Overheating On Test Stand

[archangel]

I would like to leverage the collective knowledge and experience that this forum affords. I apologize for my long initial post.

My engine overheats while running on my test stand after 15 minutes from stone cold. Once warm is it more like after 7 minutes. When I say overheats, I mean it pushes past a water temp of 200 degrees…I have gone to 210-215 at times but did want to see how far it might go.
I am ready to install it into my car but am hesitant thinking it may have some sort of major issue.

Data points:
• 1970 383 HP had been rebuilt at some point in its past life, .040 over, before I purchased it.
• I had it rebuilt, now .060 over, by a reputable local machine shop who knows Mopar engines. Stock factory equivalent Comp cam.
• Decided to run it on a test stand since there are quite a few rebuilt factory components such as water pump, fuel pump, oil pump. Also, obviously much easier to fix oil leaks on a test stand.
• Break-in went fine and it did not seem to overheat so easily during break-in oddly enough. I could run it maybe 30 minutes before it headed into the danger zone temp wise.
• I set timing (vacuum advance not hooked up…plugged on carb) by ear yesterday when I ran it but I also have used a light in the past. After setting the timing I hooked the advance back up. I forgot to capture the current timing setting when I ran it yesterday. I will next time.
• I have swapped the water pump with a new aftermarket one…no joy...went back to my factory one.
• I switched out the temperature sender/gauge to an aftermarket set. During break-in last year I had a factory sender and dash gauge. No joy.
• Using an infrared temperature gun, I am able to confirm that the temperate gauge is not lying.
• I have played the thermostat game as well. Aftermarket stat, no stat, back to NOS stat (190 degree).
• Test stand radiator is 2 row 17.5” (factory is 22” 3 row). (yes, this might be the root cause unto itself)
• Outside temperatures have run between mid-60s though high 70s during my test runs over the last few years.

It runs and idles fine. My gut feel is that it will not overheat once all of the proper cooling components are installed those being the factory radiator (Glen Ray rebuild), factory fan and factory fan shroud. In other words there is not actually a problem to fix.

Thoughts? Install and enjoy or investigate further while on the test stand?

 

[70chall440]

Either install a fan or put an independent fan in front of it. There doesn't appear to be any air being pulled through the radiator so it is going to get hot.

Also, are you running any coolant (not just water)?

 

[1 Wild R/T]

It probably needs more timing.... Put a light on it & set total timing at 36+ degrees.. A short curve and 18 base would be nice but it sounds like the distributor is stock so set total & see if that helps with the temp...

 

[archangel]

I have a box fan directly in front of the radiator (on high) blowing towards the engine. I am running 25% percent coolant at this point. It had been 50% when I started testing last year but I have drained/refilled several times over the months for several reasons. I do not have enough space to mount the factory fan although with some effort I could relocate the rad to in front of the stand making room for it. I know I can use an electric fan as well but I am sort of done spending money on the stand setup...I still might try that though.

I will try total timing at 36+ degrees. At what rpm?

 

[68-500]

Better try a real fan on there. I doubt a box fan moves enough air. Need to get a timing light on it. And also run manifold vacuum advance more timing at idle should help cool it.

 

[toolmanmike]

First off, 215° isn't overheating. A 15# cap/pressure system doesn't boil until about 255°+ when using plain water at sea level. If you aren't running an engine driven fan at least install large dual fans with a shroud. A box fan on high only puts out around 2000 cfm. Engine driven flex fans can put out 4000+ cfm at higher engine speeds.

 

[65CopCar]

I agree that radiator is a bit small. Did you verify your timing marks?

 

[1 Wild R/T]

I will try total timing at 36+ degrees. At what rpm?

Assuming you don't have a degreed damper or a timing light with an advance function....
Put a mark on the damper 2.625 to the right from the existing zero timing mark.. That represents 36 degrees...

Put the light on it, watch the timing marks, increase RPMs till the timing stops advancing.. now adjust. the distributor to align the new mark with zero on the timing tab..

 

[archangel]

Yes, on timing marks. As a side I am using stock timing cover with stock markings. Set motor at TDC, verified oil drive shaft orientation when installing, compared against distributor rotor orientation for #1 cylinder on cap.

I will work on increasing air flow and play with the timing using a light.

I appreciate everyone's input.

 

[toolmanmike]

Yes, on timing marks. As a side I am using stock timing cover with stock markings. Set motor at TDC, verified oil drive shaft orientation when installing, compared against distributor rotor orientation for #1 cylinder on cap.

I will work on increasing air flow and play with the timing using a light.

I appreciate everyone's input.

Oh boy, new engines don't like TDC timing. Give it 10-15 initial and it will be happy.

 

[archangel]

Oh, sorry, yes I had initially set it to that range. It seems to like 20-25 as I remember. On my next run I will measure and document timing numbers.

 

[#41]

Whenever I have run engines on a test stand I take a water hose and turn it on adding cool water into the top of the radiator. Then I open the petcock and make the incoming water = outgoing water (balanced water intake and outflow). The eliminates the need for a fan (which is only supposed to effectively cool the car at low rpm anyway). The engine will run at temperature as long as you have a working thermostat installed. It won't overheat or run too cool. The only thing necessary to monitor is that your water flows in/out remain equal so that you don't run low on water or overflow and take a shower.

 

[archangel]

I will consider that option as well. Very cost effective!

 

[davek]

Box fan does not cut it, More air.

 

[archangel]

All excellent feedback, much appreciated. Motivates me to do some more testing sooner than later. Striving to get my Super Bee back on the road this summer which is relatively short here in the Northwest.

 

[Lefty71]

As others have stated...how did you arrive at the point that a box fan was "enough"?

 

[archangel]

Influenced by some videos I saw albeit they were not necessarily running their motors more than a short period of time. In retrospect a poor decision on my part admittedly. I had originally envisioned all using my factory cooling parts on the test stand but once I had it in hand and mounted the engine it became apparent that room between the uprights was very limited.

 

[toolmanmike]

If you have the basics adjusted and

All excellent feedback, much appreciated. Motivates me to do some more testing sooner than later. Striving to get my Super Bee back on the road this summer which is relatively short here in the Northwest.

there are no leaks or noises, put it in the car and drive it. Most of us do it that way without issues. No reason to run it on the stand any more.

 

[YY1]

The only other thing that jumps out at me-

Your top hose is WAY high.

Might be trapping air and impeding circulation.

 

[Mick56]

Engine driven fan with a shroud