Higher running temps after 2.79 to 3.80 swap

So, TL, what kinda beer should I bring?

 

As long as you're buyin', you decide...

 

I believe the general formula is your 1/8th mile time X 1.5832= 1/4

 

If the only thing that was changed was the rear end gears, then i would suspect them as not being assembled correctly, which is the cause of your engine to run at a higher temp!

 

has anyone thought that since the engine is at higher rpms.....then the engine is working harder and therfore it is producing more heat?

just my .02

 

I would go with a trans cooler, mounted in front of the radiator (right side). That's where I mounted mine. I have 3.55 gears & I've never gone over 190 degrees freeway driving. Would be a good & cheap investment. It's true the engine & trans are reving higher with lower gears. I don't have a trans temp gauge, but I do have a coolant temp guage. So far so good.....Just my 02.

 

The rear line is the return line

 

I wondered how long it would take for the this answer to pop up. You are correct on the increased rpm's, try running your stock engine's in second gear around town and see what I mean. Also if the the radiator has not been cleaned and rodded, may have a issue there too. Definately run a "big trans cooler' in front as stated before. Are you running a higher stall converter? One other thing could be a lean condition in the carb, running more R's may require a bit more fuel than before. Just some thoughts on it.

 

i cant run a tranny cooler....i have an electric fan on the front of my radiator....i guess i could sandwich the tranny cooler ( between the fan and radiator)??? good idea?? or not??

 

You could always use a remote trans cooler with it's own fan

http://www.flex-a-lite.com/auto/html/remote-mount.html

 

I added a trans cooler today, one that said it was supposed to be used for full-size trucks with moderate towing capacity. I figured I would overkill it a bit, just be safe. It was less than $40, and only $5 more than the one for "passenger cars". My temps fell from 230 to 180. When I stopped (engine off) and bought a new speedo gear to get my MPH closer to real-life speeds, it heated up to 190, and stayed there for the next 20 miles highway driving. At one point, I stopped at a convenience store for a 6-pack, and it hit 200, and stayed there at 30 mph city stop-and-go driving until I got home. Still a bit high, but it ran nice and cool on the highway.

I swapped out the 160 degree thermostat for 140. I know it will not keep the engine running cooler, but it will open up sooner. Most important, I took off the 13 lb radiator cap and put on a 16, since the 13 would run coolant into my overflow reservoir at 220 degrees, which I thought was too cool to be spewing.

Is the 16 lb cap safe for this car? What differences will it make to the running temp, if any?

Also, I swapped out the 18 tooth speedo gear for the largest the Ford dealer had, 21 teeth. I calculated that I would need 23 to be on speed. I am still 10 mph off at highway speeds. Does anyone know if there is a 23 tooth gear out there somewhere?

 

No, there's no 23 tooth gear. Steeda sells one with 22 teeth, but they are really thin teeth and are said to wear out pretty quickly. Because of my output shaft in my tranny, I needed 23 teeth just with the 3.0 gears, now with the 3.40's I've given up hope until I get my other tranny rebuilt or break down and buy that fancy new programmable electronic speedometer now.

I had alot of problems at one times with radiator caps not holding pressure, I went through 2 or 3 before I finally got one that would hold pressure even at 220 like you said. This last cap has never lost a drop even with the old motor the few times it got over 230 degrees in bad traffic on hot days.

A 140 stat is awfully low, would be open so much the water isn't going to stay in the radiator to cool very long. With an older engine, running a little warmer should not be a surprise, I had that problem with my old motor. With the new motor, same radiator and tranny cooler, with my 180 tstat it rarely gets over 190. Most of the time it sits at 180 once it warms up. The aluminum heads may help SOME I suppose. The old motor just like to run warm, may have had something to do with 6 lbs (or less) of oil pressure at idle when it was warm. :16suspect

 

I had my radiator cleaned and rodded, at least that is what the guy called it. cut the top off, ran some tools down all the cores and cleaned it out, then welded the top back on. It worked great after that, since apparently all but one of the cores (I think it has 3) were clogged. Since then, I have replaced the coolant at least 3 times: head removal, two intake swaps, and a cam change. Yesterday I dropped half the fluid, ran it through a doubled up T-shirt, just to filter out the big stuff, and put it back in after swapping out the thermostat.

So, is general consensus that I should put the 160 back in? I figured that once they open up, all thermostats are the same. Mine will just open up sooner. I recognized that (before having the radiator worked on) I ran my system with no thermostat, and the thing actually ran hotter. I figured it was because, as Mav-Matt says, the water went through the radiator so fast that it never made long enough contact with the tubes and vanes to let the heat dissipate. But will a 140 be any different in flow than a 160?

And, again, will the 16 lb radiator cap be any danger to my system, by building up too much pressure?

 

One more thing, I live in Houston, with very high humidity and hot temps for 6 months out of the year. It is already 85-90 daily, with fog and 100% humidity for the first couple hours of the day. Summer, real summer, will be in the high 90s with very high humidity. Please take these into consideration when suggesting cap and thermostat.

 

Just keep in mind that the higher pressure cap may cause another component of the cooling system to fail before pressure is released. No to bad if it is a hose under the hood that blows but a heater hose or heater core failure inside the car would really suck ...