I have a 1975 f250 with a 390 and my truck will not idle the same way eveytime. somedays its runs and idles perfect others it wont idle good at all and dies at every stop. I DONT KNOW what my problem is. I need help to get me back in the mud thanks for the help

 

Do you have a stock Carb? If you do check it all out, take it off clean it, replace the seals, check the movement of your choke, if its electronic check the connection. If your idle is different every day no matter what the weather, then check your timing, but alot of the time the weather will have an effect on it, there is a temp. sencitive spring that controls your choke and if its warm out it will already be open, and if its cold then it will be closed untill it warms up from the temp of the engine. Check that stuff and we will see what happens.

 

its an aftermarket eldebroke carb with a manuel choke. tomarrow i am going to check that carb all out. But I am not sure how to do the timing. I was told that might be the problem. any help on how to do the timing would help alot thanks.

 

find the harmonic balancer on the engine, usaly located under the water pump, it should have marks on it (TDC 0-10-20-BTDC and so on). TDC is Top Dead Center and BTDC is Befor Top Dead Center. That is the Position of the piston when it detonates. You will need a timing light or you can do it by ear. If you have the light follow the directions for the light because there are diffrent types of lights. If you donot have a light and want to do it by ear what you have to do is: Start up your truck let it run/drive it untill its at normal every day operating tempurature, adjust your idle if it is to high or to low, find your distributor hold down bolt and loosen it untill you can turn the distributor left to right, adjust it left or right (clockwise or counter clockwise), untill it sounds beter than it did befor, your idle may go up or down, its trial and error when you do it by ear, you have to adjust the distributor, tighten it down adjust the idle, shut the truck off, start it up to see if it starts alright, if it does not start dont panic! Just loosen the distributor and move it 1/6 of a turn left, and if thats not it then do it right, but you shouldnt have that problem. Just do that untill it is running good. Shut if off come back to in the next day and see if it worked if it did not work and you have checked your carb , check your Spark plugs, spark plug wires, distributor cap and Rotor. These things are cheap to replace and should be replaced every year to 2 years.

 

Do you have an "EGR" valve on the engine?