 4" grinder onto a carriage like that and as long as everything is locked into place, just keep sliding the grinder back and fourth until the material is removed. Like a hillbilly surface grinder.

-=C
 
Unless these are somehow special, you can buy a pair of new aftermarket (Dorman, etc...) ones for around $200-$250.

They have the 2-1/8" outlets so in a way, they are "special". Using them for a magnum into a 65 valiant swap. Everything I've read where people have done it, they "wish" they;'d taken more off than say 3/16. That's where the 1/4" comes from.
 
I think there are parts of the head, or even the block, that may interfere if you take 0.250" off those flanges. I know I had to grind a little on my LH head for clearance, and I'll bet we only took .020" off my manifolds.


That's good to know, I'll check before I get too crazy
 
I have an idea what might work. Thinking about the flattening jigs woodworkers use for getting a table top or other surface flat using a hand router. Basically they build a movable gantry/carriage in which the router sits, then they simply place it over the work piece and pass the router over a billion times and end up with something that matches the plane of the carriage.

I could mount a 4" grinder onto a carriage like that and as long as everything is locked into place, just keep sliding the grinder back and fourth until the material is removed. Like a hillbilly surface grinder.

-=C
Stranger things have been done, it could work. You should be able to hog most of the material by hand and use the fixture for the last bit, but it will take some time and you'll have to nibble at it. I've seen guys grind hardened lathe ways by mounting a grinder on a sled and running it up and down the less worn tailstock ways. Those jobs ended up at a couple tenths of thousandths over several feet.
 
Stranger things have been done, it could work. You should be able to hog most of the material by hand and use the fixture for the last bit, but it will take some time and you'll have to nibble at it. I've seen guys grind hardened lathe ways by mounting a grinder on a sled and running it up and down the less worn tailstock ways. Those jobs ended up at a couple tenths of thousandths over several feet.

Sort of my thinking as well. Should be "good enough"...
 
Seems trying to find someone to shave some material off the face of an exhaust manifold requires a secret handshake and a decoder ring. Is it really that difficult? Anyone know a shop in San Antonio that can do it? I've already called Duffin, no go.
Parks engine service. Seguin, Tx
830-379-4562
They have resurfaced exhaust manifolds for me before.
 
No problem. That is where I get all my machine work done. Been going there since the mid 90's.
 
My son James is working on his first Mopar and needed some manifolds. I happened to have a pair in the shop. The left side was machined because it was so close to the steering column. The thing is, you can’t take too much off because of the center bolt hole mounting flanges. They’re only 7/16” thick. We ended up taking .150” off.
 
My son James is working on his first Mopar and needed some manifolds. I happened to have a pair in the shop. The left side was machined because it was so close to the steering column. The thing is, you can’t take too much off because of the center bolt hole mounting flanges. They’re only 7/16” thick. We ended up taking .150” off.

265275DF-72C4-454F-8945-76E8DE5BF466.jpeg
 
My son James is working on his first Mopar and needed some manifolds. I happened to have a pair in the shop. The left side was machined because it was so close to the steering column. The thing is, you can’t take too much off because of the center bolt hole mounting flanges. They’re only 7/16” thick. We ended up taking .150” off.

Yup, my estimate above of how much I need to remove was way off. Probably more like .180 to .200
 
How much room did you have with .150 removed?

This is in his 69 Dart, 318 with manual steering. Since the pic was taken, he made a small aluminum heat shield. So far so good. He might do the lower bearing upgrade later on. NOTE: before the machining, the corners of the steering coupler were just barely touching the manifold. Not any more.

46810D22-5B42-4F5D-938C-5ACB0D49AF13.jpeg
 
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