1971 302 - can't get it to run cool

[Jarheadtx]

I always start here and it usually fixes the cooling issues I come across. Best part is that checking these things are free, adjusting these things are free and if you have to fix these issues it's a whole lot cheaper than throwing a ton of money at electric fans, oversized radiators, high-flow pumps etc...........

Assuming your 302 is stock so should not run hot with the stock cooling system and properly tuned motor.


Completely different "animal". Engine compartment, air flow etc....

Is 10 degrees advanced the best timing to set for a stock 302 engine?

 

[Perpendicular]

Timing is always my first question. Is the vacuum advance working? Does it curve up and increase with RPM? All things that get assumed are good. Seen a lot of base line timing set correctly, but vacuum advance not working and or frozen curve plates inside the distributor and over heating is the result.

Radiator is second. Is it an old stock unit or something new? Seen a lot of old radiators that didn’t leak, looked good, even flowed well that just weren’t up to the task anymore. The tubes were thin enough to collapse with temp and pressure.

Second the anometer test. I’m always skeptical of electric fans when they are not from an OEM application.

Thanks.

Timing is spot on.

Radiator is new

Looks like the electric fan was not doing as advertised. Installed the 6 blade flex and the truck is running cool!

 

[Perpendicular]

Did it run hot before you installed the ac, ?

No, not at all. And I am central Texas

 

[Perpendicular]

The Flex fan fixed the issue.

The truck has it's stock shroud and a 17" 6 blade fan and now runs as it should.

Thank you everyone for the insight and ideas!

 

[m_m70]

The Flex fan fixed the issue.

Awesome to hear!!

 

[m_m70]

Is 10 degrees advanced the best timing to set for a stock 302 engine?

Could be. Some like a little more, some like a little less. The thing with timing is it's just not what the timing is at idle. As Yeller mentioned, the curve and all in timing needs to be right as well. Vacuum advance and mechanical advance need to work and it's pretty simple and free to check which was what my point was. Lots of great articles/threads on this.
Glad you got it worked out.

 

[Perpendicular]

Awesome forum and support here, thanks to everyone!

Appreciate the respectful comments and ideas. So many forums do not have a community like this.

 

[Broncobowsher]

Is 10 degrees advanced the best timing to set for a stock 302 engine?

Pretty good starting point. People will often crank up the timing because they have a distributor with a crappy advance curve. To get the total advance, the crank the base timing instead of changing the advance limits (and curve). Then there is the added timing added because the carb isn't tuned and the rich mix burns slower, so more timing to make the bad carb tune feel better.

 

[joebronco73]

"Installed a high flow water pump."

Sometimes I believe I've heard others say that high flow can actually contribute to the problem. The thinking is that coolant flows through the radiator so fast there isn't adequate time for it to be cooled. But I'm no expert!

Others on here will chime in with better answers soon!

Welcome to the best Bronco site!

Norm

This can be true - basically, you'd want to do an energy calculation to determine just how cool you want your fluid; that is your temperature difference. That will determine flow, but that flow rate can change, if you dive deeper into things like fins per inch, number of coils, coil length, etc (though, this is unlikely to happen since our options of fitment are limited).

 

[gr8scott]

"Installed a high flow water pump."

Sometimes I believe I've heard others say that high flow can actually contribute to the problem. The thinking is that coolant flows through the radiator so fast there isn't adequate time for it to be cooled. But I'm no expert!

Good read all about cooling.

BillaVista.com-Cooling Bible Tech Article by BillaVista

 

[ared77]

^Good to know^

 

[HoldMyPocket]

I know you have this mostly fixed but one thing I didn't see mention of is that when you're running a carburetor, mechanical fan, and AC is that at least stock systems are supposed to have a little throttle kicker that receives a signal when the AC turns on, and all this does is bump the throttle a bit to make up for the load on the engine. If you don't have that, you'll be running lower RPMs which means the engine fan will be spinning slower. If you have an electric fan you can use that signal to speed up the RPM of the fan.

 

[cbunas]

I just disconnected/broke my temp guage on mine. Problem solved. Ignorance is bliss.

 

[Johnnyb]

X100 on the explorer setup: https://classicbroncos.com/forums/threads/explorer-serpentine-setup.325272/#post-3563700

 

[73azbronco]

put a Motorcraft 192 thermostat in it (RT-1139) bet it fixes your problem

This^^^^^

 

[73azbronco]

Did it run hot before you installed the ac, ?

This^^^^

did it overheat before?