Suggestions for stuck pistons on a motor that set for years.

[NXBOY]

Just bought a complete take out 460 Dove headed with dove-c block with Boss bulkheads and it was supposed to have ran when he got it before it set a few yrs. in big building not heated with the carb off. I would like to see If I could free it up without taking apart (pulling crank) and driving pistons out. Don't want to chance cracking cylinders in a sought after block. I was thinking ATF and Acetone 50/50 mix. Alot like mystery oil. Don't mind waiting a month to see if it will free up. Will be putting a cheater bar on crank bolt and a 30 lbs weight and leaving it on. Any other Idea appreciated. P.S motor won't turn one fraction, have found in pass that usually means multiple pistons rusted or pins corroded to pistons or both. Motor looks like its been apart in the last decade, newer head and intake gaskets and is very clean inside valve covers.

[ProPower engines]

Why not do the smart thing and carefully disassemble it.
If it is what you say it is you will be better off taking it apart to avoid the destruction of a very rare engine assembly.
A gasket set is not that much cost why would anyone take the chance

[mag2555]

If it comes down to it I have taken apart some 12 fully rust bound up junk yard motors by drilling many 1/2" and 3/4" holes in the tops of the Pistons ( cast Pistons) and then collapsing them with a big ball peen hammer and a big metal bar and never cracked a cylinder wall!
You will also need a big two handed drill to keep control of drill bits this size !

[quickd100]

I've used a block of wood about the same size as the bore and threaded rods and a Heavy flat iron. Drill the flat iron to match the threaded rods screwed into the deadbolt holes. This usually works without destroying the piston.

[DaveMcLain]

The problem is that with the heads on you can't really tell what you're up against. It takes very very little rust to lock up the engine BUT that doesn't mean that you don't have a lot of rust in one or a few cylinders. A few years ago I rebuilt a Ford HP289 that had been sitting since 1972. It took me a long time to get the engine apart and in that case some of the pistons were easy to get out after a soak with light oil while a few of them were practically welded to the cylinder.

With that said I'd say that with the engine up on an engine stand pour some light oil, Marvel, diesel fuel, Kroil etc into each cylinder and let it sit for a few days. Then try the breaker bar every day or two to see if you can suddenly get it turning, good luck.

[Newold1]

I have seen a funny fix for this. With the heads off and on an engine stand take a can or fresh liter bottle of Coke or Pepsi and pour some on top of all pistons, one side at a time. Let it sit for a day and then come back and just push the pistons out from the bottom after rod disassembly from crank. I've seen this work as it seems the mild acid in these drinks has a pretty strong affect. Not good for your teeth either!

[F-BIRD'88]

Use this stuff. or use stove oil. use lots. Give it time to work.
http://www.castlepackspower.com/index.c ... e%20Thrust

[strokersix]

How about thermal cycles? Heat and cool gently several times over time while soaking in your favorite penetrant.

I would use a radiant heater but hot water would probably work too. Bonus if it's cold outside for the cold soak portions then bring inside for warm soak.

[PackardV8]

I would like to see If I could free it up without taking apart (pulling crank) and driving pistons out. . . . . Will be putting a cheater bar on crank bolt and a 30 lbs weight and leaving it on.

Definite no to trying to free a stuck engine without removing the heads. That it might work just leaves all the actual and potential problems still in there to make things worse when the engine is rotated, or worse yet, started and run. Crank bolts aren't designed to take any meaningful breaking torque. OP indicates it's a rare block which will be rebuilt, so pull the heads to assess what's there. Never hurts to loosen crank and rod bolts to squirt some penetrant in there while working on the piston/ring interface. Sometimes, it's no one place, just corrosion in many small places. After soaking each cylinder bank in turn with the recommended acetone/ATF mixture (diesel works almost as well. With on bank down and the crank up, fill the bottom of each cylinder on that side with diesel, soak, switch sides, soak.) if it still won't move, use a piece of fence post or 4x4 as close to cylinder diameter as possible. With the block sitting on the pan rails on a solid bench and secured against movement, wood held tight and straight on top of each piston in turn, a whack on the wood block with a five-pound hammer has never harmed a cylinder for us (whatever the rust damage, it was already there) and eventually loosens everything.

[Alkyfool]

Get or borrow a Digital inspection camera to take a peak what is inside through the spark plug. You might find some large spots of rust in the bore or maybe some mice made a nest or dropped seeds in there. Can also fish thru the intake to back of valve or valve covers to see some rust issue on cam, etc.

[Truckedup]

I've done a few stuck engines...Like Jack says, get the heads off....On some engines you may be able to get the crankshaft removed, it does make getting the pistons out a lot easier.. Rigging a tool like a damper puller on the block deck over the cylinder to push on the piston can save a lot of hammering if you got one stuck real bad...

[Tuner]

Mice ha ha.. in the waybach daze a pal rented a corner of the shop to do a frame-off on his '65 Corvette and chrome everything that would fit in the tank at the chrome plating shop. The bare frame and running gear, all pretty looking like a manufacturer's display, was on jack stands all completely assembled, no body, just all the machinery. The exhaust system was complete to the chrome tips. With a little effort to rig steering, throttle and brakes it could have been driven. One day he decides everything is perfect, chrome and painted, looking brand new +++ except the exhaust manifolds, they need to be porcelainized like the Jag XK-E that happened to be in the shop at that moment and gave him the inspiration. Anyhow, he removed the ram-horn manifolds and out came a stash of Corn Curls from the exhaust ports. The mice had to climb the jack stands and get in through the chrome tips to get in the exhaust system. There was at least a full bag of Corn Curls in the exhaust ports, mufflers, etc.

[NXBOY]

PART_1517036479161_IMG_20180126_143259.jpg

Cleanest used motor I've ever seen

[Bob Hollinshead]

I've used a pota-power pump on the spark plug hole with the rockers backed off and if the piston is between tdc and bdc, it will move. A grease gun can also sometimes work. This is on those occasions when you just want to try and get it running even though you know it needs a complete rebuild lol.

[DaveMcLain]

PART_1517036479161_IMG_20180126_143259.jpg
Cleanest used motor I've ever seen

I've seen old 429's look like that straight from the junk yard before. Car junk, engine perfect inside with bearings etc that look brand new.