Idle problem

[7T9BIRD]

My 79 302 66K miles, seems to want to idle high...upon cold start up, which is normal, but also when warm. I need to give it a good shot of gas a few times to bring it back to low idle. Once I put in drive and go down the driveway, if I put in neutral, it goes back into a high idle. (not as high as before, but still not normal idle). I turned down the idle adjustment and that seemed to help a bit, also seems to behave normally after a long drive, but the problem still persists.

I also noticed this past fall on my last drive for the season, I used the defrost (something I never do) and before I knew it the engine temp gauge was at it's max...turned off the heater and it went back to normal...this car is only driven about 1000 miles a year so there's bound to be little issues....any ideas?

Thanks

[Tim Cole]

Re the over heating problem; I'd suggest that your motor is running hot when the heat is turned on (such as the defroster) because the heater core is plugged up; the coolant can't flow through it like it is supposed to. Remove both heater hoses at the firewall; careful when removing it--that you don't crack the 2 brass nozzles on the heater core. Remove the screws that hold the heater core cover on; remove the cover--it will have some adhesive holding it down. Once the cover is off, lift out the heater core and run some water through it: does the water flow smoothly and quickly? If not, give it a good flush. Re-install when finished.

Your radiator might also be plugged; a radiator shop can "rod it out", cleaning out the water passages in it. Once cleaned, the coolant flows smoothly through it.

Re your fast idle: your 302-2v carb has 2 idle screws; the first screw is on the driver side of the motor and controls your normal idle RPM. Should run around 750 RPM in neutral, but lower in drive with the brake depressed.

The 2nd idle screw is the "fast idle screw." It is much smaller than the the first one and hard to see--located on the passenger side of the carb; the screw head faces the rear and is hidden from view; with a good light, carefully examine the rear portion of the visible choke linkage. You'll see a very small screw placed horizontally; it controls the fast idle cam when you start your motor.

To decrease the fast idle speed, turn the screw counter-clock-wise a half to 3/4 turn. Then, when the motor is cold, try starting it again. After a minute of warming up, give it some gas and see if it idles at a lower RPM. If it is still too high, turn the screw down another half-turn or son.

Car should idle at 750 RPM in neutral when its warmed up.

Hope that helps. Let us know how you do. Best wishes.

[7T9BIRD]

Ok Tim, sounds good. I'll adjust the idle speed(s) and check the heater core as soon as the weather allows. I was planning to flush the radiator this year anyway, just as a regular maintenance. I'll let you know how it goes, Thank you...much appreciated!

[Tim Cole]

Radiators--left sitting or used regularly need not only to be flushed, but also "rodded out." I use a radiator shop to do the latter task. Makes a difference in coolant flowing smoothly through the passages.

Another way to check for adequate flow is this: Remove radiator car: with a good light, look down into the rad and carefully examine the small series of openings through which the coolant flows; if you see rust or sludge accumulation or clogging, it is a pretty good indication that the rad needs rodding out.

[7T9BIRD]

Ok, will do. Thank you! I was thinking about replacing the radiator with an all aluminum one down the road....but this should keep it running well for this season.

[Tim Cole]

Ford used brass radiators back in the 70's; expensive and hard to find to day, but excellent for our cars. If you change radiators, I would buy a three-core (three row) unit; cools better than the standard two-row radiator. I use a three row radiator here in Florida due to the heat. Works excellent and keeps my 302-2v cool in the summer.

[7T9BIRD]

Is that 3 core copper/brass radiator or aluminum? I checked mine and it looks ok, no rust or corrosion buildup. On to the heater core...

[Tim Cole]

Aluminum radiators are all the rage today; but they cannot handle the extreme heat as well as the copper/brass units. Nevertheless, for your purposes, an aluminum rad should be OK.

[7T9BIRD]

I think your right. From what I've been reading, there is no advantage. The pro's and con's equal out for both. I think I'll stay original for as long as I can. Sent you a message, Thanks again.