I took one of the heads off my seized 360 last night, and in the process of cleaning out the lifter valley, noticed an X cast into the block. I understand that this indicates a higher nickel content in the casting - is that correct? Is there anything special about having a "high nickel content" block?

The head gasket didn't look to be blown anywhere, so that's good, and I cannot feel any ridge at the top of the cylinder, which I find intriguing - maybe I'm just not experienced enough to detect it.

The valves are covered with dried oil and possibly carbon, the motor has been sitting for so long (25 years?) that I cannot get a read on what their condition is - but it looks to me like there are 2 sets of springs on the valves - the inner set look like the are made of flat stock that has been coiled. Is that a stock setup?

The cylinders have been soaking in penetrating oil for about a month with no movement so far. I have the motor turned on the stand so that the uncovered pistons are pointing straight up, and I have laid plastic over them in an effort to keep the penetrant from evaporating. I will probably wait another couple of weeks before I rotate it around and take the other head off. If the penetrant doesn't work after that, I will start taking the bottom out of the thing and see if I can free the pistons from the bottom. Anyone have any advice about that plan?

My last 360 block question is: how come all the blocks on ebay are "390" blocks and not "360" blocks when they are exactly the same?

 

So what are your plans for this motor? If I was going to rebuild it I'd knock those pistons out and plan for a rebore. Use a rubber mallet and something soft like wood or brass to push out the pistons. Do this with the crank disconnected from the rods, is motor this still in the truck? If the motor is seized then your going to have to pull it, it's real easy. If you scoured the hell out of your cylinders it would most likely be cheaper to get a block from a scrap yard and go from there. I think all scrap yards will call the 360 a 390, so beware.
My heads looked like garbage too when I took them off, but when I sent them to the machine shop and had them reworked, everything was OK, I just had to have the valves and seats reground so it stayed cheap. Your springs sound stock, nothing unusual.

 

What kind of penetrant are you using? I would suggest brake fluid. That stuff will get into everything, and you get a lot of it for your money. You might also try flipping it over 180 degrees and letting the penetrant soak from the other side for a while.

I learned in shop class that the wood end of a claw hammer works good for disloging pistons. I'd just pull the other head, remove the crank, and start taking the piston and rod assemblies out.

If you cannot feel a ridge, you're probably OK just re-honing it. That is if there aren't rust pits in it! Hit it with the hone once and you'll find out right away if it's pitted.

The reason they're all called 390 blocks is so they can get higher bids from uninformed people!

 

I have no big plans for this motor. It came out of a parts truck that I bought on Ebay, and had delivered for $127. I've already sold enough parts of it to break even, so everything I have left are free parts. The motor is on a stand in the garage.

I have no knowlege of the truck's history except that it still has license plates dated 1978 on the bumpers, and the previous owner bought it with a group of other vehicles that had been sitting "in the timber". The body was fairly rust free, so I'm guessing it was parked in the woods when it was 10 years old - why, I don't know. I am really just playing and learning with this motor. If the parts are good, I might build it and put it in one of my other trucks. It's kind of nice to have an extra motor to just "plink around" with. It has that same heads as my other two motors (C8AE-H).

I'm using Gibbs penetrating oil - saw it on the web - it's supposed to be the hot stuff - but so far, I have not seen any results. In fairness to Gibbs, the pistons could well have been siezed due to overheating or loss of oil. I won't know untill I get them to move or beat them out and examine the cylinder walls. The three cylinders I can see now look to be ok as far as not being scored.