Again, it's a 350ci/5.7l GM V8 with a carburettor and roughly 250HP and
no electronic ignition system.
Thanks in advance
Hydrostössel is most likely 'hydraulic valve lifter'. (And the word is
rather than 'soring'. Soaring is 'flying'. Soring, if we used that word
might describe how you feel if you stop soaring, and crash)
Since this happens when the engine has been running for a while, I will
it has something to do with the heat generated. Heat can cause engine loss
of power and roughness:
(1) If you begin to evaporate the gasoline in the fuel lines or carburetor.
We call this 'vapor lock'. Fuel injected systems seldom if ever
this since the high pressures tend to keep the fuel liquid. With a
the liquid pressure is less, and if the fuel boils in the line or
engine will lose power or stop. The fuel can even boil out of the
bowl, stopping the engine. If this is a problem, you may have to
adjust the carburetor , cool the fuel lines, or increase the delivery
(2) If you have an electrical part or system which malfunctions when hot.
have a very minimal electrical system here, so I would suspect any
failure would have to be in the ignition system....coil, capacitor,
module, sensor...whatever you have installed on that engine.
(3) If you lose oil pressure, and the hydraulic valve lifters cease
as they should, you can experience a loss of power, clattering of the
(4) On some of the older engines, the ignition advance curve was controlled
by vacuum from the manifold and by mechanical weights. The weights
seldom (but occasionally) gave problems. The vacuum advance system
required that the vacuum diaphragm was working properly and that you
were connected to the correct source of manifold vacuum. Sometimes it
was at the base of the carburetor, and sometimes there were more than
ports which were selected by a thermostatically controlled valve. Be
you understand the ignition system you have and that it is working to
under operating conditions.
These some of the things that have come into my mind. Maybe others will
the problem exactly and give a better answer.