Is a good idea

 

I would just look for a good used head. Too much hassle to rebuild the head.

You likely have a really bad guide and valve seat, and I can say it's likely the exhaust valve. If you remove the exhaust manifold you can take a look. A burned valve looks really beige, or off white and ashy.

 

So, I re-did the leak down test, but this time by putting oil in the bad cylinder to see if the numbers improve. It improved by around 5%. What is confusing about this is that when testing the same cylinder, the glove that I attached to the valve cover started to inflate. This would indicate a bad piston to cylinder seal, aka probably a failed ring?

The car is still drivable.

At this point, I am thinking a swap is in order. I don't think a rebuild is worth it.

Current prices for the F20c with 100k+ miles is around $5000+ lol.

 

Were the valves ever checked?

 

Not convinced a bad ring,but a valve seat

 

If the air is coming from the PCV, then you have excessive blowby past the rings.

Not sure what else would cause the crankcase to pressurize.

SOME air getting into the crankcase is obviously normal. But...if you're seeing 75% leakdown and the only place the air is going is the engine...then...

 

The valves looked flush and fine when checking with a borescope camera via the spark plug hole. I am debating on whether I should take the engine out to see the problem and just keep it in the garage to part out the good parts.

What do shops do with your old engine when they perform a swap?

 

Part it out.

 

Its your car and you need to do what you are comfortable doing But, consider pulling the head off and inspecting while you look for a motor. If the bottom end is the problem that is one thing. If its the top end then that is a whole nother kettle of fish and a swap might not be necessary. Maybe you have already reached the conclusion the bottom end is damaged.

Whatever you end up doing good luck with it and keep us all posted.