new 392 blows steam out exhaust

chip nimmons said:
3-4 minutes and then it stays there.
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That indicates that it is staying at the ts opening temp.

One good test is to start it up cold and let it warm up while you monitor the inlet to the radiator tank and top radiator hose. The moment you feel it get quickly hotter that is your ts opening point. Don't miss interpret the gradual warming. Actually the entire hot tank will get considerably hotter in an instant soon as the ts opens. Mark that point on your gauge as such. Will most likely run slightly above that point on the highway.
 
Ok, update: I ordered a correct 160 thermostat from IHOnly north. Installed that over the weekend and I found this radiator cap with a thermometer in it. Burped the system a little and took it for a ride. The gauge reads a little lower now. The gauge at the radiator cap reads 140-160 max. I'm thinking now that the gauge or sender is out of spec. Since the gauge worked ok with the old engine I'm starting with the sender. I still want to borrow a friend's ir themometer but haven't yet. After driving about 7 miles I can put my hand on the thermostat housing. It's warm but I can hold it there for a minute give or take without scalding my hand. It feels the same temp as the top of the radiator. Any thoughts from the gurus?
 

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That is totally normal. These are designed to run wot for hours in hot weather so 7 miles and 140 - 160 is expected. Pull a decent hill, jump out and see the temp. Should be at 160 +. That indicated the ts has consistently opened. The cooling system has some normal leakage past the ts so unless it is loaded the ts opening temp May not be reached.

I would also expect the engine temp to drop below 160 on long down hill drives.
 
I thought your question regarding cause was in the context of the last sentence about the low radiator temp and why the ts housing was not super hot. Was I mistaken, most likely.:frown2:
 
Stop tormenting yourself over this, the stock guage is crap, just an indication of proper function, if you are really concerned pick up a new guage at one of the parts store for a few bucks and plug it in, then you will know for sure, no more doubts. Then if you want you can plug the old one back in if you want to keep the stock look. I prefere guages that show actual temperature and pressure readings, not the garbage that has a couple of lines on it. :thumbsup:
 
Good advice steve. I know I'm pissing with this, the first time I ran the new engine it blew the head gasket and I'm paranoid about it.
 
I agree w/steve.don't rely on the dash gauge.get a good 1 an install it where you can see it good.when I rebuilt my 392,and about $3000.00 + dollars you want good insurance.get a good gauge on it.it'll pay for itself.Jeff:yawn:also goe's for the oil pressure gauge as well.
 
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Been busy but the gauge can be as reliable as any electric temp gauge. Two variables to worry about.

1 ) the constant voltage regulator. It feeds an effective (rms) 5-6 volt dc pulsing voltage to the gauge. If it is high you will see a high scaled reading.

2) the variable resistance sender. Could have been swaped out somewhere along the way with an improper one. Sorry I don't know the intended oem resistance for the correct sender but sure some one can look it up.. Then you can test it @ 212f (100c) in boiling water and at a cold temp as called out in a spec manual. If you plot the resistance to temp curve on graph paper it should be a straight line inverse t to r but on a known path. Shifted to high or to low and the gauge will read in error.
 
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