68 Dodge Charger 440 Running HOT

[Charger68RT]

Get a laser temp gun and keep going down the line.    Write down each temp as the engine runs longer.

My 68 Charger had a restrictive water pump housing on it.   There is a thread that talks about the 400 source bad batch of housing and a bunch of us had one.   The other aspect that I learned the hard way was there are two different gauge readings that you can get.   As in the numbers are in two different positions compared to the needle.   Like someone said, if you put on a secondary mechanical gauge this could help also. 
You
My Coronet, it was the same situation as your to a tee.   Years and years of it getting hot wound up being a clogged radiator.   Even though I had a re-cored radiator when I did the refresh on the car, it still was clogged and caused it to run like your car.    I bought a YearOne aluminum and it has been fine since then.

I read your post and feedback on the issue with the water pump housing blockage. Interesting. I don't understand how company's know long make something that is wrong and untested. It's about MONEY.  I'm trying real hard to keep the car all stock. When I had the radiator re-cored I told the radiator shop of my heat issue and he told me he would add additional vertical rows that would fit in the same radiator frame. More vertical rows that are smaller and would cool better. He told me he had done this many times in the past on old radiators and it has helped.  I think I need to install a mechanical gauge and start over checking my temps at various locations.  I guess you would have to break down the radiator completely to see if the core is clogged again.  Correct?  Thank you for your help and feedback.

[Charger68RT]

I had a very similar problem with my '72, recored radiator and all. The issue? Mice made a home in part of the core while it sat waiting to be installed. If radiator sat for a while worth looking for junk in the radiator.

I will flush it out once again.  I would never think to check for mice. Thank you for the feedback.

[Challenger340]

You mentioned a Compression Ratio check being "all good" ?    and an Engine run-on "dieseling' condition ?

HOW was the CR test performed ?
WHAT were the numbers ?
and even better seeing as how the engine was just rebuilt ?
WHAT Pistons were used on WHAT Cylinder Heads ?

[Charger68RT]

You mentioned a Compression Ratio check being "all good" ?    and an Engine run-on "dieseling' condition ?

HOW was the CR test performed ?
WHAT were the numbers ?
and even better seeing as how the engine was just rebuilt ?
WHAT Pistons were used on WHAT Cylinder Heads ?

When I did the compression test the engine was cool. I pulled all plugs and tested each cylinder one at a time. All tested at 160 plus or minus 5. I used a screw in type Round dial gauge. I let each cylinder cycle three times to take the reading. The dieseling is something that just recently started. I don't know the details on the new pistons and the heads are stock. I would think there is only 200 miles since the motor was built not counting the time spent idling trying to test and isolate the heat issue. The shop that did the work has been closed for over two years. The motor seems to turn over easily and there is no binding. It starts easy and there is no white or black exhaust smoke. Thanks for the feedback and help

[Challenger340]

You mentioned a Compression Ratio check being "all good" ?    and an Engine run-on "dieseling' condition ?

HOW was the CR test performed ?
WHAT were the numbers ?
and even better seeing as how the engine was just rebuilt ?
WHAT Pistons were used on WHAT Cylinder Heads ?

When I did the compression test the engine was cool. I pulled all plugs and tested each cylinder one at a time. All tested at 160 plus or minus 5. I used a screw in type Round dial gauge. I let each cylinder cycle three times to take the reading. The dieseling is something that just recently started. I don't know the details on the new pistons and the heads are stock. I would think there is only 200 miles since the motor was built not counting the time spent idling trying to test and isolate the heat issue. The shop that did the work has been closed for over two years. The motor seems to turn over easily and there is no binding. It starts easy and there is no white or black exhaust smoke. Thanks for the feedback and help

You are using straight 91 Octane premium fuel correct ?


Gauges can vary, nonetheless, 160 is high enough to continue investigating too much cylinder wall exposure to peak combustion temps from high cylinder pressure.
What I mean is this....
peak combustion temps need to be concentrated within the top 1-1 1/2" of the cylinder throughout the rpm range = good distributor timing curve.

Quick "test"
is to verify the initial timing at idle(10* ?) if it will still crank/start nicely there
verify at 3,000 rpm NOT exceeding but as close to 28-30* as possible
Verify NOT continuing to advance past 34-35* as rpm's flash higher past 3,500 rpm etc.
Then
purge the fuel tank.... ort get it down as close to "E" as possible.... and add about 5 gallons of C12 High Octane Fuel or even 101 Low Lead AV Gas and run it to see if the overheat condition is cured.

If it does cure ?
Then static CR is too high and some fancy footwork tuning fuel mixture curve work is in order to get back running cool on premium 91 Octane.

[Charger68RT]

The factory gauge may not be accurate. Check with a mechanical one before beating your head against the wall. Dieseling can be heat build up in the carb and too high an idle with the ethanol fuels

I purchased the mechanical Temperature gauge.  The new sensor connector fitting does come
With multiple adapters but it will not fit the 3/8" hole from the stock temperature sensor. Where else can I
Install the new temperature sensor?  Thank you

[Charger68RT]

What fan/ radiator setup do you have?  If you have the fan clutch setup, the clutch could of went out.  Also, not having the fan close enough to the radiator could cause you issues.  Not having a shroud, could cause you issues.  If you're running an electric fan setup, your fans could be running the wrong direction, or not working at all.

The fan, shroud, radiate, and fan clutch are all stock. I double checked and the fan has 7 blades like it is suppose to. I changed the fan clutch with a stock aftermarket just to be sure.  I will put the Dodge one back on when I get the heat issue resolved. Than you for the feedback. How close should the fan blades be to the radiator?  Less than 1 inch?

About an inch

I will check. Thank you.

[Charger68RT]

You mentioned a Compression Ratio check being "all good" ?    and an Engine run-on "dieseling' condition ?

HOW was the CR test performed ?
WHAT were the numbers ?
and even better seeing as how the engine was just rebuilt ?
WHAT Pistons were used on WHAT Cylinder Heads ?

When I did the compression test the engine was cool. I pulled all plugs and tested each cylinder one at a time. All tested at 160 plus or minus 5. I used a screw in type Round dial gauge. I let each cylinder cycle three times to take the reading. The dieseling is something that just recently started. I don't know the details on the new pistons and the heads are stock. I would think there is only 200 miles since the motor was built not counting the time spent idling trying to test and isolate the heat issue. The shop that did the work has been closed for over two years. The motor seems to turn over easily and there is no binding. It starts easy and there is no white or black exhaust smoke. Thanks for the feedback and help

You are using straight 91 Octane premium fuel correct ?


Gauges can vary, nonetheless, 160 is high enough to continue investigating too much cylinder wall exposure to peak combustion temps from high cylinder pressure.
What I mean is this....
peak combustion temps need to be concentrated within the top 1-1 1/2" of the cylinder throughout the rpm range = good distributor timing curve.

Quick "test"
is to verify the initial timing at idle(10* ?) if it will still crank/start nicely there
verify at 3,000 rpm NOT exceeding but as close to 28-30* as possible
Verify NOT continuing to advance past 34-35* as rpm's flash higher past 3,500 rpm etc.
Then
purge the fuel tank.... ort get it down as close to "E" as possible.... and add about 5 gallons of C12 High Octane Fuel or even 101 Low Lead AV Gas and run it to see if the overheat condition is cured.

If it does cure ?
Then static CR is too high and some fancy footwork tuning fuel mixture curve work is in order to get back running cool on premium 91 Octane.
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I'm running Sunoco 93 premium.  What is static CR?  I have the " Clean Air Package" installed and my mechanical timing is set at 0 TDC.   Should I continue to test for 28-30 at 3000 RPM?  Or bypass the Distributor Vacuum Control Module and start at 10 at idle?  Thank you for the feedback.

[RollinThunder]

Lean A/F and late timing. 

Drill out the IFR's 0.002" larger and change idle timing to 16 degrees (make sure total does not go past 34 deg...).   Then make sure no fuel drips from the boosters at idle, and keep opening the IFR's until the idle mixtures screws work.  Closing the screws should stall the engine, and 4 turns out should be very rich.   About right has the screws 1.5 turns out. 

if you have enough vacuum at idle, you can increase idle timing by using manifold vacuum source to the vacuum adv.  In fact, you may want to try this first.
My car cranks at 12 degrees then it pulls vacuum adv and idles at 29 (pulls in about 17 degrees vac adv from manifold source at idle).