Cleaning an intake manifold?

[orangeblood]

looking for coaching / suggestions for cleaning an intake manifold from a 1969 Firebird.

It was removed and is being replaced with an Edlebrock during restoration. I dont expect it will ever be remounted on the car but I want to keep it along with the other original parts that are being replaced. I'd like to paint it original Pontiac engine metallic blue.

I have pressure washed it and steel brushed it but a lot of rust remains. The attached photos are before and after.

Media or soda blasting or evaporust?

Looking forward to your suggestions.

 

[Showkey]

Media blast, vapor blast or soda blast would all work........soda is not very effective on rust, so media first then soda or glass beads to get the surface texture desired. Vapor blast might be the best choice.........

Obviously cleaning after any media to remove media debris and dust is critical.

 

[JamesW84]

electrolysis works wonders and is pretty easy to do. I think it works better on the perimeter of parts. I did it on a backhoe stabilizer and it worked awesomely.

 

[jayoldschool]

Get a bucket. Dump bulk jugs of vinegar in bucket. Put manifold in bucket. Take out a few days later. Rinse, dry. Paint.

 

[alwaysFlOoReD]

Get a bucket. Dump bulk jugs of vinegar in bucket. Put manifold in bucket. Take out a few days later. Rinse, dry. Paint.

This.

 

[Stuart in MN]

It's a two barrel manifold so it's not likely that someone would want to put it back on the engine in the future, but I understand the idea of keeping it around just in case. Simplest thing would be to just leave it as is, and only worry about it if that day ever comes. It's not going to get any worse just sitting on the shelf.

If you do clean it, use some method that won't leave any abrasive material behind. Sandblasting is definitely a no-no, even glass beading will be difficult to clean out of the internals and you don't want that stuff getting into the engine. Vinegar is probably the safest option.

 

[PWC Repair]

My go-to is a plastic bin full of water then add muriatic acid. Then dip in a water and baking soda mix to neutralize. Then rinse and dry with compressed air.

 

[larry4406]

Be mindful of the machined surfaces with any blasting process.

 

[NUTTSGT]

Be mindful of the machined surfaces with any blasting process.

Yes, duct tape or two layers of good masking tape.

 

[orangeblood]

THANKS for the input.

Jay / Always Floored - will vinegar be a problem with cast iron?

Stuart - you are right about the lack of 2 barrel demand; i am going to a FiTech system and cannot imagine ever wanting to go back....its just that i am keeping everything so that someone some day can (if they want) go back to 100% original on a numbers matching car

thanks again

 

[joe_padavano]

A two barrel iron intake isn't worth scrap value. Sorry. The only way to properly clean it is to take it to a machine shop that has a real, caustic hot tank (not these crappy new steam cleaners). This is pretty much the only way to get all the rust out of the cooling passages. Unfortunately, if you do this now and put it on the shelf for 20 years, the rust will have come back unless you pickle the intake in oil.

Bottom line, any attempt to do this now is a complete waste of money, especially when you scrap it in 20 years because no one wants it.

 

[67carl]

I have some rusty vises and when the time comes, will disassemble them and try electrolysis. There's a number of threads on GJ about it. Here are a few;

https://www.garagejournal.com/forum/showthread.php?t=154196

https://www.garagejournal.com/forum/showthread.php?t=56634

Got pics of the car? I installed an Edelbrock on my 67 - the RPM Air Gap.

 

[Robby321]

Get a bucket. Dump bulk jugs of vinegar in bucket. Put manifold in bucket. Take out a few days later. Rinse, dry. Paint.

just do this first...

 

[58Yeoman]

I put an Edelbrock on my Chevy years ago, but didn't like trying to keep it looking good. I ended up painting orange to match the engine.

 

[jayoldschool]

THANKS for the input.

Jay / Always Floored - will vinegar be a problem with cast iron?

thanks again

Problem? It's like magic. Chemistry is amazing. Has to be iron or steel. Go to Costco/WalMart/whatever and buy a case of four big jugs. Take crappy parts, throw in bucket. Remove clean rust free parts. Not kidding.

 

[Docbentley]

Looks to me like that manifold has a couple cracks anyway, just junk it or use for boat anchor

 

[VTX1800]

I hate to comment, I like to be positive, but a two barrel manifold is worth it's weight in scrap value, I buried one in concrete instead of re enforcing rod. If it has sentimental value then vat it or blast it and paint it, then hang it on the wall as garage art.

 

[rustyjames]

I hate to comment, I like to be positive, but a two barrel manifold is worth it's weight in scrap value, I buried one in concrete instead of re enforcing rod. If it has sentimental value then vat it or blast it and paint it, then hang it on the wall as garage art.

I like to be positive too, but if you used an intake manifold for reinforcing concrete you didn't reinforce the concrete, instead created a stress point for it to crack.

 

[Stuart in MN]

Looks to me like that manifold has a couple cracks anyway, just junk it or use for boat anchor

That's the way Pontiac intake manifolds were built, they aren't cracks.

 

[vpd66]

If you want that intake spotless clean. Take it to an Automotive machine shop. They will bake it, hot tank it, and shot blast it and it will look like brand new raw cast iron. I've never been charged more then $30 to have it done.

 

[Falcon67]

Above is correct. You can glass bead it but you best wash the ever'lovin **** out of it. Any stray beads will make hay with the rings when it's back in operation. Soda would be better, bake and wire abrade at a machine shop would be best.

>two barrel manifold is worth it's weight in scrap value,
Maybe, maybe not if someone needs one for a resto. These things aren't laying around in the wrecking yards like they were in the 70s. Nearly every part of these older cars may now have value to someone.

 

[mike93lx]

Unless you want the project, maybe just coat it in a corrosion inhibitor and wrap in plastic. Put on the shelf and throw it away in 20 years when you are cleaning up.

 

[atthebeach]

I have used vinegar on rusty, hot rolled plate prior to welding with very good results. After quite a bit of use it is no longer effective, and I have a gallon ready for disposal. What is the best way to safely get rid of it?

 

[Lonnies Performance]

Getting the sand out isn't that hard... keep in mind it was made from a sand casting to begin with. Will take about 2 minutes with an air hose to get it all out.

The only hard areas to get sand out of is under the heat shields on the bottom of some factory intakes. This one has none of those shields to worry about.

Someone will likely blast it for what you spend on vinegar.

 

[mike93lx]

I have used vinegar on rusty, hot rolled plate prior to welding with very good results. After quite a bit of use it is no longer effective, and I have a gallon ready for disposal. What is the best way to safely get rid of it?

It's is just vinegar and scale. Dump it down the drain

 

[atthebeach]

It's is just vinegar and scale. Dump it down the drain

I'm not sure I want that in my septic tank. Any alternative approaches?

 

[LS6 Tommy]

I'd go Evaporust. If you media blast it, get it hot tanked afterwards.

Tommy

 

[38Chevy454]

I'm not sure I want that in my septic tank. Any alternative approaches?

It's not hazardous, but could still be a little acidic. Just wait for a rainy day and dump it in the street gutter. It will only smell bad until the water washes it away. If you dump it in your yard it could smell like vinegar for a while, and the acid may burn any grass in the area.

 

[alwaysFlOoReD]

Neutralize vinegar with baking soda. Get a ph strip to test if worried.

 

[ScottsGT]

Son called me a few weeks back about a set of heads with the same rust. I told him about the vinegar trick.
He said they look new now.

 

[rattle_snake]

I like to use Muratic acid over vinegar because you can adjust the strength/ph as needed.
Suggest gloves/eye protection.

 

[69supercj]

I have used vinegar on rusty, hot rolled plate prior to welding with very good results. After quite a bit of use it is no longer effective, and I have a gallon ready for disposal. What is the best way to safely get rid of it?

Pour it down the sink or toilet if its chunky.

 

[Jazz1]

Vinegar will eat cast iron. I left a brake drum in vinegar just to see the damage caused. Evaporust may be a better solution. Worthless scrap, not to someone doing a original restoration.
I have done a frame off on a '68 firebird.

 

[Stuart in MN]

Vinegar will eat cast iron.

It's a matter of how long you leave it in, and if you neutralize the vinegar when you take it out.

 

[22george]

9 parts water one part molasses. Leave in for several weeks. Clean with water. Dry off. Corrosion protect. ( Molasses will start to stink)

 

[Koldham]

iv cleaned som pretty rusty cast iron cookware in the ovens cleaning cycle.

 

[bbxlr8]

Clean it per above, paint it and stick it on the shelf or wall. Never hurts keeping old good parts...

 

[rburke65]

I initially found it hard to believe what a great job vinegar does. 5% acidic. Very gentle.