Hey guys! New to this site and the Firebird world! I just bought an all original #'s matching '68 Firebird coupe with 79k that's been sitting in a garage unmoved since '82. Motor is seized. Just wondering if any of you can give me some ideas to try to get the motor possibly freed up before I pull it and have it rebuilt. i've heard you can try putting penetrating oils down the spark plug holes and let it sit for a few days, then try turning the crank bolt to see if it'll break free? Comments, suggestions, and idea welcome and appreciated!

Also, I have all the original owner's manuals, the little tag from the original dealer, and just found the build sheet under the back seat, plus have sent away for the PHS documents. From what I know of the history and running all the numbers and decides on my end...it appears completely original drivetrain. It only has the 350 motor in it which wasn't a very powerful engine. My question is this: when I have the motor rebuilt, if needed, does it hurt the value of the car putting superior internals in the motor for hp and torque gains as long as I keep the block a matching # block? Not looking to build a 600+ hp motor, but more than the original 260 hp or whatever the 350's were would be nice. Maybe 330-400ho range. Input?

Depends what kind of drive ability you want. 400hp may be a bit reaching for the 350 and still be able to drive it on the streets.

Yup, try the penetrating oil in the spark plug holes and let it soak. Of course leave the spark plugs out. Also, you can back off all of the rocker arm nuts, that way your not moving any valves.

I dont remember the numbers but there was an engine builder that stroked a P350 and it was very respectable.

Remove heads...

Bake in oven at 525 plus for 30 to 45 minutes...remove.

Straight Phosphoric acid in all cylinders and soak...rinse, repeat..rubber 8 to 10# mallet or soft blow hammer to free.

Rings will stick, pistons will not. Need to slowly beat pistons out from topside and rod side a little at a time.

Phos. acid will only eat rust....at the rings and any rust flash in cylinder walls.

Any advice for a motor that sat outside with no top end and the pistons are corroded solid in the cylinders?

Yard Planter

Boat anchor...

It's the numbers matching motor for my 69 goat. It will be saved.

Hole saw

Use a hole-saw to bore out the piston if everything else fails.

Post a pic of the worst hole.

Something I have always used with great success, but not on an uncovered motor yet...

Start with transmission fluid in the cylinders fill them up and let them set for at least a week. When the fluid has started to drain down past the rings, try to break the cylinders free with an extension bar on the crank. DO NOT BE TO AGGRESSIVE ON THIS - IF YOU ARE PATIENT IT WILL BREAK FREE FAIRLY EASY IF YOU GET THEM FREE, DO NOT CONTINUE TO TURN MOTOR OVER. If unsuccessful top off with more tranny fluid and wait another week, then repeat process.

When able to "break" initial rust set loose- do not continue to rotate pistons- fill cylinders up with tranny fluid again and let them set another week to drain down again. When they drain down, slightly move the pistons once more, but do not rotate them.

Fill cylinders with diesel fuel, and let them drain down at least a week. If they drain sooner GREAT fill again and wait the remainder of the week. When drained, "bump" pistons again but do not rotate.

As a final stage, fill cylinders with PB blaster or WD-40 and let it drain down for another week, if it drains down sooner- GREAT! Bump pistons again Fill and let them drain down for the remainder of the week. When pistons are free, start to rotate motor slowly back and forth with PLENTY of WD-40 as a lubricant.

Yes this takes about 3 weeks to a month- but I have always had awesome results doing this. You take the heavy fluids that are most reactive and loosen the big stuff, then go progressively thinner to remove the smaller stuff. If you rotate the pistons with the big stuff in there still, you are grinding all that rust into the cylinder walls and defeating the purpose.

Make sure you flush the oil pan out if the motor is in the car and you are going to try to start it without tearing it apart. It will smoke like crazy for a while until you burn off the residual chemicals, and the compression comes back up- its normal.

" It only has the 350 motor in it which wasn't a very powerful engine. My question is this: when I have the motor rebuilt, if needed, does it hurt the value of the car putting superior internals in the motor for hp and torque gains as long as I keep the block a matching # block? Not looking to build a 600+ hp motor, but more than the original 260 hp or whatever the 350's were would be nice. Maybe 330-400ho range. Input?"

I 'aint no expert, but...

That 350, stock, could be good for 325 HP as built at the factory (2 barrel...4 barrel?). It can fry some tires, depending on your rear end. I don't think new internals will decay the value.