My car is idle around 800, I go to the adjustment screw and it won’t change. I could get it higher but 800 is the low point. Is something stuck. I changed the intake manifold recently, yesterday I noticed one of my spark plug wires was loose and now its at a high idle. I also went and loosened and tightened y valves because I think one came loose. I cut the gasket around the base of manifold and carburetor so I know nothing is hitting. What can you guys tell me. Thank you in advance
Check the fast idle adjustments. They are on the other side of the carb.
I agree that checking the fast idle/choke adjustment is a good place to start.
If that’s not it, here are a few other things to look for:
Vacuum leak(s).
Overly advanced ignition timing.
Have you adjusted that idle fuel/air adjustment screws using a vacuum gauge? Getting them right is important for a proper idle.
You mention changing the intake manifold. Did you tighten the bolts down using a torque wrench to the proper tension? Even if you did, they need to be re-torqued after the engine has gone through a few hot/cold cycles in order to prevent vacuum leaks between the intake and cylinder heads.
Are you using stock throttle linkage? Is it the kind that bolts to the intake? Sometimes “universal” linkages, or using the provided mounting point on aftermarket manifolds will not allow the full range of throttle movement without some tweaking.
Some Ford carbs have a solenoid to bump up the idle speed in certain conditions. If yours has one, be sure to check that its functional and is properly adjusted.
A PCV valve that is stuck in the open position can act like a vacuum leak and contribute to a high idle.
Various carb problems, such as worn throttle shafts or internal leaks can also cause idle speed to increase.
Good luck. Let us know when you find it.
Idle 800, in park or drive ?
In park, it seems like the distributor had been moved. I looked at a pic from a week back and it moved. I didn’t move it, I put it to where it sounds best but timing needs to be done now. I thought fast idle screw was for cold starts, how does this effect the car at operating temp. I didn’t really want to touch that nut without knowing why since I have never moved that one before.
So after lowering timing to where I think it should be around I was able to adjust some things and sounds pretty decent right now. New question, what could be causing my throttle to get stuck. In park I rev motor and nothing gets stuck. I trimmed the inside of carburetor gasket so I know it’s not hitting that, if I’m driving and I floor it andrelease it gets stuck about half way, only when driving though. I checked the peddle, bar that goes to carburetor, fast idle valve was hitting gasket on outside of Carb so I trimmed it a little their also. Took it for a drive and it got stuck again, have to push it fast about twice for throttle to back down again, has to be something with Carb but what.
What carburetor?
What intake?
Oh sorry, it’s a holley 4150 I believe, the manifold is a weiand 8011. I do it by hand and it’s fine, get in the car give it gas everything’s OK. Drive it down the street, floor it and it doesn’t go all the way back down. Maybe my secondary are staying open, I will check that in the morning although I somewhat did by doing it by hand though, hmmm
800 in Park isn`t that hight, idle should be set to around 550 in Drive with lights on, so it goes up some when in park and neutral
Sounds like the rear throttle plates are hanging open, which only happen under full acceleration.
^That or the mounting nuts are too tight or tightened unevenly.
800 is not to bad but not being able to get it lower was the problem. Distributor had moved and timing was to advanced. That is fixed, still getting stuck though, maybe my secondaries if that is right about the full acceleration, meaning with car on and not just yanking on acceleration while it’s off lol. Strange for it wasn’t doing this a week ago. I took Carb off and must have bumped something but what
I did tighten them pretty good, I will just make them firm rather than muscle it in then. I did do it cross crossed as they recommended