running hot need some input

[DRIVEN]

I think it's safe to exclude the heater core 🙂 .

 

[ERIC87442]

Haha yeah but just thought id say

 

[JBreu]

I think that your thermostat might just be bad, or a bad temp gauge........ 8)

 

[ERIC87442]

I checked it with a temp gun

 

[88hurstolds]

I've got the same EXACT problem with a 307 and a 455, both have been rebuilt by their previous owners.
I am either suspecting the timing on the 455 or tolerances in the mains on both.
The 307 is timed by the computer, the only way for it to be to retarded is the TPS or MCS causing a rich reading by the O2 sensor. Another possibility is the Ignition Module or a bad ECM... I need to read up on this a little more.

Also, if an engine builder is setting the mains at Chevy specs the tolerances will be too tight and cause the car to run hot.
In a world where everyone sticks a Chevy in their cars it's quite possible for this to happen...

 

[Pontiac455]

Make sure the rad doesnt have a few cors plugged. When it is at operating temp shut down the engine and run yer hand down the rad from top to bottom, making sure it is the same temp. Also make sure there is not a blockage between the condensor and the rad. Make sure the fins in both are clean. Make sure ya check the clutch fan.

 

[455rocket]

This may sound nuts but make sure your fan blade isn't on backwards. I ran into this a couple times back in the day, it's something you wouldn't think and is easily overlooked.