Help with overheating!

[xlr8or]

Sorry I know this isn't really bowtie country but was looking for some suggestions on where to look.
I just put a new set of heads and intake on my Chevy 350 motor. Now when I run it the temp goes up to 230 by the time I went down the street and back. I pulled the radiator cap and there was pressure but the water wasn't hot....... So do you think it's just the new thermostat not opening? The heater lines are nice and warm as is the lower radiator hose but the upper didn't seem very warm to me. Now I know for sure the head gaskets are the in correctly I must have checked them six times each before putting the head on and the water pump was never taken off the block and was working fine.

I just wanted to get any other ideas before wasted $100 worth of gaskets.

Do aluminum heads require any different thermostat range.
How about the temp sensor? It is a mechanical unit that was hooked directly into the old iron head and is new head now?

Thanks for any ideas.

[Bob Putnam]

It's most likely the thermostat - either stuck or installed backward. I would pull the thermostat out completely as (a temporary test only) to check for water flow. The car should be driveable without the thermostat for slow speeds only.

[Mike I]

xlr8or,

I'm not disputing Bob's recommendation. By all means check the thermostat first, it's certainly the most likely cause and the simplest thing to fix. My first impression when I read that you installed the new heads and intake on your motor is that you may have installed late model parts from an LT-1 with the reverse flow cooling design. They would require the special reverse flow pump and drive system to work properly. Just a guess in case the thermo is not the problem. Good luck.

Mike

[xlr8or]

Thanks Bob. I'll try the thermostat first.

Mike, the heads are Edelbrock 60899 performer RPM heads for 262-400 up to 1986 so they are correct.
One thing that did bother me though was the fact that the felpro gaskets had such small coolant holes between the center cylinders. Edelbrock and felpro said that was ok and was there to even out hot spots the center cylinders.

I'll pull the thermostat this morning and try another one.

Thanks for the input guys.

Heck I was just trying to take it to the muffler shop. Guess I'll have to drive it on open headers one more time for the neighbors.

[xlr8or]

Well I boiled the thermostat and it didn't even open at 200+ degrees. Put in a 160 and it's running at 180...
Perfect.