just swapped complete engines and went from a 305 TBI to a 355 TPI, now I'm running temps of 220-240 degrees.
both fans kick on at about 220.
new sensors all around.
I have a 160 stat in now.
My 305 ran at about 180....which was great, I'm no to happy about the 220+.

question in my mind is are the radiators the same?

thanks

 

new water pump on the new block?

 

The primary fan is controlled by the ecm, 220 sounds about right, you can change it but you'll have to burn a new chip to do so. also , bear in mind, those gages aren't dead nuts perfect, The gage in my 86 camaro showed 10 deg higher than the temp actually was.
The secondary fan should be controlled by the switch in the pass side head
I think that is set for about 240.
Sounds like you have both fans wired to the ecm, it shouldn't hurt any thing like that.

 

yes it is a new pump "Tuff Stuff"

 

from what Ive read you can buy a new temp sensor for the fan turn on (side of the driver side head on my 305) and you shouldnt have to reprogram your ecu. All of them come factory equipped to turn on at @220 for the primary and @240 for the secondary.Im not totally sure but there are alot,alot of old posts on running cooler temps . should be all there. good luck with the new motor.

 

question, can the under drive crank pulley cause higher temps

 

I Put The Fan switch to The Water Pump Work Great See attachment
1991 z28 camaro 305 tpi