i'm in the process of building a 355 ci and i brock the sensor in the passanger side head. does this need to be changed to a 350 and what is and a part # please...it's above the knock sensor

 

That is what they call the coolant fan switch. Did it look like this?:


Pretty much everybody breaks it at some point or another. If you were in the states you could just order an aftermarket lower temp. fan switch (Hypertech and Jet sell them) from a place like Summit Racing or Jegs. Not sure if they're available in Germany or not. Let me see if I can dig up some part numbers.



EDIT: Here's some part numbers I found for a stock replacement fan switch:

AC Delco part number: 154315
GM part number: 88961770

If you need more part numbers, just let me know.

 

Yeah, you need to replace it. It's the only thing that turns the (single) cooling fan on in a TBI car, unless you turn the A/C on.

While you're at it you might want to upgrade to an aftermarket one with a lower fan turn-on temperature. Stock ones don't turn on until more than 220* or so. Might want to get one that clicks on down closer to 200, or whatever will work with your thermostat temperature without running the fan constantly.

 

GM# 3053190 will get you a 203F fan switch.

 

it's the one in the other head that one is on the driver side of car this on is on the pass side. it looks like the knock sensor but on the head. i was disabled in the army and know i'm back home in alabama...

 

The sensor that Benm posted should be in the passenger side head. It should be very close to the exhaust maniofld as pictured here,
Note that the temp sensor in tis pic is broken as well. The mushroom part of it has broken off.