I've got the XRam on and engine runs very strong. Idle is about 3000 rpms and I can't get it to adjust down. I adjusted the idle screws to where they're ready to fall out (they don't even touch the paddle) but the idle won't drop. Linkage isn't hung up. I have two 450cfm 9776 Holleys. I have a picture but need a supporting member to help posting. I know this is just plain dumb but help or suggestions would be much appreciated. Thanks.
I've Another 'Dumb' Question - Idle Adjustment
greg1ontheedge
21 - 28 of 28 Posts
yeah but 3k is awful high for a vacuum leak i have seen em run mid teens maybe to 2k but i dun think i have ever seen a vacuum leak that ran the engine to 3k
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More air, more rpms makes sense. Yeah, before I changed the manifold and carbs I'd idle about 850 rpms. But that's irrelavent now I suppose. I've got a number of things to check vaccuum related, and it don't cost nothing, and I will go through them one by one. If no vaccuum leaks, I'll start through the carbs as suggested. I'll get there but not without all the help I've gotten here. Thanks guys, can't tell you how much I appreciate the knowledge and suggestions.
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I'd have to suspect either a choke (fast idle? do those things have chokes?) or a linkage problem.
I'd start by taking the linkage off the carbs, and see where it idles.
Then pop the carbs off and see where the throttles are.
And go from there.
I agree that would have to be one heck of a vacuum leak, and I'd also wonder where the fuel is oming from. If you bottom all the idle mixture screws, does she quit running? (if she doesn't, then the throttles are open too far.)
I'd start by taking the linkage off the carbs, and see where it idles.
Then pop the carbs off and see where the throttles are.
And go from there.
I agree that would have to be one heck of a vacuum leak, and I'd also wonder where the fuel is oming from. If you bottom all the idle mixture screws, does she quit running? (if she doesn't, then the throttles are open too far.)
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Have you tried readjusting the butterflies like I suggested?
I have seen some carbs hanging up on the manifold. The throttle shaft came in contact with the carb mounting base on the intake. Make sure nothing is binding and (once you adjust the butterflies) you can see if the throttle blades will go back where they were when you had the carbs off the engine.
Is your gas pedal linkage binding?
No matter what, do not rely on a throttle return spring to return your throttle blades to idle. Always makes sure the carb will return on its own. THEN, put the throttle return spring on. Ask me how I know...Okay I tell you. I have a tunnel ram with 2 450 Holleys on my 5.0. Nothing like eight barrels stuck at WOT. Thank god my 61 Ranchero doesn't lock the steering wheel when I shut the ignition off.
I have seen some carbs hanging up on the manifold. The throttle shaft came in contact with the carb mounting base on the intake. Make sure nothing is binding and (once you adjust the butterflies) you can see if the throttle blades will go back where they were when you had the carbs off the engine.
Is your gas pedal linkage binding?
No matter what, do not rely on a throttle return spring to return your throttle blades to idle. Always makes sure the carb will return on its own. THEN, put the throttle return spring on. Ask me how I know...Okay I tell you. I have a tunnel ram with 2 450 Holleys on my 5.0. Nothing like eight barrels stuck at WOT. Thank god my 61 Ranchero doesn't lock the steering wheel when I shut the ignition off.
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388 Posts
OK gentlemen, I took both carbs off and doublechecked the secondary idle screws, then primary idle adjustment screws. They seemed to be fine but I made sure both just sit on the stop screws, not bottoming the butterflies. I reinstalled them, adjusting the throttle to carb linkage loose, to insure that wasn't hanging things up. Disconnected/plugged vaccuum to the dizzy and pb booster. Started the engine and it immediately goes to idle at about 3,000 rpms. So, is it possible I have a vaccuum leak manifold to block? Car idled fine before I replaced the manifold and carbs. Maybe there's something related to the manifold? I'm feeling frustrated and very stuck! I have 3 pistures I'd like to post if I can get somebody to help? They're jpg files but I can resave as whatever is needed. The pix are of the carbs and manifold, so you can see what we're working on, then one of primary side of 1 carb and one of secondary side of 1 carb. Thanks guys........
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You should be able to hear a vacuum leak that bad. Are you sure there is nothing hanging up with the carbs installed? What about the distributor? Is the advance mechanism sticking?
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Thanks, no I don't hear a vaccuum leak. As far as dizzy, it's electronic but was on the car when I bought it. I've had the cap off and on a number of times could I have knocked something off or something? The chain of events is: car ran perfectly with rpm performer manifold and a 600 edelbrock carb. Then I took a perfect running car 
and changed the manifold to a XC-8 Edelbrock crossram with 2 Holley 450s (model 9776). I have 1" aluminum spacers between the manifold and the carbs, that I drilled, tapped, and installed fittings for vaccuum to the PB booster. The manifold was beadblasted with no cracks, basically like new but some 35 years old. The carbs were brand new right out of the boxes. The engine runs very strong, throttle response is excellent, but she won't slow down. Well, it wasn't broke, maybe I shouldn't have tried to fix it. But it looks so cool now, and the 4" fiberglass hood is just plain bad.....
and changed the manifold to a XC-8 Edelbrock crossram with 2 Holley 450s (model 9776). I have 1" aluminum spacers between the manifold and the carbs, that I drilled, tapped, and installed fittings for vaccuum to the PB booster. The manifold was beadblasted with no cracks, basically like new but some 35 years old. The carbs were brand new right out of the boxes. The engine runs very strong, throttle response is excellent, but she won't slow down. Well, it wasn't broke, maybe I shouldn't have tried to fix it. But it looks so cool now, and the 4" fiberglass hood is just plain bad.....
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662 Posts
You could spray WD40 over everything that could be a leak just to eliminate that variable. See if the RPM kicks up anywhere.
Did you plug the holes for the old choke feeds on the carb? They shouldn't bring the idle up that much, but still it is something most people forget when they remove the chokes. There is a small hole on the side that is right next to the vacuum sec. can.
Did you plug the holes for the old choke feeds on the carb? They shouldn't bring the idle up that much, but still it is something most people forget when they remove the chokes. There is a small hole on the side that is right next to the vacuum sec. can.
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