YYC - Resurface turbo exhaust manifold

[Former Member]

I would probably use 120, the second is I would place MDF at the bottom and let the wt of the manifold apply the pressure.

 

[PeterT]

I think having the abrasive attached to the surface would be the preferred way. You could check into sanding belt like 6" wide by whatever length & split so its a continuous uninterrupted abrasive surface for the entire push pull stroke. You could just use felt pen cross hatching across the manifold surface to monitor how the removal is going. I'm not an auto expert but guessing cast iron might be significantly harder on the abrasive than some of the vids showing alloy heads. So maybe not all belts would make the grade?

 

[phaxtris]

On man your going to be at that for a month of Sunday's with 120g by hand and It'll probabaly just make it real shiny

Cast iron isn't aluminum, 120 is hardly going to make a scratch never mind take off half a mill

I suppose a guy could do it in two passes on a smaller mill, just a lot more setup time

Or just pay an engine shop 100$ to do it

 

[digitalbilly]

I would probably use 120, the second is I would place MDF at the bottom and let the wt of the manifold apply the pressure.

First link has to be a joke.

 

[digitalbilly]

On man your going to be at that for a month of Sunday's with 120g by hand and It'll probabaly just make it real shiny

Cast iron isn't aluminum, 120 is hardly going to make a scratch never mind take off half a mill

I suppose a guy could do it in two passes on a smaller mill, just a lot more setup time

Or just pay an engine shop 100$ to do it

What nobody here has a mill at home?

I still would prefer to keep this within the hobbies community. but yeah Cast iron a much harder material than aluminum

 

[Former Member]

What nobody here has a mill at home?

I still would prefer to keep this within the hobbies community. but yeah Cast iron a much harder material than aluminum

What!!!!! You mean to say you don't have a mill at home.....shame on you......go get a piece of paper and write a 1000x "Go get a mill now" as punishment.

 

[terry_g]

What is the exhaust manifold off? What is the maximum allowable warpage? Looks like a Cummins ISB manifold.
Two piece manifolds you measure the two sections for warp individually. The joint between the two sections has a lot of "give" to it.
Cummins spec is .008" for the long section.

 

[phaxtris]

@digitalbilly I would say most of us have a mill, but I don't know how many have 59cm of x travel, i could do it in two passes, but don't have the time or enough fixturing stuff to set it up

Does it actually leak ? Or do you have it apart and checked it finding some warpage, as @terry_g said that 2 piece part has a good bit of flex to it

 

[Dabbler]

It will take longer to set up the piece on a mill than to lap it on a glass or granite plate. If you have to do 2 passes, you have to take *extra* care to make sure the two cuts are coplanar. That will more than double the setup time.

Lapping is the best way to go.

 

[digitalbilly]

I think giant belt sander would be ideal.

 

[Dabbler]

None of has a a 6" sander with a 28" platen. Seriously it isn't a lot of work to do it by hand,

 

[Susquatch]

Don't know how I missed this thread.

How do you know the exhaust ports on the head are planar? If you are not going to do the head then you might help or hurt the exhaust manifold fit.

Since I don't read anything in the thread about doing the head, I assume that isn't in the plan. Therefore, before I touched the exhaust I'd check the fit between the two. Just put them together with no gasket and use feeler gauges. You might be pleasantly surprised to find out how well it fits. Or you might discover it's worse than you anticipated looking at the manifold alone and your simple job just got a whole lot more complicated. But better to know than not.

Assuming there is nothing in the way, you can also use a straight edge on both parts.

If you really have to do this yourself, I am in @Dabbler's court on how to flatten it. I think you will probably be disappointed in how a milling job turns out even with a big mill table. But just for the record, I personally recommend bringing it to a good engine shop. It's peanuts in the big picture. Many of those shops will do it in exchange for a donation to their coffee fund or some cash on the table.

My two cents for what it's worth.

 

[Former Member]

Look even with a small mill it could be done, would I no, for the simple reason to get a good result the set up time(s) alone would far exceed the time to do it hand to get the same result.

Know your tools, maximize the results for minimum effort in the shortest time.

 

[DPittman]

Many of those shops will do it in exchange for a donation to their coffee fund or some cash on the table

Wow I don't think you'll find that sort of deals with any good engine shop around here! I imagine shop rate is at least $150/hour and minimum charge must be at least that as well? That's alot of donuts.

 

[Susquatch]

Wow I don't think you'll find that sort of deals with any good engine shop around here! I imagine shop rate is at least $150/hour and minimum charge must be at least that as well? That's alot of donuts.

You might be right. The Windsor/Detroit area is the collective motor city. There are engine shops and hotrod shops everywhere. It's like a hobby for a lot of them. Some of them don't even do it for a living. There is a race track 5km away from me and a racing car in a garage on every block.

You are probably right, it might be a lot different out west.

It doesn't change how I think though. Setting up to mill an exhaust manifold and then actually milling it with good results is no piece of cake in a hobby shop. That's why I prefer sanding on a flat block.

On the other hand, engine shops do that kind of work regularly and are setup to do it quickly. But they typically do entire engines or short blocks or complete cylinder heads. Mounting and resurfacing an exhaust manifold should be an easy side job for them. Finding someone to do it at an affordable price might not be so easy out west. You might have to pay through the nose. But at least that way, you could expect them to stand behind their work.

 

[terry_g]

I had a couple exhaust manifolds off a 1976 Tucker Sno-Cat with a 318 Chrysler engine that had shrunk
and warped quite badly. They were leaking badly and we needed the machine. I took the manifolds to
two machine shops and neither one wanted to do the job. I finally talked the second shop into doing them.
Resurfacing the manifolds helped but did not fix the problem as after a few hours the gaskets started
leaking again.
I ended having to remove the cylinder heads and have the manifold gasket surface on the heads resurfaced as well.

 

[digitalbilly]

hey guys thanks for all the info
my head is flat and within factory spec so I only need to worry about the manifold.

I got some granite pieces and also have some extra anyone needs a piece let me know

I figure I'm gonna start with 60 grit then 80 then finish 120 grit.

 

[Former Member]

See some on the group has done it.

Mini milling machine

As long as you are learning, it is always good. If one is learning, then they are interested. If your interested it’s almost as work becomes like a hobby more then “work”.

canadianhobbymetalworkers.com

 

[digitalbilly]

I did it and it came out great for it within 0.04 pretty flat for my needs

 

[Susquatch]

I did it and it came out great for it within 0.04 pretty flat for my needs.

So tell us how you did it!