Rough cylinder walls, What can be the cause? Options

[HansJan]

Hello,

Today the shop had taken the engine out of the car, just to replace the very stiff valve springs. When the heads came off we noticed that there are rough areas on the cylinder walls. Not everywhere, but at least two areas per cylinder.

FYI:
Cylinders are 103.8 mm (by AA).
Pistons are also by AA.
Markings on cam: CWC
Valves Intake: 44.35 mm
Valve Exhaust: 38 mm

My question to the brain-trust is:
What could be the cause for the rough areas?

Some back ground info:
This car supposed to have "Nickies" Cylinders and JE-Pistons.
Obviously the (Craigslist) seller and I are no friends.
After receiving it, I drove the car for less then 10 minutes before the car caught on fire.

[McMark]

I can see from the cylinder fins that those marks are on the top or bottom. I'm guessing the top since the bottom usually has oil leaking out of it.

My WAG (wild ass guess) is that it's something to do with the rings chattering or piston rock. 104 pistons aren't really reliable. Did you measure the stroke? An engine that uses 104s has to have a lot of other engine components upgraded to do right. If the rest of the components aren't right things like piston speed and rod ratio can cause problems.

Building a 104 engine right will cost as much or more than buying a 911 engine, but won't be nearly as reliable or powerful. Check over the rest of the components, but if I were you I would plan on installing new 96mm pistons and cylinders.

[worn]

I can see from the cylinder fins that those marks are on the top or bottom. I'm guessing the top since the bottom usually has oil leaking out of it.

My WAG (wild ass guess) is that it's something to do with the rings chattering or piston rock. 104 pistons aren't really reliable. Did you measure the stroke? An engine that uses 104s has to have a lot of other engine components upgraded to do right. If the rest of the components aren't right things like piston speed and rod ratio can cause problems.

Building a 104 engine right will cost as much or more than buying a 911 engine, but won't be nearly as reliable or powerful. Check over the rest of the components, but if I were you I would plan on installing new 96mm pistons and cylinders.

I cannot see piston velocity changing since that is RPM given constant rod length. It is gonna be more over square fear sure. What else needs to be done to make things work? Love to learn from you guys.