Thanks to NOSbeast for input. Have run it with out therostate , no help.I pulled water pump all is good and thight there, no leaks or slop in the shaft. Radiator flow though checked before install. The fan is NOT backwards either can feel the pull on front of radiator.Still need to try (54TOW) idea about small hole in theromstate. Keep up the thinking guys I can't rebuild this is I can't run it.
I've been reading your post with interest. You said that the first time you drove it, there were no overheating problems. But then after throwing the proverbial kitchen sink in it, the new gauge consistently reads on the hot side.
While it's always helpful to have the right radiator cap I don't think that is your problem. A small hole in the thermostat is good to "burp" the air out, but since you say it runs hot even without the thermostat installed, then the thermostat isn't your problem either. It seems to me that you may have a bad gauge or sending unit instead. It's difficult to check a gauge or sending unit for accuracy; grounding it only confirms that your gauge reads over the extreme range. Chevrolet used to provide specs for gauges so that a technician could bench test instruments, but I don't know where you would find them. The equipment cost would probably be prohibitive if you don't already have the tools.
If the old units seemed to work ok, and you still have them, you might try swapping out the sender first and see what it reads. If it's normal you know it was the sender. If not, then you could use jumpers to hook up the old gauge and see how it reads, likewise if it reads normal, you've found your culprit, or at least verified them as much as possible.
Aside from that, you might consider purchasing a new gauge like used on generic applicatons to use for test purposes.
