Normal Operating Temperature?

[1966-300]

Hello again to all. After installing my rebuilt 383 in my 66-300 it took quite a while before I could get her started. Bad starter relay, fuel pump among other of murphys gremlins conspired against me but today was the day she finally fired. I let her run at the suggested RPM range to break in the cam and the POR paint I used on the manifolds seemed to burn in nicely. Now my question is this. What is the normal operating temperature for the 383? The car initially had only an idiot light but I opted for a temp gauge insted of the light. For todays running it keept creeping until around 230 then seemed to stay there. No coolant leaks and am just using standard pre mixed 50/50 anti freeze. I am just curious what a normal temp range can be expected.

 

[commando1]

It should operate at the thermostat rating. If you have a 180, then that's what it will operate at.



Theoretically....

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[1966-300]

Thanks Commando. But I thought the 180 deg thermostat was simply the opening point where it would circulate, not necessarialy the operating temperature at the temp sensor. But I defer to your greater knowledge, and now must try to figure out why I am running so hot. I was concerned when building the engine as the head gaskets that were in my kit and all others I could find for that matter had much smaller cooling passages that had me concerned until they guy at FelPro basiclly told me not to worry it was re engineered that way.

 

[commando1]

I don't think it's the gaskets either. Did you acid dip the block to totally clean out the coolant jackets?
FWIW, The thermostat is constantly opening and closing to maintain the temperature. Just like the thermostat in your house. If set at 72, the furnace goes on at 71 and shuts off at 73. You are "maintaining" the temp at 72.
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[1966-300]

Yes sir block was dipped, and was exceptionally clean, I dont think thats the issue. When I pulled the engine the radiator was shot I could not even get it recored it was beyond help. I ordered a new one from Rock Auto and the item that came looked to be an exact replacement in all respects. Shroud fit perfectly, trans cooler everything. I have not been able to do much the last few days because we have been getting flood type rains so I have not had it running since the first start. The timing is certainly off and the first time I got it running I had the RPM's up pretty good for 20 minutes or so that may have contributed to the higher temps a bit. I plan on getting the timing right and actually driving it next chance I get that should create a bit more cooling effect. At least I hope so. Thank You so much for all your input it helps alot.

 

[commando1]

You're more than welcome.
But you call me "sir" one more time, I'll have to slap you upside the head.

Just as a starting pointing to troubleshooting the situation:
Do you have a 22" or 26" radiator?

 

[1978 NYB]

But you call me "sir" one more time, I'll have to slap you upside the head.

Roger that... Stan worked for a living.

 

[rexus31]

Make sure your timing is set right, test your radiator cap to make sure it can hold 16 lbs of pressure and make sure your clutch fan has a little drag to it when moving it by hand (assuming you have a clutch fan). Despite the opinion in this thread, an engine equipped with a 180* thermostat will not run at 180*. Generally, an engine will run 5-15* above the temperature rating of the thermostat. I run a 180* thermostat in my 383 and, depending on ambient temps, runs anywhere from 180-190* in our mild So Cal winters to 185-195* during the summer months. When do you notice the temp creeps up? Highway or city driving?

 

[1966-300]

Thanks Rex. I was under the same impression that 180 was the T stat spec and an engine would typically run 5-15 deg hotter. I have yet to actually drive the car, and do need to get the timing right. I am not sure I even have a problem just the temp climbed during the cam burn in. We have had some heavy flooding here this week, but hope to work on it more this weekend. Thanks to all and Stan I wont call you sir again, I too worked for a living career Navy Enlisted I should know better.

 

[rexus31]

No problem. Also keep in mind a fresh motor will run hotter than normal until everything loosens up a bit. Good luck!

 

[1966-300]

Thanks to ALL. Had her running this weekend and took her out for her first drive since the rebuild. Everything seemed to be good, and after getting it timed rght the temp held steady at 190, for a good hour, even parked it and left it running 15 or so minutes stayed steady 190. Thanks again to all. My next question will be about the best carb to install. Thanks Again

 

[BillGrissom]

It will not run at a constant temperature. The coolant temperature increases as the cooling load increases. The thermostat does not cycle open and shut like the on-off control of the thermostat in your home. It is a "proportional controller", which does not regulate exactly at the "setpoint", but rather shows "proportional droop" (or "offset") as the load changes. For more info, search those terms. 190 F is about perfect. I prefer a 195 F thermostat. You get better mileage and less engine wear at higher temp, assuming it doesn't overheat.

Re carb, depends on what you want out of the car. For drag racing, a Holley double pumper. For a driver where you care about mileage, a Holley vacuum secondary is claimed good. The very common Edelbrock 1406 is simple and reliable. Holley made the "Economizer" after-market line in the late 70's to early 80's. A spreadbore - Thermoquad or Quadrajet is good for both performance and power, but good ones are now rare. Your carb should match your intake manifold. I have an interesting Offy Dual Port intake for my 383 I haven't tried yet. It has small runners for the primaries and larger runners for the secondaries.

 

[livininharrow]

It will not run at a constant temperature. The coolant temperature increases as the cooling load increases. The thermostat does not cycle open and shut like the on-off control of the thermostat in your home. It is a "proportional controller", which does not regulate exactly at the "setpoint", but rather shows "proportional droop" (or "offset") as the load changes. For more info, search those terms. 190 F is about perfect. I prefer a 195 F thermostat. You get better mileage and less engine wear at higher temp, assuming it doesn't overheat.

Re carb, depends on what you want out of the car. For drag racing, a Holley double pumper. For a driver where you care about mileage, a Holley vacuum secondary is claimed good. The very common Edelbrock 1406 is simple and reliable. Holley made the "Economizer" after-market line in the late 70's to early 80's. A spreadbore - Thermoquad or Quadrajet is good for both performance and power, but good ones are now rare. Your carb should match your intake manifold. I have an interesting Offy Dual Port intake for my 383 I haven't tried yet. It has small runners for the primaries and larger runners for the secondaries.

absolutely correct regarding higher engine temps resulting in less engine wear and better mileage. never us a tstat lower than 190. if your engine requires a lower one than you have cooling issues not related to a tsat. jmop

 

[1978 NYB]

I have a 1406 carb on an Eddie mainfold.

 

[1978 NYB]

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