This should be an easy one. Everybody is welcome to pipe in. The thread on optimal water temp was extremely informative for me, and I'm sure for others as well. We have a fantastic resource for knowledge here in our forum members, and some specific discussion on various topics should yield valuable information we can all use. Let's keep it up. (No Viagra jokes please)

What effect does timing have on water temp, and why? For example, if timing is retarded from optimal, does the water temp rise or fall?

-Scouder

 

If you retard timing from optimal, you lose power and temperature. Combustion occurs later, and has less time to heat up cylinder walls and other components. In short, more heat goes out the exhaust.

If you advance timing from optimal, you lose power and increase temperature. Since the cylinder will reach peak pressure before the piston is at TDC, there is more time for heat to affect cylinder walls and other components, letting less go out the exhaust.

That make any sense?

 

So in a nutshell, advanced timing will heat the cylinder/water, and retarded timing will heat the exhaust?

-Scouder

 

That's the way I understand it.

 

Ahhh, a diplomatic answer! How appropriate for tonite! I too, have understood that to be the case.

OK. Let me play devil's advocate. I had someone claim just the opposite a couple of weeks ago. They said that in a retarded condition the combustion process continues to occur as the piston travels farther down the bore on the power stroke, exposing more of the cylinder to the process and raising water temps.

Honestly, I don't see how this could be. It seems like a case of "start late, finish late", and that it would cause the combustion process to be incomplete at the time of EVO and heat the exhaust, like you indicated.

An interesting side effect of retarded timing seems to be better emissions at idle, especially if you have a long duration cam. Probably due to the heated exhaust. What say you?

-Scouder

 

I'm confused:

At what time did the retard combust? Cause, I saw nothing about on TV. Wait, I don't watch TV.

I did however vote...ain't that scary :-)

Emissions and power efficiency should run parallel. I mean, one would expect the most power when you burn the most fuel, no?

 

My experience has been that retarded timing causes the temp to increase.

(It would be easy to verify if'n I still had my Model A Ford. The lever on the left side of the steering column was the spark advance. If you forgot to advance the timing after starting it , it eventually would overheat.)

If you got an engine handy, try retarding the spark and take it for a ride. Let us know your findings . . .

 

when the timing was retarded too much,,,,,, just my experience while fooling around with the timing..... and once, when I was 16, I melted all the exhaust hangers on my Mustang playing with the timing... retard going to far... I mean retarded the timing too far

 

"At what time did the retard combust?"

Cute, Texas style. -Scouder

 

Obviously I should have focused on the effects of "advanced" timing, instead of "retarded".

Due to the "perv"asive nature of easily misinterpreted "oral" communication, as we perpetuate our automotive engine "intercourse" in our attempt to stay "abreast" of technology, I'll try to remember not to start a thread that includes the words "bung" or "o-ring" either.

-Scouder

 

Heard a story years back of a guy that used to "time" his race car by temperature

Needless to say he burnt NUMEROUS pistons and had to tear it down a few passes later.

I don't think you could actually adjust the timing and see a real difference in temp just driving around. With a thermostat it would regulate it enough that you could not see the change. Maybe with an poor cooling system it could be noticable. I think it would be a real fine line. Add to the fact that our timing is variable. If you locked it down you could keep at least ONE thing in the equation constant.

If you advanced the timing too far, it would detonate and run poorly. You could not get any heat from it. You could not produce any power, even though you would have your foot pouring the fuel to it. Retarding the timing would remove power, thus basically leaning the motor out. Lean= HEAT in a gas motor.

Diesel on the other hand, lean= cool, and fuel= heat. Two different animals.

 

-sigh- Scouder... Get your mind out of the gutter!

Probably the reason it seemed to run hot with retarded timing, was the affect on exhaust temperature I already said. Less heat dissipates into the cylinder walls due to less time exposed to peak combustion pressures and temperatures.

OBTW, the theory about more cylinder wall exposed is wrong. It's all going to be exposed anyway. The EVO event determines when it gets to escape, and the stroke of the enigne determines how much of the cylinder wall gets to be exposed.

We need to be focusing on how much time the combustion process has before the EVO event.

Also, something else with advanced timing. Not only does it increase temperature due to more time for the heat of combustion to affect the cylinder walls and other components, it also has an effect on power. Since peak pressure occurs before TDC, you lose engine power. This has the affect of causing the driver to push the gas more, causing even more fuel / air to go in and making the heating worse. Also, this can cause pinging since the extra heat will cause hotspots in the combustion chamber. This will make the overheating even worse.

So I'd say over-advanced timing is worse for an engine than over-retarded timing. Any other thoughts on this?

 

I have often used water temp gage readings to help set my timing. You need a good gage not a factory one. Usally the timing setting with the lowest temp is close to correct. Over advance or over retard will raise the temp. I check this at idle conditions inital timing. Then I use the info to set inital advance baised on engine use, temp at idle, distributor curve modifications all to figure total advance and speed of the advance curve.