Exhaust manifold skim

[Guineafowl]

Td5 exhaust manifold.

Not sure about the setup or the flycutter, but it seems to have taken the warp out. Took AGES to set up. I’ll probably take out the machining marks with some sandpaper on a flat surface

It’s a half decent boring head, with a cheap brazed carbide cutter running backwards. With a cut radius of about 65mm, what rpm would you use? I went for 150. Feed was by hand, so nice and slow.

 

[Barking Mat]

Fair play mate, was it warped ?

 

[Kayos]

Fair play mate, was it warped ?

They always warp

Took mine to a shop that did them all the time, he had a jig to set them up

 

[Pete.]

Good job!

Did mine with a big fekkin file.

 

[minimutly]

Did one a couple of yrs ago, pain in the but to set up, if doing more than one I would make a jig too...

 

[Moose McAlpine]

Something else to add to the list and look forward to when i get around to my Disco 2..

 

[Guineafowl]

Fair play mate, was it warped ?

It wasn’t blowing, but I took it off to replace the threaded coolant plug behind it. Checked flatness and it was bowed outwards from the middle by 40 thou or so.

 

[8ob]

You cant beat a planitor head grinder for jobs like this, no set up time. Something like that manifold would take a few minutes, just wipe the manifold over the table a few times.

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[Trevorleach]

That manifold wants dewebbing.

 

[Kayos]

That manifold wants dewebbing.

Engineering shop advised against that, said they often warp again and worse

I had mine skimmed, new turbo and did 30k without issue, not dewebbed

 

[8ob]

Cast iron is a strange material, on the move for quite a long time when new which is why performance engine shops in the states turn engine castings out in the elements for about eighteen months prior to any machine processes. I think a used cast iron manifold that has had a skim is more stable than a new one.

Bob

 

[Guineafowl]

Cast iron is a strange material, on the move for quite a long time when new which is why performance engine shops in the states turn engine castings out in the elements for about eighteen months prior to any machine processes. I think a used cast iron manifold that has had a skim is more stable than a new one.

Bob

My thoughts exactly. If it ain’t broke (well, it was slightly ‘broke’, but not blowing).

To my mind the cast is now ‘seasoned’, but by changing the structure it will want to move again to a new set point.

If I’m wrong, I’ll be back on here cussing about having to set the c**ting thing up on the mill again.

 

[Pete.]

Machining the skin off any age of cast iron going to make it move and bend IMO. The skin imparts a lot of stresses into the part.

 

[Robotstar5]

Cast iron is a strange material, on the move for quite a long time when new which is why performance engine shops in the states turn engine castings out in the elements for about eighteen months prior to any machine processes. I think a used cast iron manifold that has had a skim is more stable than a new one.

Bob

When I worked in the Iron foundry they had rows of castings aging in the yard before they were dispatched to customers.

 

[bricol]

We've row upon row of cast iron machine bases outside in the sunshine (at the moment) seasoning.

 

[rtcosic]

Cast iron is a strange material, on the move for quite a long time when new which is why performance engine shops in the states turn engine castings out in the elements for about eighteen months prior to any machine processes....

Some years (decades!) ago I needed some machining work on my Jaguar XK engine. When I mentioned to the machine shop - which only did XK engines - that I had an old 'scrap' block, crank and pistons and was it any use to him, he reacted like a demented toddler overdosing on sugar!
He rebuild the head with new guides, upgraded valve stem seals, new valves, head skimmed and whatever else in exchange for my 'scrap' short engine.
He confirmed that the racers paid good money for used blocks - the older and higher mileage the better for just that reason.

 

[Kayos]

Is this where the story of people relieving themselves on BMW blocks destined for race cars comes from?

 

[brightspark]

Machining the skin off any age of cast iron going to make it move and bend IMO. The skin imparts a lot of stresses into the part.

yep you can get it heat treated to soften it and get rid of hard spots. i once had some castings done

 

[not done it yet]

Have a look here, starting at about one minute in.

 

[mtt.tr]

Have a look here, starting at about one minute in.

I didn't know he did videos that weren't him slagging of customers.