Clean Burnt Oil Stains On Top Of Motor

I recently bought a Bonneville 2001.

The previous owner had driven it despite a problem with a vacuum cap.

The problem was easily fixed with a new vacuum cap however oil had been blown out on top of the engineblock beneath the carburators and it is now stained brown. It is burnt in.

I tried to clean it with regular car schampoo and autosol but to no avail.

Any recommendations on what to use
and maybe also what not to use?

I thought about owen cleaner but that might be to abbrasive.

Suggestions?

 

Sure, I'll snap a few pics when I get up by the garage.

 

Here comes a few picture of the brown discoloration on top of motorblock.

How to get rid of it?

 

OK, I'll check that out