The Dodge Challenger Message Board

Newly built 440, pretty mild. I have about 80 miles on it so far. When driving, even in mid to high 80's, it runs cool, when idling, I am worried about overheating. If it idles for 10 minutes or so, it gets hot.

I have a 26 in. radiator that I had recored. I have a flex lite belt driven fan, and a 180 thermostat.

I was considering adding a pair of electric fans to push from the front. Any suggestions? Am I jumping the gun on this one, should it run cooler once I have a few hundred miles on it?

Thanks for any advice.

New motors due tend to run hot, I remember the paint bake makes you think it's really toasting in there too. As long as there is no coolant loss the factory type system is fine IMO.

How much initial timing do you have?
What is your idle mixture set at?

Thanks guys for the responses. I am not losing any coolant, small amount on one header bolt I need to fix, couple drops after running it.

I have the initial timing at about 18 degrees, and all in is about 55.

I set the idle mixture (even on both sides) by getting the vacuum up to about 15. If it is too lean will it run hotter?

I did bring the idle down to about 800, it was around 950-1,000. Will that help it idle cooler?

Thanks again.

Not enough initial timing will make it run hotter at idle.

Without any vacuum advance you should have at least 18 degrees initial and no more than 35 degrees at 3000rpm with no advance over that rpm. Get the timing half in by 2000rpm.

With manifold vacuum used to gain more timing at idle I would expect to see more advance than that at idle.

Yes too rich or too lean can make the engine run hotter in different ways.

Adjust the mixture just very slightly to the lean side of MAX vacuum at idle. If it will idle OK at 800rpm yes that will help it run cooler too.

Rich, do you use a shroud? Is the flex-lite fan spaced too far away from the rad?

Hey Eddie,

I do have a shroud, the fit is not the best, I am planning to work on it. Sort of a mismatch to the radiator, but with some mods I can really improve it. Does it make a big difference being tight with the radiator? I imagine it would.

I have a 2 inch spacer on the fan. I would guess (can measure later) that is is within 3 inches of the radiator.

I don't mind spending the extra money to have it run cool, just want to make sure everything else is correct too, so as to mask another real problem. The engine is just about stock, so all these small things should add up.

Thanks again.

The shroud is vital for low speeds, since there is so much airflow across the core at highway speeds a shroud or even a fan isnt necessary. But at idle it's vital, it sounds as if it's too far away from the rad, it should be as close as possible without hitting of course. To be honest, I never really liked those flex fans, I prefer a clutch or T-Stat controlled fan like the factory used. Just make sure to heed Dave' advice regarding timing and carb mixture settings and you should be fine. Also the factory gauges are notoriously inaccurate. You can get a cheap IR temp gauge at harbor freight for a few bucks just to make sure it corresponds to the gauge and measure it at idle with the engine at operating temp and checking T-Stat housing, hoses, radiator for blockage ect. Real handy tool!

Thanks Eddie,

The fan is actually 1.5 inches from the radiator. I will fit the fan shroud this weekend, recheck the timing and carb settings too. Hopefully that will get me there.

I will buy a temp gauge too, I am sure the factory one is not really accurate.

Dave, I saw on another post that you removed the vacuum completely from your distributor and dialed in 26 degrees. Still working out well?

From your older timing post it sounds like 35 with no vacuum and 55 with (both at 3,000 rpm) is what the goal should be. I will check both ways and see where I am at.

Thanks again for the advice.

Working well and running cool as a cucumber.