After I installed the 670 Truck Avenger on my 69 351, I had to wait a few days to drive it untill I got my hood scoop. Anyway I had it in the drive way idling good it ran for about an half an hour as I watched for leaks ect. Well I drove it for the first time today and she ran good till i was leaving my parents place and all the sudden it revved up to about 2500-3000 rpm and wouldnt stop or come out of it. I was close to a store that I needed to go to anyway and I thought id let her cool down for a half hour or so and see what happens. She started great but immediately went up to the same rpm. I dissconnected the auto choke wire. I even backed off the curb idle screw. Neither did anything. Any ideas?
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Cody
69 Bronco, 351W, Edelbrock performer, Holley 670 T/A 35'S 5.5'' Wildhorses lift, Locker rear, F-100 power steering and a slight rear main leak
87 Bronco XLT, 302, rust, rear locker, tape player + IPOD, and the most comfortable (stock) seats ever.
Well, first, I'd set it in the drive way, with the hood open, fire it up and watch to see what happens in the carb area. If nothing happens at just an idle, then rev it lightly a few times, gradually increasing rev until you duplicate the issue. Is the throttle linkage sticking anywhere? To make it rev that high, I can't imagine a jetting problem or anything but a linkage issue. Maybe put a stiffer spring on it too.
Wondering also if there's a vacuum leak somewhere's all of a sudden.
OR ... floats sticking? Doesn't sound logical, but I keep having after thoughts right after posting. when it's revving, tap on the float housings and see if anything changes. I take it, it was running fine before the carb change. Hmmmm.... now I'm gonna go to bed and wonder. I'll wake up at 3 and come racing down here, then forget what the heck I was gonna tell ya!!!
I'll check back tomorrow to see what you found.
Last edited by Fordlover55 : 06-06-2007 at 11:31 PM.
Disconnect the throttle linkage at the carb and see if the idle comes back down.
Weak engine mounts can cause the throttle to hang up a little bit too.
It is not a common problem, but I have seen a couple of times that the throttle plates hung up on the intake manifold ports.
Check the motor mounts. If they are worn or weak your engine will move around in there and change the geometry of your throttle linkage. This happens when you drive and hit a bump and then your engine revs high or dies.
Make sure your carb springs are stiff enough and bring your throttle assembly to rest on the curb idle screw. You can alway check when you engine is going crazy like it is by placing your toes under the accel pedal and pulling it toward you. If that makes the engine calm down, check those springs.
Check the choke side. Do you have manual or electric? Lots of times problems like yours are caused by improperly set up chokes. I only use manual chokes, I don't trust the electric ones, and therefore I won't be much help setting one up.
Next step is to look for a vaccum leak. Sometime a line comes off something and caused fun things to happen!
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