please help me
Fleet Mechanic
Joined: Jul 2002
Posts: 1,297
Likes: 34
From: S/W Virginia
please help me
i have been having problems with my idling on my truck. I will idle fast sometimes and idle so slow it dies sometimes. This evening it went out and when i left the house the truck was idling just fine. When i got to a red light about 15 minutes later it was idling so slow it was about to die. when i got where i was going about 2 minutes later, it was idling fine again. its manual choke and i have the fast idle cam disconnected so i know its not it. any ideas??
Senior User
Joined: Oct 2001
Posts: 222
Likes: 0
From: Las Cruces USA
please help me
You didn't say what carb you have. If it's a Holley 4bbl (like my 4160), I can tell you what I found when mine had the same symptoms.
I couldn't adjust the idle; it kept varying all the time. I would set it at 700rpm and it would be 950 at the first stop-light and 800 at the next stop sign.
What I found was a problem with the secondaries. The secondary throttle shaft is installed into the throttle body (at the factory) using teflon sleeves which act as mini-bearings. I assume this is to eliminate or greatly reduce drag and shaft wear. The older carbs I've rebuilt in the past didn't have them.
The teflon had worn to the point that the shaft would bounce around enough to open the 'butterflies' a tiny bit, thus changing the idle.
And if I got into the secondaries when excellerating, it would often be even worse. The shaft would turn, and then bind up in the throttle body and not close completely.
I replaced the secondary throttle shaft with one out of an older model If you do this, be sure to 'pean' the screws that hold the throttle plates in the shaft). It was working just fine until I decided to rebuild the carb. Now I have other problems.
Perhaps you can pull the air cleaner when it is idling too fast and, with a long thin screwdriver, reach down the secondary side and push the plates to see if they close. If you push the wrong way, the engine will speed up.
OldFords
bad attitudes
I couldn't adjust the idle; it kept varying all the time. I would set it at 700rpm and it would be 950 at the first stop-light and 800 at the next stop sign.
What I found was a problem with the secondaries. The secondary throttle shaft is installed into the throttle body (at the factory) using teflon sleeves which act as mini-bearings. I assume this is to eliminate or greatly reduce drag and shaft wear. The older carbs I've rebuilt in the past didn't have them.
The teflon had worn to the point that the shaft would bounce around enough to open the 'butterflies' a tiny bit, thus changing the idle.
And if I got into the secondaries when excellerating, it would often be even worse. The shaft would turn, and then bind up in the throttle body and not close completely.
I replaced the secondary throttle shaft with one out of an older model If you do this, be sure to 'pean' the screws that hold the throttle plates in the shaft). It was working just fine until I decided to rebuild the carb. Now I have other problems.
Perhaps you can pull the air cleaner when it is idling too fast and, with a long thin screwdriver, reach down the secondary side and push the plates to see if they close. If you push the wrong way, the engine will speed up.
OldFords
bad attitudes
Post Fiend
Joined: Jun 2002
Posts: 13,873
Likes: 3
From: Atlanta GA
please help me
My truck was doing this. I decided to fork out the money and buy a dwell meter and set the points to spec. instead of just gapping them. It made a big difference in the idle after I set the timing.
