Polishing an Aluminum Manifold

[GPModJ]

I'm in the middle of polishing an aluminum manifold and--what a lot of work! *I'm starting with 80 grit sandpaper, moving to 120, then 240, and finally 320 before I polish with a cloth wheel and rouge.

What I'm wondering is how do you get into those tight spots like where the runners meet or where the runners, the plenum, and the base meet (i.e. there are three planes meeting in a corner). *I've got some small grinding bits for my die grinder but they're pretty coarse. *

Anyone have a better idea of how to get into those spots?

UPDATE: I've broken down and ordered a manifold polishing kit from Eastwood. The kit includes a how-to "manual." I'll post what I find when I get the kit & do the work.

[GPModJ]

Here's another update. If you order from Eastwood & you're located in Canada, Eastwood ships only once per week--Friday. So, order on Wednesday or Thursday if you want something shipped to Canada right away.

[GPModJ]

I got the manifold polishing kit from Eastwood today. Here's what's included:

die grinder mandrel for sanding cylinders & cones
die grinder mandrel for mini polishing wheels
drill mandrel for 3" polishing wheels
10 80 grit sandpaper cones
10 240 grit sandpaper cones
10 320 grit sandpaper cones
10 80 grit sandpaper cylinders
10 240 grit sandpaper cylinders
10 320 grit sandpaper cylinders
2 felt tipped cones for die grinder
2 3" cloth polishing wheels
10 or so mini cloth polishing wheels
Instruction manual
Cylinder of grinders grease
Cylinder of Tripoli rouge
Cylinder of Jeweler's rouge

Sanding cylinders and cones are about 1/2" in diameter and about 3" in length. I've used some of them and they work well once you get the hang of it and they allow you to get into some tight areas.

That being said, I got rid of the webbing on the manifold to make the polishing easier and to allow you to see the polished aluminum valley pan under the manifold.

The sanding cylinders tend to dig into the aluminum a little if you're not careful. I think you need to use sandpaper to smooth out the surface if you don't want to end up with a wavy surface in the end.

[LonnieS]

Excellent info, GP! Thanks for the contribution. ;D

[GPModJ]

Happy to contribute! :)

I'm planning on posting some photos of the finished product, along with some other notes on my experiences polishing the manifold.

[GPModJ]

Well, I'm almost done polishing my manifold and it's looking pretty good. I'm not sure I'll do this again though, as it's a ton of work just to get the manifold looking pretty. Here are some of my thoughts on polishing the manifold & the Eastwood kit:

Tools Used:

- Black & Decker "Mouse" (stole it from my wife)
- 3/8" drill w 1/4" bit
- Jigsaw
- Sawzall (reciprocating saw)
- Rubber sanding block
- Flat file
- Round rasp
- Die grinder
- 4.5" angle grinder
- Bench grinder

Supplies Used:

- 10 sheets of 80 grit pads for "mouse"
- 5 sheets of 120 grit pads for "mouse"
- 3 sheets of 240 grit pads for "mouse"
- 20 sheets of 80 grit sandpaper
- 6 sheets of 150 grit sandpaper
- 10 sheets of 220 grit sandpaper
- 8 sheets of 320 sandpaper
- 10 - 80 grit grinding / sanding cones
- 5 - 80 grit grinding / sanding cylinders
- 6 - 240 grit grinding / sanding cones
- 4 - 240 grit grinding / sanding cylinders
- 5 - 320 grit grinding / sanding cones
- 1 - 32- grit grinding / sanding cylinders
- 6 - grinding stones for die grinder
- 1 - 4.5" 50 grit sanding disc
- 3/4 tube of grinders grease
- 1 tube of Tripoli Rouge
- 1/2 tube of White Rouge
- 2 - 3" cloth polishing wheels
- 4 - 2" cloth polishing wheels
- 4 - 1" cloth polishing wheels
- 1 - 6" cloth polishing wheel (not used up)
- 2 felt-tipped polishing bobs
- 1 - 8" cloth polishing wheel (not used up)

Comments:

The Eastwood kit comes with lots of grinding cones and cylinders, which you can't do a good job without. However, I wouldn't recommend polishing a manifold with just what comes in the Eastwood kit. The cones and cylinders can be used to grind and sand the entire manifold but you'd end up with a really bumpy (but shiny) surface. The cones and cylinders create depressions in the surface--even when you're using 320 grit. I recommend using the Eastwood material for confined areas but sticking with plain old sandpaper for flat or slightly curved surfaces.

To remove some of the harder to reach spots, I started by removing the webbing between the runners, plenum, & base. To do that I used a drill so I could get a jigsaw blade in to remove the webbing. After the jigsaw, I (very carefully) used a sawzall to remove some additional material as close to the runners as I could get.

Underneath, I used a 4.5" angle grinder and a 50 grit disk to get rid of the casting texture. I wasn't all that careful and there are some minor gouges underneath but no one's going to see there, except for some reflection in the aluminum valley cover. I also (very carefully) used the 4.5" grinder to help remove some of the webbing.

The round rasp and file came in handy for removing some of the webbing, where it met the runners or plenum.

After removing the webbing, I used a die grinder, some grinding stones, and the Eastwood 80 grit cones and cylinders to remove any remaining webbing.

With all the webbing gone, I worked the surfaces with finer and finer sandpaper--using the Eastwood cones and cylinders to get into the hard-to-reach spots. Although I used 80, 150, 220, and then 320 grit sandpaper on the surfaces, Eastwood expects you to go from 80 to 220 grit with its cones and cylinders, which can cause problems, as while polishing I found grinding marks in some confined areas.

I used the bench grinder and an 8" polishing wheel to polish at all the easy-to-reach spots--particularly the underside. I've used the Eastwood felt polishing bobs and small cloth polishing wheels to get at the confined areas, such as where the runners meet. You you need to take care when getting at these hard-to-reach areas, as the metal cap on the polishing wheel can scratch a just polished surface. I know I've done it a few times now, which means I had to polish out the scratch or gouge.

I'm just finishing up tonight (I hope) with the final bit of white rouge. I'll post photos.

[LonnieS]

Great, GP - got any pics of your work? This is good for those who may be doing this work later.

[GPModJ]

I've finally got some photos of the final product to post. However, I didn't take them until I had the manifold on the engine. Anyway, here they are.

[GPModJ]

Here's another. . .

[GPModJ]

And a last one. . .

[canonbkr]

WOW!!!! That looks great! Did you apply any kind of coating to keep the oxidation down? How many hours did you finally end up with in this one?

Good Job!!!

[GPModJ]

I spray bombed the manifold and aluminum valley pan with clear engine enamel. I almost died when I sprayed the first coat on, as it turned milky. When it dried though, it cleared up.

Regarding the time required, I have about 35 hours into the polishing. From what I've learned from others, you can spend anywhere from 30 to 50 hours--depending on the manifold and how nuts you want to get about doing a good job.

[THOR]

lOOks very cool, nice work !
8)

[canonbkr]

Very Nice!!! Thanks for the feedback...

Obviously worth the effort!