Technical What's the best way to clean this aluminum intake and valve covers?

I've got an Offenhauser 360 intake and some Cal Custom valve covers for a 302 I'm going to put together. They're both pretty corroded, the intake is especially bad. What's the best way to clean these up? I was thinking bead blasting, but I'm worried that would be too aggressive? I know sand blasting would be way too much. Or would some chemical/acid be better? Also, I want to polish the valve covers, would one of the drill kits suffice? Or should I get a buffing wheel for my bench grinder?

 

I would glass bead them. Works well on cast aluminum.

 

Glass beading will leave a surface that does not look original and is very hard to keep clean. Vapor blasting, if you can find someone who does it, will give you the closest thing to an original surface that can be done. Deep corrosion pits will remain regardless, unless you want to remove then mechanically before any surface treatment.

 

I was always told to soak aluminum in Pine-Sol to clean it. I never tried it. I would blast and polish or paint those items.

 

I like the finish glass beading leaves on aluminium

 

The local machine shop that I do business with has a cold tank to clean aluminum that does a pretty good job on grimy aluminum heads and intakes.
I don't like the look of sand blasted aluminum intakes and they tend to get grimy faster in my book.

 

I use tooth paste on old aluminum and works pretty good.

 

because of the poor condition bead blasting likely best. after that search for aluminum sealers to apply. polishing intake is very difficult with out right equipment. a strong power buffing wheel set up could be used on valve cover top of fins, etc. might just clean up and paint for good look.

 

For the valve covers, I would glass bead inside the fins where the corrosion is worst. Wet sand 220 up to 600 on the sides and polish. Polish the tops of the fins too. Inside of the fins would look kool either cast iron gray, or engine color.

 

When I was a kid we used 409 cleaner with a tooth brush on our mighty 305 honda scramblers.
Worked good, but yours I would glass bead blast

 

Napa sells a product called aluminum brightener. It's a mix of a couple different acids so it's pretty potent stuff (wear protection!) but I've had success with it on cast aluminum parts. It will dull previously polished parts, so they'll need to be re-polished.

Glass beading is another good way to go, or if you can find someone who does vapor blasting that will be even better.

 

Vapor blast or oxalic acid. I wouldn't go anywhere near an engine parts with a bead blaster, especially one that is heavily pitted. To much chance of the glass bead getting stuck in the pits with an obvious outcome when hot oil mist and fuel/air releases them.

 

I would bead blast them. HRP

 

Glass bead, run a DA over the letters, seal it with VHT satin clear.

 

The first thing you have to understand is that manifold will never look as-cast new again. And any deep pitting isn't going away. With that said...

For the manifold with its heavy corrosion in places, I'll recommend sand blasting with 80-100 grit sand over bead blasting. The reason is bead blasting tends to 'seal' the surface, and any remaining corrosion left in microscopic pits will reappear sooner or later. Yes, sandblasting is more aggressive, but IMO that's what it'll take. Learned that one the hard way when powdercoating. If possible, heating the parts at about 300 degrees for an hour will 'boil out' any remaining moisture and make removing the corrosion easier. This is a 'must do' if powdercoating aluminum castings with heavy corrosion. Sandblasting also leaves a better 'tooth' surface so any coating will stick better. I'd powdercoat it, but Eastwood makes a pretty good 'cast aluminum' paint.

As to the valve covers, I'd sandblast between the fins and any spots with heavy corrosion, but not the originally polished places that aren't showing any major pitting. Resist the urge to use sandpaper, instead do this... Projects - Weiand manifold polish | The H.A.M.B. There will be a small tool investment (HF angle head die grinder, a roloc arbor and half a dozen each of blue and gray 3" roloc discs). You should be able to have them final-polish-ready in about an hour or less. Use a sewn cotton buff with tripoli compound for polish, if you want mirror bright, follow up with a loose cotton buff with white compound.

 

Another voice that says it will never look as new. I've used glass bead and sand at different points. It will oxidize later unless coated.
If you have access to one in the area, another possibility is a media tumbler. This is going to be a production facility that deals with machining in most cases and may be against tossing your old stuff in with freshly machined parts, but it will turn out a nice, even finish. The little hobby ones are too small to do your parts.

It will still need to be polished if desired and nothing will fill the missing areas at a reasonable price.

 

Looking forward to seeing final results and what method(s) were used.

 

Wow! A lot of great suggestions here. I will post a follow up when I'm done

 

Poor mans tumbler.
Cement mixer full of pea rock.

 

I've cleaned up heavy aluminum corrosion using walnut shell media. It works well, leaves a nice finish and is safer than using sand or glass. Good luck!

 

Tried that once, was so noisy, I quit before the neighbors sicced the police on me.

Seriously; sand blast the manifold along with the areas between the fins. Wet sand the sides of covers and fins with 320-400-600 on a block, then use a decent buff with white compound to shine them up. Finish with paint between the fins.

 

Sand / bead blast
Put in the sun or under a heat lamp
Apply WD-40

Blasting will leave the white / brighter aluminum look.
The wd-40 will turn that look darker. Heating it allows for the wd-40 to penetrate into the pores / pits /casting imperfections.
You would need to re apply occasionally but spray it on wipe it off.

 

Just for reference. The intake manifold on the right is aluminum. I bead (glass) blasted it and then painted it with some aluminum coloured paint. Can’t recall which brand/type but could check if interested. I noted at the time, that the paint had pretty much the same colour as the freshly beaded surface.

Before.



Test section in middle of intake.



After with paint.

 

Oxalic acid is nasty stuff! Just opening a bag of dry OA will choke you if done inside! And it can cause your lungs to bleed if you don't have a very good respirator, even outdoors! It's sold in hardware stores as "wood bleach" and I use it to get stains out of wood, but only outdoors with a fan blowing the smell away, and a respirator and rubber gloves.

 

The jobs just beginning if you use pine-sol even in an ultra sound.

 

Active ingredient in BarKeepers Friend is Oxalic/citric acid, its diluted into a solution so it's a bit safer to use for average consumer. I use the spray to clean soap scum and hard lime water deposits off glass shower doors.

 

More thoughts on this
https://www.jalopyjournal.com/forum...luminum&o=relevance&c[title_only]=1&c[node]=5

 

Only ever used it in pre made liquid form on complete bodies and parts of pre and post war Rolls Royce, Bentley and the occasional 50s and 60s Ferrari. Always a good idea to follow the supplied health and safety data on any products. A lungfull of shotblasting glass won't do you any favours either if used incorrectly.

 

@Wobbly next you are going to tell us used motor oil isn't great as a pomade!

 

Tarn-X, as seen on TV