Wierd. low idle=overheat?

[PH4]

Just adjusted the idle on my Zenith carb because I felt it was idling too high. Backed the screw out to right above stall and then drove it around block. Did great but as pulling into driveway noticed tempeture guage at hot. Live in Charleston with high temps but the guage has never gone above barely cold. Would lowering the idle produce this effect? Seems wierd to me. Could have happened while sitting in driveway tinkering with idle but just seems wierd? Any help much appreciated. Daily driver so need to figure it out.

[daveb]

higher idle keeps the fan moving @ higher speed = more air pushing through radiator = ostensibly better cooling. it could be some other part of your cooling systme is not functioning to the best of its capability, i.e, raidator partially blocked, incorrect thermostat (american one with no skirt to cover the bypaass) water pump impeller corroded, etc etc

Just adjusted the idle on my Zenith carb because I felt it was idling too high. Backed the screw out to right above stall and then drove it around block. Did great but as pulling into driveway noticed tempeture guage at hot. Live in Charleston with high temps but the guage has never gone above barely cold. Would lowering the idle produce this effect? Seems wierd to me. Could have happened while sitting in driveway tinkering with idle but just seems wierd? Any help much appreciated. Daily driver so need to figure it out.

[Jeff Aronson]

Overheating

Most likely, the change in idle speed is not the sole reason for the overheating. Dave is quite right - too low an idle will elevate the temperature as neither the water pump nor the fan turn rapidly enough to do their work effectively. You wrote that you drove it around the block. Did it overheat then, or only when you idled for a while at the end of the test drive? If that's the case, did the temperature drop quickly when the car was moving?

I have found that in hot summer weather I need to have my radiator [replacement thin neck] on my II-A quite full in order to maintain a very low idle and not cause some hot running. Also, I have always made certain that I run a summer thermostat rather than the 190 degree winter one during the summer. That makes a difference, too.

Good luck,

Jeff

[daveb]

jeff-

do you have the fan shroud fitted? I neve rhad any problems with 2.25 cooling even down here in DC 100 degree summers.

rgrds
dave

I need to have my radiator [replacement thin neck] on my II-A quite full in order to maintain a very low idle and not cause some hot running. Also, I have always made certain that I run a summer thermostat rather than the 190 degree winter one during the summer. That makes a difference, too.

Good luck,

Jeff

[PH4]

It took awhile to cool down. I noticed it as I was pulling in the drive. Once it cooled down I checked radiator and it took a great deal of water. I believe the low coolant coupled with the reduced idle was the culprit. No problems since. Thanks for the advice.