[Green Hornet]

I want to clean some old cast iron intakes I have on the shelf...

They are as removed....with grease,old paint and rust......and some have some rust in the plenum under the carb mounting flange....

Just exploring my options....speed vs cost.....vs quality of job....

Electrolysis.......muriatic acid...media blasting.....Evaporust soak?

Done the wire wheel \ wire brush route before.....

Looking for some input.....Thanks

[i82much]

wife.

[phil400]

I did this about 5 years ago, but I cleaned up a 72 intake with a wire wheel then soaked in plain ole white vinegar for a few days maybe a week then knocked off the loose stuff with a wire wheel after soaking, intake came out alright but my stuff idmsnt high dollar builds, included some before and after pics

[Green Hornet]

Originally Posted by phil400

I did this about 5 years ago, but I cleaned up a 72 intake with a wire wheel then soaked in plain ole white vinegar for a few days maybe a week then knocked off the loose stuff with a wire wheel after soaking, intake came out alright but my stuff idmsnt high dollar builds, included some before and after pics

Thanks for posting all the pics/info....

I also have a 78 Ta that I've owned for a long time...

[Green Hornet]

Apparently....Muriatic acid....will potentially damage intake if left too long in the soak...
Phosphoric acid would be a better choice..

[phil400]

More pics, afterI was done I used brake clean the coated it with WD till I was ready to paint

[phil400]

Another pic

[phil400]

Here it is painted, sorry for all the posts, was years ago had to go searching through my phone for the pics,I also painted the exhaust crossover with several andI mean several coats of high header paint to slow the engine paint burning off and rusting, several years some discoloration but no rust

[1968GTO421]

When I was in AACA years ago, one of the guys used electrolysis, putting the part in a large tub with leads from a battery. One lead went to a clamp on the part and another to the metal tub (if I remember correctly). His technique worker great on some really funky parts. I really like Phil400's method as it does not involve electrical stuff and possible shocks to curious kids and others. Thanks, Phil.

[Green Hornet]

Originally Posted by 1968GTO421

When I was in AACA years ago, one of the guys used electrolysis, putting the part in a large tub with leads from a battery. One lead went to a clamp on the part and another to the metal tub (if I remember correctly). His technique worker great on some really funky parts. I really like Phil400's method as it does not involve electrical stuff and possible shocks to curious kids and others. Thanks, Phil.

I'm just setting up to experiment with electrolysis......and also muriatic acid soaking.....

[Schurkey]

Originally Posted by 1968GTO421

When I was in AACA years ago, one of the guys used electrolysis, putting the part in a large tub with leads from a battery. One lead went to a clamp on the part and another to the metal tub (if I remember correctly).

He wouldn't put a lead on the metal tub, or the tub would corrode and leak. And the leads have to stay dry, so connect the leads to welding rod or whatever, bolted or welded to the part you want to save, and the sacrificial metal.

Electrolysis removes rust. Any de-greasing is entirely incidental, it'd be like dunking the part in mildly-soapy water for a day or two. Ideally, the part is completely degreased/cleaned before being de-rusted by electrolysis.

He'd put a lead on a sacrificial piece of steel, with the sacrificial metal close to the piece to be de-rusted as possible but NOT TOUCHING. Ideally, a piece of sacrificial sheet-metal, hammered/pounded/formed to sorta-conform to the shape of the piece to be de-rusted.

The cleaning works best when the sacrificial metal is close. So the back-side of the part won't be de-rusted. The farther away the sacrificial steel, the less-well the cleaning action.

I played around with electrolysis for awhile, even bought a 24-volt battery charger to speed things up compared to a 12-volt charger. The suggested electrolyte was water plus WASHING Soda. (Not "baking soda".) Washing soda was harder to find--had to go to several stores before I found some next to all the laundry detergent.

I don't remember which way the battery charger leads are connected. Get it wrong, and you'll have a de-rusted sacrificial metal, and the part you wanted to clean is even worse.

I'm thinking this works on iron/steel but NOT aluminum. When it works, it works really well. But getting the sacrificial metal close enough to the area of the part to be de-rusted is tricky.

A DC welding power supply at higher voltage still would be better than a battery charger.

[Skip Fix]

The exhaust crossover junk is something to be sure is all gone and not just loosened up to be blown into the ports on the other side regardless of what you use.

[mgarblik]

If you have a machine shop in your area with a thermal cleaning process, that is simple and easy. They will look like new manifolds when they come out, inside and out. A shop around here would probably charge $50.00-75.00 to run a load. Our drum would hold maybe 6 intakes. So per manifold, pretty reasonable.

[Green Hornet]

Originally Posted by mgarblik

If you have a machine shop in your area with a thermal cleaning process, that is simple and easy. They will look like new manifolds when they come out, inside and out. A shop around here would probably charge $50.00-75.00 to run a load. Our drum would hold maybe 6 intakes. So per manifold, pretty reasonable.

I local guy here quoted me $300...to run a load/batch....so I crossed that off my list.....

Does that process remove rust...or just paint/grease?

[mgarblik]

Originally Posted by Green Hornet

I local guy here quoted me $300...to run a load/batch....so I crossed that off my list.....

Does that process remove rust...or just paint/grease?

That is a very high price. $300.00 worth of thermal cleaning here would do an entire engine. Block, heads, crankshaft, manifolds, and sheet metal. Typically 3 full loads. So maybe $100.00 a load now.

Parts come out like new castings from the foundry. No rust, paint or anything else, inside and out. We bake iron in a slow rotating drum at about 650 degrees F for an hour. Then it goes directly into a stainless steel shot machine with .030" tiny steel wire shot for 45 minutes.

Where are you located?

[Green Hornet]

Originally Posted by mgarblik

That is a very high price. $300.00 worth of thermal cleaning here would do an entire engine. Block, heads, crankshaft, manifolds, and sheet metal. Typically 3 full loads. So maybe $100.00 a load now.

Parts come out like new castings from the foundry. No rust, paint or anything else, inside and out. We bake iron in a slow rotating drum at about 650 degrees F for an hour. Then it goes directly into a stainless steel shot machine with .030" tiny steel wire shot for 45 minutes.

Where are you located?

I have no concept...of what anything costs anymore.....

Figured if that what the price was....I would find an alternate method...

I'm north of Seattle...about 150 miles...

[unruhjonny]

honestly, if you put a little bit of effort into it before worrying about the rust, your time invested will be well worth it.

Take them to a pressure washer to get the grease and oil off;
Then a soak in evaporust(ect) will prove astonishing results.

[Half-Inch Stud]

An electrolysis, lemon juice, oxalic acid, snd such may be woryh it for 3 or more manifolds.

[lust4speed]

1967 intake manifold media blasted with #7 glass bead and an early hub/balancer assembly.