Unseize a Frozen Engine

[Topcat]

I actually read years ago that soaking an engine block in a mix of Molasses and water will free up frozen blocks.
It might take up to week.
Molasses is cheaper at Feed stores.

Afterwards get it all hot tanked.

[jimynick]

You want to check the bores and make sure there's no ridge at the top before you try to drive those old slugs out. If there is, it's likely the rings will catch on it and then you'll need to go to the 50lb sledge! As mentioned, the pistons are scrap anyways, so see if you can get the crank out of it and if so, then drive those old s.o.b.'s out the bottom. Wood is your friend here, because a steel tool could put a bigger ding ina cylinder wall than you'll get out with a standard overbore. The other thing, which I didn't know existed before it happened in my own old 340 block, is that cast iron is actually porous and hard core rust can penetrate deeply into it. We machined my bores .030" over and they appeared to be good, BUT, when you let the block sit for a day or two, the rust would start to bleed back out. We ended up having to go .040" to stop that. Just FYI. 

[1970Cuda]

Yes, I did check and the bore tops had no ridge. Actually it's too bad person who owned this before I did left it out in the weather (grrrr), because I probably could  have gone with a standard bore. Unfortunately now I'll likely need to go at least .030", probably .040" over and maybe I'll need to sleeve it. Still, it's the original block, so it makes sense to salvage it.

Also, I didn't know that if I remove the crank the pistons would come out the bottom. Are you certain this can be done? I think I have enough of the pistons out that maybe I can remove the crank. I'll have to check. Because I have at least two pistons that are at the bottom of their travel, so that'd be awesome. It would certainly be easier (likely) that trying to remove them from the top. Thanks for the great suggestion!

[1 Wild R/T]

The pistons are junk, you want to save the block.... Use a hole saw to cut away the majority of the piston dome.... Then a few holes out near the side of the piston top... That will allow the piston to collapse some... Not saying it will cause the pistons to fall out but it will weaken the piston reducing the likelihood of damaging the cylinder...

[1970Cuda]

Update on Frozen Engine

I wanted to follow-up on this ancient thread to provide a "Good News" update. ....

I was able to remove four of the eight frozen pistons in the block, but had stalled out my progress because – unfortunately, I had shoulder surgery and then of course recuperation and rehab. It actually worked out really well to be honest, because I kept using my Gibbs penetrating oil on the cylinder walls, both from the top and underneath, near the piston skirt (lower cylinder wall, block interior).

After allowing the engine to sit around for approximately 1.5 years, I was able to once again attempt to remove the remainder of the pistons. (I have been using a nine-pound sledgehammer and a 1-inch solid steel rod, that was being cushioned by wood bock pieces arranged around the crankshaft and block locations. I was hoping to salvage the crank.)

It was amazing because after all that sitting and oil working its way into the block and piston areas, I was able remove an incredible three pistons within 1.5 hours! I was actually a little shocked TBH. The following day, I tackled the last remaining piston (which was at the lowest point in its crank travel, at the bottom of the block) and I also remove this last piston. Whohoo! See picture below.

I have read previously that it is very possible that because of how rust behaves, I will need to sleeve the block, but at least I will be able to salvage my original engine. From what I observed only one cylinder is badly rusted. And based on my read of the block markings, all cylinders were standard bore.

Thanks to everyone for providing suggestion for removing the pistons. It was much appreciated.

[headejm]

Congratulations! Hopefully you have access to a good machine shop. You'd be surprised what 0.030" oversized bore will clean up. You could even go up to 0.060" if you started with standard bore size. I wouldn't "plan" to sleeve any of the cylinders until your machine shop says you have to. Good luck and keep us posted. 

[1970Cuda]

Thanks – I was surprised that I was actually able to complete the piston removal (see another picture).

And you are right – it might clean up to 0.30 over, which would be great, and if not, I will probably see if 0.40 would work (even though that is a custom piston). I am thinking I do not want to go 0.60 over TBH. I have a good machine shop that is local. Although, there is a top-notch machine shop that I might take my original block to, that is significantly more expensive, but is super high-quality work.

In the meantime, I am planning on building a stroker (I think it is a 434 CID) with another 1970, 383 CID block that I own. I have not built a 383 before, only raised blocks.