I already posted this question in a german froum, but I'd like to get more opinions on that topic

it's about an original 914-6, which got a complete enigne rebuilt (incl. new cylinders, pistons chains, ...) 20 years ago
then the owner drove it for about 3k miles within the next 7 years
from 1994 on, the car was stored away and never started again ...

so, how to awake this engine correctly, to avoid and long term damage
some told me there might be problems with the carbs, probably any rust inside the cylinders and bearings and, and, and ...

any comments appreceated

Gustl

The bottom end should be good if the oil was changed shortly before the long sleep. I'd be taking the heads off to check the cylinders at least. Full carb rebuild.

Yep on the above.

I would also put some oil down the cylinders and rotate by hand.

Going thru the same thing with a /6 conversion that was parked 20 years ago (1990).

Pull tank and flush .... change filter sock

Blow fuel lines clear

Change fuel lines

Change filter and fuel pump

Rebuild carbs

Pull sparkplugs

Squirt penetrant and/or oil in cylinders

Rotate engine ... if frozen, fill cylinders with diesel fuel and let sit for 3 - 5 days and try again.

Change oil and filter

Set static timing with new points/condenser

Let 'er rip

Got my fingers crossed that the one I'm working on will fire. Have already turned engine over with no problems. Got one sparkplug that didn't want to move ... won't force it .... will hopefully fire engine and heat it up ... after cooling will see if it will move.

My opinion only ... others will vary

Depending on the model (T, E, S) and the average local humidity, you may have to kiss it good-bye. I had a frozen 2.4T that I bought for the MFI. The pistons were literally fused to the cylinders.

I ended up taking a sledge hammer to it just for fun (mag case had water rot) and bits and pieces of cylinder came off still stuck to bits and pieces of piston... seriously.

Alloy pistons with steel cylinders don't make for good bed partners, especially when the snooze is a Rumpelstiltskin one.

Lots of good advice here already.
If the rings are stuck to the cylinders, take your time trying to break it free. Rather than one mighty blow, rock it gently back and forth, add more penetrating oil to the cylinders, rock it some more. It might take 2 days. There's no point in breaking the ring lands off of the pistons.

I also would like to chime in with my past use of PB blaster on hibernated engines.

Spray, let sit and turnover by hand, repeat. Change the Earl and follow the Slits and others suggestions above. The PO of the engine I run today. Just left the car outside in the rain, snow and sun for eight years after it quit for FI issues. True it was just rebuilt before it quit. Long story short. I can tell you that it still runs strong today, has great compression and runs great.