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New create 350 overheating

3K views 13 replies 10 participants last post by  AutoGear 
#1 ·
I have a 1934 Master resto rod with a GM create 350 edelbrock intake and carb. shorty headers hei distributor everything else stock. Starts and idles great drives great as well but when you get it out on the highway the temp will start to creep up from 180-215 and up if I don't pull over. It has a new 3600 cfm electric fan and a new Manufacturer's Part Number:1-181DF-AXX Afco rat rod radiator new water pump base timing at 10 degrees.

I've tried 4 different thermostats 160-180 and running without it still over a period of time will start running hot on the highway. I just replaced the water pump again just to try a new one no luck.

The only couple of things I have left is the radiator is either to small or the auto meter electric temp gauge is reading incorrect.

Other information flushed the cooling system several time
fan shroud covers the whole radiator
fuel pressure looks great 5.5
carb doesn't smell to rich or lean
plugs look good
oil looks good
engine idles smooth not missing
starts on first hit

Thank you for any help
 
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#2 ·
What color is the flushed coolant? Why so many times? brown in color.

Did you retorque stuff after the breakin haet cycle...

Is there drips or a sweetness smell to indicate the coolant system is not able to keep pressure? Try to pressure test the cooling system with dye if that is suspect.
 
#3 ·
Are you losing coolant? Does it get too hot idleing as well or just going down the road? If Idle is fine, and the problem only exist going down the road it is an airflow problem, you're not getting enough air through the radiator. Most shrouds will have vents with flexible flaps over them that will allow more airflow when in motion and still seal off and allow the fan to do its job when setting still. You could try removing the shroud if it can be done without an excessive amount of work, and take it for a drive to see if that helps.

Kelly
 
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#10 ·
but when you get it out on the highway the temp will start to creep up from 180-215 and up if I don't pull over.
If it cools in town, but not on the freeway, that tells me that there is insufficient area for the hot air to escape the engine compartment. Space the rear of the hood up by one inch with wooden spacers and see if the problem goes away. If so, then you could do some surgery on the inner panels and fix the problem. Also, please stop fartin' around with low temp thermostats. Use a Milodon performance thermostat. Choose a 190-195 unit so that the motor can run at optimum efficiency.
Performance Water Pumps From Milodon

The last thing is to use a spring in the lower radiator hose to prevent it collapsing at highway speeds.
 
#13 ·
Sorry for the late response guys and thank you for all the input. I've been chasing my tail with this thing for the last few weeks so I took the weekend off from it spent it with the better half. The core area of the radiator is 16 by 22 it would seen to be enough surface area to handle this create motor but I'm no expert.

I can't bring the shroud out any further due to clearance issues with the short snout water pump. I can't switch to electro fan to the front side of the radiator due to the condenser clearance. I did back flush the cooling system several in hopes to find a clog but water is clear and has great flow.

Tomorrow its back to the basic's checking the carb and engine timing with another set of eye's and tools. I'm going to check the float levels in the carb. and idle air screws. In addition have a buddy bring another timing light over and retime the engine together.

I'm going to start by adding a couple degrees of timing after verifying the current timing with a known good timing light. Just to see if any difference is noted. Any other suggestions you guys have would be a great help and I truly appreciate your help.
 
#14 ·
*Is your radiator a 2 or 3 core radiator?
*Can you add an "anti cavitation plate" to your waterpump?
*How much space is between your radiator and your fan assembly?
*Is your waterpump the correct rotation for your setup?
*Are you using those stupid "underdrive" pulleys?
*Use at least a 185* thermostat and the proper cap for your system.
*Are you using the proper mixture of coolant and clean water?
*If you know someone with an infrared thermometer, after the car is hot; take temps from the top, middle and bottom of the radiator.
*Please don't use those convoluted radiator hoses; use a proper premolded hose with good clamps and a spring in the lower hose.
 
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