340 runs hot

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Neal Zimmerman

Neal Zimmerman

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Springfield Oregon
Hi, newer guy here. I just bought my 68 barracuda yesterday. The drive home was a disaster that ended with a tow truck because I didn't want to destroy the motor ( 340 small block , 10 to 1 pistons, very mild cam, premium gas) First thing I notice is lots of pinging followed soon thereafter by a hot temp gauge and poor power. After twenty miles I pulled over and called the tow truck. Radiator just about blew the top hose ( tennis ball sized lump) and there is no way I could have gone much farther. Here's my ideas but i don't know much, hoping for some more experienced ideas. Timing too far advanced? plugged radiator? Has a new Edelbrock carburetor and its not set up properly? This car has not seen serious road use for 15 years, just weekly fire ups to move it around the property and keep the blood flowing, and yes it was premium gas in it. I filled the tank on my way out of town.
Thanks in advance, Neal Zimmerman
 
I would have the radiator rodded out and cleaned, replace all the hoses and then see what it does. Without knowing the condition of everything, you need to start with the basics. And yes set the timing. Oh yeah and welcome to the best A-body site on the net.
 
If the hose didn't pop then there is still an overheat problem.
Myself I would start with new hoses (bottom one with the spring in it), then go after the thermostat.
If that checked out it would be block and radiator flush time, then go on from there if needed.
All kinds of crap collects in the engine when they sit.
 
you were going to put ALL new hoses on it, flush the system and put a new T-stat in there anyway - - right!?
 
Had you checked the coolant level before trip?

Is it possible the coolant was low to begin with, and just overheated from lack of coolant?

Was an empty system filled, then not run, and thus not "burped" allowing for low coolant level?

If you're sure coolant level was up. Then check for a stuck thermostat. Replace with a "Fail OPEN" cap, to avoid the tow truck thing.

cheers
 
inertia said:
Had you checked the coolant level before trip?

Is it possible the coolant was low to begin with, and just overheated from lack of coolant?

Was an empty system filled, then not run, and thus not "burped" allowing for low coolant level?

If you're sure coolant level was up. Then check for a stuck thermostat. Replace with a "Fail OPEN" thermostat, to avoid the tow truck thing.

cheers
Click to expand...

Fixed it fer ya. :D
 
do a quick check on thermostat. Put it in a pan of water on the stove , heat untill hard boil, watch to see when it opens. A candy thermometer used in conjunction is very helpful to determine exact opening temperature. My 72 340 with 185' thermostat , 200 miles on rebuild, new thermostat , heated badly within 2 miles. On test it did not open untill the pan was boiling hard, replaced it and it ran normally. I do not have a fan shroud.
Yote
 
I would dial in the timing first
get rid of that pinging

get the carb dialed in
 
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