[ho428]

Got a good 400 block to start building, been tanked and magged but it still pretty rusty. Bores and galleys are ok but mostly anything unmachined is surface rusty.
I had one shop advise against using chemicals like evaporust on it, didn't give a reason though.
Anyone used that on a block before?
Other than a wire wheel and hours of time what other options are there?

Going with splayed caps and some oiling mods, typical bore and deck.

[steve25]

I had a block like that once and I payed a shop 25 bucks extra to toss it in there glass bead buncker.
You will need to tape off all of the oil passages and have the person doing the beading stay away from such.
Once back in your hands you will need to blow it out top to bottom very well, but it will be spotless!

[Sirrotica]

Rust removal using electrolysis:

https://www.youtube.com/watch?v=NKZv14-K71g
https://www.youtube.com/watch?v=AQNvhUYqCkw

Rust removal using vinegar:

https://www.youtube.com/watch?v=TlcL_vHODkc
https://www.youtube.com/watch?v=eSK2UeJRMIM

Neither remove any material from the parent metal surfaces.

[ho428]

Called every shop in town, think I found one that'll bake and shot blast it for $50
Never had one done but doing an internet search looked to be the most recommended method.

[mgarblik]

Bake and blast will produce a fantastic rust free surface, inside and outside. If their blast system uses tiny stainless steel shot like mine does, the water jackets around the cylinder bores will be clean as well. Keep in mind that every machined surface will require attention after blasting. At a bare minimum, deck will need to be surfaced, cylinder bores of course, line hone, and lifter bores honed. May need some additional dressing here and there too. You will need to spray the block immediately after blasting with rust inhibitor. Otherwise, it will be rusted again in a day or 2.

[ho428]

What would you recommend as a good rust inhibitor? Most of the stuff we have at work is thick goop for large shafting and long term storage.

Planning on splayed caps and line bored, boring either .040 or .060 over and deck.
Hopefully he'll stay somewhat clear of the lifter bores, but I might tap them for restrictors anyway. Haven't decided on that yet. Usually just run restrictive push rods.

[mgarblik]

For long term storage, I also like the goop type stuff. One of the best I have used is called Gel Lube in a spray can from VALCO Cincinnati. I think you can buy on the web. It sprays on thin then jells-up as it sits. For after cleaning and when going on to machine, I just use WD-40 in a squirt bottle, not the aerosol can. Get the block wet with it and it will not rust for a few weeks. The one downside to WD-40, is you will have to really scrub the block with soap and hot water thoroughly if you want it to hold paint. I am sure others will chime in with better suggestions.

Typically, bake and blast is not a hand operation, so everything will be blasted. Lifter bores generally just need 5-10 passes with a ball hone. No big deal there. It's just an annoying surprise to be assembling the fresh engine and realize none of the lifters will fit in the bores. Then you have to re-clean everything again and possibly re-paint. Just a head's up.

[Skip Fix]

Years ago I used some spray on antiseize on some of my 409 cranks and blocks. My dad moved some pool chlorine just in the garage area-rusted the bicycles nearby but no rust on those parts!

I had one 400 block I picked up from a local guy that had a lot of surface rust-shop sent it over to one that had the bake and bead and looked great! They just did not use better dowels when they did the 4 bolt caps!

[BruceWilkie]

I like bake n blast process... My old machinist did that...used easy off oven cleaner and then blasted. One of my blocks had heavy flaking crust on outside but water jackets were very little rust...looked new when done other than a few scars where the crust was. When he finished machine work and final clean he'd paint your block and/or heads(if you supplied it) before oiling machined surfaces(Marvel Mystery Oil) and bagging.

He hated working on dirty/rusty stuff and when dropping stuff off it didnt come in front door it went to the cleaning room. He charged 2 extra hrs labor and rest of his pricing was competitive with other local shops. Wish he was still with us.

I've used electrolysis on smaller parts with good results.... Havent tried soaking an entire block...yet.

A crusty exhaust manifold came out nice...the rusty bolts that were still holding the pipe flange on de-rusted and it took little effort to loosen them after the soak.

I've used re-bar and other scraps of steel or iron for electrodes... the closer electrodes get to part the higher the amperage on my charger and faster it seems to work...when electrodes get too crusty the amperage drops and process slows.Cleaning them periodically keeps the activity moving. Keep your positive cable out of the solution...it will get ugly fast and eat it.

One of the vids above used carbon graphite... I'd like to source some.

[Half-Inch Stud]

despite what they might say: bolt the Caps & junk Main bearings in. Cam bearings in. Shot blast will be good then. Maybe plug head bolt threads?

[ho428]

Caps are on but all bearings and plugs are removed and gone.
I can chase all the threads afterward, my concern would be the cam bearing bore and the freeze plug bores getting dimpled during the blast process.
This guy has done this type cleaning many-many times, runs a full machine shop, but I've yet to talk to him in person to go over any concerns.

[taff2]

Evaporust is pretty good I find, probably a bit expensive to fill a big enough container to dunk a whole block in though. It doesn't take off paint or grease either.
I used to get my block and heads dipped in a hot caustic tank by a local company that stripped doors/furniture etc,when they closed down I made a steel tank big enough to fit a block and pair of heads in and mix my own caustic soda solution. With a gas ring under it to heat up the solution. It takes off paint,oil and most of the rust that accumulates in the water jackets, just needs a good jet wash after. Don't get it on your skin or in your eyes!

[darbikrash]

Lifter bores will need to be addressed after blast. Top of bore is often peened over.

[77 TRASHCAN]

There used to be a company in Oklahoma City, don't remember exact company name but, "metals stripping" was in name. They have been out of business for some time.

But, the process was a reverse plating process. I took them a set of heads, they came back looking like fresh cast iron, absolutely perfect. I wonder if you could find such a place I your area...OR possibly call some plating shops that might know of someone that performs such a service.

Another thought..sometimes when I get a carb to work out on, it will have corrosion in it. I use Lysol toilet bowl cleaner. It's a mild acid, I only leave it in the carb for a few more muted at a time, to make sure it doesn't create a worse problem...You'd have to buy several bottles. It might be do-able with the freeze plugs installed, you could fill one bank at a time. Rinse with baking soda at end to neutralize any leftover acidic solution in block..

[Sirrotica]

Redi Strip was the outfit/franchise that did whole car dip, not many if any around under that banner any longer.

[lust4speed]

The shake and bake from my local shop has the block looking like new cast iron. I always leave in the cam bearings and (as said above) secure the old main bearings in place before dropping the block off. I haven't had a problem with the lifter bores, but I wonder if the shop doesn't touch them up.

[mgarblik]

My cleaning system, which was marketed by Sunnen for about a decade is a rotisserie drum type system. It slowly rotates the parts to apply even heat to the castings. Primary burner 80,000 BTU. I cook iron at 600-625 degrees F. The block bolts to the drum through the mains, so the bearings and caps have to be off. They are cagged-in separately and rotated. Cam bearings can be left in place but are very difficult to remove after cleaning. You can't use the typical cam bearing expanding remover as the edges of the bearings are peened over or rounded so the mandrel will not bite the bearing. If you use a precision solid driver, the bearings will come out. My best practice is to remove everything you plan to remove from the block and heads before cleaning, this includes dowel pins and pressed head studs. After cleaning, it is nearly impossible to remove pins and studs without drilling them out in a mill. The oven bakes the residue round these parts and really fuses them in the block and head. The above method has worked well for me for about 20 years. We bought the equipment in 1998. A quick ball hone of the lifter bores and cam bores and you are good to go. Other machined surfaces need proper precision machining.