1. So what does 40 some odd years of abuse look like? Something like this. As you can see, the engine has definitely been used, and upon closer inspection it’s still the stock bore. It’s hard to say what really happened to this engine throughout its life, but one thing is obvious: A piece of metal or something got in the rear cylinder and bounced around. The head was perfectly fine, so it looks like it just impacted the aluminum piston.