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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Buddy on January 30, 2011, 07:03:33 pm

Title: high idle help
Post by: Buddy on January 30, 2011, 07:03:33 pm

Ok I have an 85 4x4 with a 305, i bought this truck and did a total rebuild, not done yet but getting close. The motoer is a 79 and I have been told it has been rebuilt. I have had problems getting it to run right since i did all the work. I never did any thing to the motor, i had it going with a holley carb that came on the truck. a friend told me that the carb was bad causing all my starting and stalling problems so i switched to a newly re built quadrajet. truck starts up somewhat good and sound heathly when it goes i just cant get the idle to calm down. it is idle at 2 grand when it starts and i can get it to settle down to around 1100. seems high to me, when i shift the truck it feels like it is going to jump right through the garage. put it in reverse and it seems like I have to be a sprint car driver to handle the speed of reverse. I am sure all of this is from the idle. how do i get this down. I have the idle screw turned down so low it not even touch any more still idles crazy high. I know my timing is out of wack a bit because it still running for a second when i turn it off. it also seems that it is running rich, burns the eyes if i have the garage door closed. I am no mechcanic but i can trouble shoot with some guidance. dont know anything about carbs at all. I do know that I do have vacum and that my PCV valve works. I have also removed all my canister stuff as well.....any help would be great

Title: Re: high idle help
Post by: 1979C20 on January 30, 2011, 07:24:59 pm

Set your idle mixtures screws. And check your timing.

Title: Re: high idle help
Post by: Buddy on January 30, 2011, 07:29:29 pm

how do I do that? what should the screw be set at where do i start?

Title: Re: high idle help
Post by: Buddy on January 31, 2011, 01:34:44 pm

anybody?????

Title: Re: high idle help
Post by: Grim 82 on January 31, 2011, 01:53:12 pm

If the throttle isn't resting on the idle speed screw then it's probably set on the fast idle cam for the choke. If you tap the gas does it idle down? Also make sure the throttle return spring is hooked up and doing it's job. A vacuum leak somewhere can also make the idle high, but make sure that the linkage on the carb itself is working properly first.