Battling overheating new 360 build

-
DSMRossi

DSMRossi

Well-Known Member
Joined
Mar 15, 2016
Messages
98
Reaction score
47
Location
RI
Just finished putting a rebuilt 360 in my car. The motor runs great, plugs look good, but I've been fighting an overheating issue since the motor swap that I didn't have with my 318.

When idling, the car will run all day, no problems. It's when I'm driving that the temp will work itself all the way over to the hot-side of the dummy-gauge. I have to pull over or park and within a few seconds the temp will drop back down.

I have a 22" radiator and the factory shroud. I'm not running a clutch on the fan, however I have the factory 6 blade fan installed.

One thing I did notice was that the fan was about 2 1/4" away from the radiator itself. I purchased a spacer to get it closer to 1", but I'm unsure that's going to solve my issue.

Pic of the plug, car might be running a touch lean, but nothing out of control. I am running 38 degrees all in and have the vacuum advance hooked up. Maybe I'll try running without the VA and see if a little less timing helps the issue?

I would think that a 22" radiator and shroud should be able to cool an average 360.

plug.jpg
 
What water pump are you running ?
6 vein or 8 vein ?
Thermostat ?
 
6 vein pump, therm is a 180 I believe.

That actually leads me to another question, why would the thermostat temp setting matter if it's wide open at this point anyhow? I've seen people say how running a lower temp therm will help cooling issues, but I don't see how considering the thermostat is open whether it's a 160 or a 190 when you're running 200+ temps.
 
DSMRossi said:
6 vein pump, therm is a 180 I believe.

That actually leads me to another question, why would the thermostat temp setting matter if it's wide open at this point anyhow? I've seen people say how running a lower temp therm will help cooling issues, but I don't see how considering the thermostat is open whether it's a 160 or a 190 when you're running 200+ temps.
Click to expand...

You are running a pump for an a/c car. Unless you have an a/c car, with an a/c upper pulley, you are running the wrong pump.
Start with changing it out for an 8 vein.

In regards to the thermostat. A 160 will open quicker than a 180, circulating water quicker. In most circumstances, a 180 will be fine.
I like the high flow Milodon thermostat.

Start with the pump.
Also back your timming down to 34 all in.
 
Back off the timing to 34*. Get a temp gun and read the upper and lower hoses, you should have around 10* drop if the radiator is good.
 
I think I have a 6 vein off the 318 that I can swap on and see if it changes.

My concern with backing my timing off is how am I supposed to tune the car for peak performance? I have no detonation now, which means I can probably run a few more degrees on pump gas and squeek a bit more power out of the new motor.
 
shroud should cover around 2/3 of the blade and have just enough room at the end of the blades to get the v belt through make sure there is no place sucking air at the shroud to radiator
 
DSMRossi said:
I think I have a 6 vein off the 318 that I can swap on and see if it changes.

My concern with backing my timing off is how am I supposed to tune the car for peak performance? I have no detonation now, which means I can probably run a few more degrees on pump gas and squeek a bit more power out of the new motor.
Click to expand...
If you back off on the timing and your heating problems goes away then you have an idea on what could be causing the problem. You can always move the timing back, right?? One step at a time.
 
If you're changing pumps anyway, you may want to go with a flowkooler. Switching to an overdrive pulley setup and a clutch fan may help, but a steady build up of heat is usually a lean condition and/or over advanced timing.
 
Does your lower radiator hose have a spring in it to keep it from collapsing?

Did you have the radiator rodded out?
 
DSMRossi said:
I think I have a 6 vein off the 318 that I can swap on and see if it changes.
Click to expand...
You mean 8 vane.
You want an 8 vane pump.
Also, if your going through all this, why not put on a new or rebuilt pump ? They are generally, not a lot of money.
 
Last edited:
38 degrees total sounds like a worn out stock motor .lol

Try 35, but really before that get the fan within 1.50 from the radiator and have a NEW RADIATOR CAP.
 
mderoy340 said:
Back off the timing to 34*. Get a temp gun and read the upper and lower hoses, you should have around 10* drop if the radiator is good.
Click to expand...

I'll bring it back to 34, however this is part-throttle driving on backroads ~40-65 mph where I'm having the problem, I'm not all in anyhow. Maybe I'm getting too much from the vacuum advance?

dodge71demon said:
shroud should cover around 2/3 of the blade and have just enough room at the end of the blades to get the v belt through make sure there is no place sucking air at the shroud to radiator
Click to expand...

I definately don't have that. I have maybe 1/3 covered and the fan 2 1/4" away from the rad. The new spacer should bring me 1 1/4" away and cover more of the fan. I don't think I'll buy any parts until I test this out
 
Just a thought. I have a 360 in my 66 cuda and it’s always ran warmer than the 273 that was in it before. Perhaps 360s run hotter than the smaller engines.
 
Sreyno said:
Just a thought. I have a 360 in my 66 cuda and it’s always ran warmer than the 273 that was in it before. Perhaps 360s run hotter than the smaller engines.
Click to expand...
Could be - I'm .030 over and also zero decked the block so my compression is up there as well. While I know I'm not detonating, I'm beginning to think I just have a hot running motor and need a more efficient cooling system. How hot do you run on average?
 
MOPAROFFICIAL said:
38 degrees total sounds like a worn out stock motor .lol

Try 35, but really before that get the fan within 1.50 from the radiator and have a NEW RADIATOR CAP.
Click to expand...

I've always tuned for max timing advance until detonation, then backed off. Once I find peak timing, I adjust the rest of the curve for best performance. I've never had cooling issued like this though. I find that a lot of people simply set peak timing for a generic number regardless of their setup and call it good, which leaves power on the table.
 
DSMRossi said:
Could be - I'm .030 over and also zero decked the block so my compression is up there as well. While I know I'm not detonating, I'm beginning to think I just have a hot running motor and need a more efficient cooling system. How hot do you run on average?
Click to expand...

I would also suggest putting in a real temp gauge so you no exactly what you are running temp wise. Its a 40+ year old temp gauge after all.
 
If you can idle without problems, Once you are driving more than 25mph, you can eliminate the fan, shroud and clutch from the equation because you are getting more airflow than those components can generate when at those speeds.

I'd also look at water pump pulley to crank ratio. Make sure you overdrive the wp pulley
make sure the temp gauge is accurate
 
Ccas said:
If you can idle without problems, Once you are driving more than 25mph, you can eliminate the fan, shroud and clutch from the equation because you are getting more airflow than those components can generate when at those speeds.

I'd also look at water pump pulley to crank ratio. Make sure you overdrive the wp pulley
make sure the temp gauge is accurate
Click to expand...


I didn't really consider that. The car only gets hot under load, so yes above 25mph. I could be in bumper to bumper traffic or sitting idling in a parking lot and not have a problem.

Car currently has what I believe to be the OEM pulley that slides over the water pump shaft.
 
Ccas said:
If you can idle without problems, Once you are driving more than 25mph, you can eliminate the fan, shroud and clutch from the equation because you are getting more airflow than those components can generate when at those speeds.

I'd also look at water pump pulley to crank ratio. Make sure you overdrive the wp pulley
make sure the temp gauge is accurate
Click to expand...

Most complain about idle and low speed overheating. Check this ^^^^ and make sure the lower hose is not collapsing.
Also understand your total timing and If using vacuum advance how that effects your cruise timing number. High flow 180-185 stat should help.
 
DSMRossi said:
Car currently has what I believe to be the OEM pulley that slides over the water pump shaft.
Click to expand...
Just measure it and then measure the crank pulley. You might want to switch to an AC WP pulley
 
Johnny Dart said:
You mean 8 vein.
You want an 8 vein pump.
Also, if your going through all this, why not put on a new or rebuilt pump ? They are generally, not a lot of money.
Click to expand...
I've also seen a lot of these rebuilt wp built with stamped impellers instead of cast impellers. The stamped ones appear like they would move a lot more fluid but they are bad news. They create a lot of cavitation.
 
You must log in or register to reply here.
-

Back
Top