Jaguar Repair: Jag 420, domestic engines, cylinder walls

Question
Hi I am working on a 420 there is 1 piston I can not move do I just keep on with penetrating oil and a bigger hammer {wood drift] or is there something else I can try and simple but what is the firing order

Answer
Hi Terry,
I take it that you have the head off since you say ONE piston you can't move? If the piston is not at the full bottom (BDC) and you have the rod cap off so you can move the crank away from the rod a little. Locate or purchase a piece of thick wall pipe that just fits into the cylinder bore. Set the piece of pipe down on top of the piston. The pistons in a 420 are flat around the top with a raised hump in the center so the piece of pipe will rest flat on the piston just above the rings. I have several times on the older Jag engines when I had one that had sat for a long time the rings will rust to the cylinder walls and stick. I then put what ever you can find on top of the piece of pipe so you can then hit the pipe in the center with a large hammer. I have broke many loose that way and several I had to first heat the piston with a torch and cool it several times and alternate hit it to brake it loose. I was even able to save most of the pistons if the cylinder walls cleaned up with a cylinder hone. If you have a deep ridge at the top of the cylinder walls it don't matter how hard you hit the piston as it needs to be bored and new pistons anyway.
Be sure to get the crank away from the rod as far as you can as you CAN'T beat on the piston with the rod against the crank as you will destroy the rod and probably never get it broke loose.

All the inline 6 cylinder engines have the same firing order 153624 and it does not mater if you start at the front like most domestic engines or the back like Jag does.
let me know how you do.
Howard