I am going crazy trying to find the problem I am having with my 305 overheating.
I changed the thermostat 180
Replaced the radiator with a new heavy duty 3 core
Replaced the water pump(can see good flow through the rad cap)
No head gasket leaks or signs of gasket trbl
Timing set at 6 btdc
This car will run at 220 temp and higher with air conditioner on after replacing all these Parts
Any sujestions?

 

is your gauge accurate and working properly.? that could be a problem as well. and check your air fuel mixture. see ifs its way out. and 180 may be to low for a small block. i always ran a 195 in my 305. because what can happen is. it opens to early and the water goes through the system to fast and does not have time to cool in the rad. try the 195. and make sure you have a good mixture of anti freeze. and make sure you dont have any air pockets in the system that could lead you to have a problem as well. let us know how it turns out.

 

I would say put a manual gauge on just to check it cause if you put all that in and have to look for more it would suck if that was your problem the whole time. Cause if you see good flow threw the rad that means the thermostat is opening. That was my first thought cause in 2 of our machines the thermostats stopped opening and caused to over heat but if you can see the water flowing and the rad is full no air pockets. I would almost have to say the gauge is not reading right. If you check and it is reading right then i would say check all the stuff like timing, air fuel mixture etc. Cause with all you fixed i don't think you have a cooling system problem that is making you over heat. Good luck and let us know what you find

 

Also maybe check the fan to. Although when your moving like highway it doesn't matter but if you only drive town etc. Maybe the fan is not working. Do you have a stock clutch fan, full time or electric. Our one dump truck was over heating and the stock fan the clutch part was shot so we put one of the full time on fans and it fixed our problem

 

Thanks Guys
I didinstall an external gauge and used a temp detector and it is correct in running hot about 220 and with the AC on can reach 230 - 240 at idle.Checked the fan and everything ok there.I have checked for air pockets.
The fuel mixture brings up something I have not checked.This does have a new rebuilt carb on it.I started 1.5 turns out and left it there and the car runs excellent with good startup and idle set at 600 rpm.
What would be a good starting point with the adjustment screws and how do you determine that you have the right mixture?
Thanks a bunch

 

If it does it at an idle i would say richen the idle pretty much and see if it still over heats. Even if it's not set perfect just to give an idea and rule some stuff out. Also what kind of fan does your car have? IS it the one with the clutch? Cause the one on our dump truck was still spinning but under a load when it needed to spin hard the clutch part wasn't grabbing . It still spun but not as good as it should of when it got hot. Theres ways to check them but im not going to tell cause most the ways i know are a good way to get killed if not done right. If it's a clutch style fan put one of the solid one that is on all the time. Check the A/F mixture first and see if thats it. You can check your plugs after it runs a while and see if they are white than your running way to lean if they are a nice light brown than A/F mix is correct.