How much can timing really change temp of motor? ANY EXPERTS OUT THERE?

[71 RT]

I hate to ask dumb questions, but I guess that is one benifit of being a member of this site. Nobody makes you feel too stupid!
I need one of you experts to help answer how much changing the timing of the car can affect the temperature of the car.  If the timing has been advanced  or retarded a bit,  how much will that change the temperature of the way the car runs.
The reason I ask is becuase my car runs a bit warm.  I am trying to figure out why.  I have done the normal things, replace the thermostat, temperature sending unit, water pump, rod the radiator, changed the hoses.  My car will run all day at 40 MPG and never heat up, start driving 55-60 and it will slowly heat up to the very top of the "normal" range, and then go up a little more , not peg out, but pretty hot.  I thought I had a good grip on this whole thing, till the other day when I drove it on a pretty cool day, and it never got hot at all, just barely into the normal range. I dorve it over 70 for an extended tieme, and it stayed very cool.   I know that it was a cooler day, but this difference was insane.  The only thing I can think that I did was tweek the timing.  Surely it would not make that much differenc woul it?  Any experts out ther, I would really appreciat your advice.  Thanks for your time.  I have thought it might be the fan, maybe the clutch not working properly, how can you check that.  Could it be just the timing???

[67_Dodge_Charger]

This sounds like not enough air flow through the radiator.  Do you have AC on the car?  Check the fins on the AC condensor and radiator.  Lack of air flow will reduce the cooling capabilities.  When was the engine rebuilt?  Was the fluid flushed?  Last thing would be an air pocket in the system.

good luck
Robert

[Challenger340]

No such thing as a "dumb question"
I don't know if this is related to your specific heating problem, but ignition timing's affect on engine temperature, is related to "peak" combustion temp's, and exposure, or "amount" of cylinder wall exposed to the same "peak" combustion temps.

For explanation, remember the pistons acceleration away from TDC to  peak speed in the middle of the cylinder, and it's de-celeration again going to BDC. "Rod ratio" affects this.
Due to engineering factors I can't get into here, be aware, the Piston travels FURTHER in the cylinder during the first 90 deg from TDC, than it does in the second 90 deg. to BDC.  'Nuff said, just believe me, and remember both of the above, before you read on.

Think of it this way;
Correct Ignition timing, places the full flamefront, and "peak" combustion temp's within a relatively small, but expanding area, as the piston moves down from TDC, at the top of the cylinder. Only a relatively small amount of the cylinder wall is exposed, and acting as a "heat sink', absorbing those "peak" temperatures.

Late Ignition timing, exposes more of the cylinder wall, "heat sink", to those "peak" combustion temp's, absorbing more for your cooling system to dispose of. (overheat).

Advanced Ignition timing;
can also cause overheat, because of the dwell time of the Piston @ TDC.  In this instance, it's NOT the amount of "heat sink" exposure(cylinder wall), but rather the "time" exposure on the smaller area at "peak" temp's.
This one can also also manifest itself by cracks in the chamber area, due to the CONCENTRATION of those "peak" temps, on the smaller area for the longer duration of Piston dwell @ TDC.

Hope this helps your understanding of Ignition timing, and "heat sink"

[is_it_EVER_done?]

It sounds like you may not have your vacuum advance hooked up, or it's plumbed improperly.

From my experience, retarded ignition timing can increase engine temperature by about 20 to 30 degrees.

[Rolling_Thunder]

I've had fluctuations of about 15-20*F while adjusting the timing

[firefighter3931]

Late (retarded) ignition timing will cause overheating issues. The fuel gets burned in the manifolds (or headers) instead of in the combustion chamber, where it's supposed to be. This can create an enormous amount of heat. 


Ron

[Chryco Psycho]

where is the vacuum advance hooked to ??
if it is hooked to manifold vacuum it will not run cool as the timing is retarded with RPM not advanced to allow more time to burn
I have made this change & seen cars the could not run as cool as 220 * at 70 mph instantly run at 180* @ 70 mph

[71 RT]

All good information.  I will check where I have the cacuum advance connected to, I have replaced the carb with a new Edelbrock.  I might have hooke dit up wrong.  Where is the  best place to have the vacuum advance connected?  Leep in mind this  not a full blown race car, no extra high performance neede dhere, I just want it to run within the NORMAL range.  Just to answer a few more questions, no air conditioning on this car, and yes, the car was flushed out, I do not think I have an air pocket in it.  Thanks for all of your help!

[Chryco Psycho]

the port that has no vacuum at idle & increases with RPM is the correct port to connect the dist vacuum to , or just leave it disconnected & run only the mechanical advance with the timing adjusted to 14-16* initial & 36-38 * total timing above 2800 rpm

[deputycrawford]

I would agree with Chryco on that one. Find the port that has no vacuum at idle and use it. If you can't seem to figure it out then leave the vacuum advance unplugged completely and plug the port on the carb. Rev the car to around 3000 rpms and time the car to around 36-38 degrees. See where the timing is at idle. If its around 14 degrees or so then take the car for a spin. Go from there.