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Motor under pressure


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Alright so i have a 81 720 and i put a new motor in it and clutch. There are no miles on the motor or brand new clutch. However i start the truck in neutral with out the clutch and i idles fine and then drops. Then i engage the clutch and the RPMs come shooting back up. Almost feels like it is binding u somewhere. Any help? I ggot a new through out bearing and new clutch. And it is a 5 speed NAPZ2.2. Please help

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.... However i start the truck in neutral with out the clutch and i idles fine and then drops. Then i engage the clutch and the RPMs come shooting back up. Almost feels like it is binding u somewhere. Any help? I ggot a new through out bearing and new clutch. And it is a 5 speed NAPZ2.2. Please help

 

 

Are you saying:

With the motor warm it idles in neutral with the clutch peddle up (engaged) just fine...

 

when you press the clutch peddle down (disengage) the idle rises?

 

 

How much does it rise? Sounds can be deceptive.

 

Does it drive all right otherwise???

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Ok i just realized what i said was not to descriptive. I start the truck and it seems to idle at 600rpms or so then drops to around 300. Then i push the clutch pedal to the floor and it raises the idle back up to 600 or so. I dont have a tach so its guessing lol.

 

How much does it rise? Sounds can be deceptive.

 

 

Without a tach it's hard to say anything is wrong. It cold in Tucson? The gear oil will be cold and harder to stir with the tranny gears and will act like a load on the engine when the clutch is engaged.

 

Did you refill the tranny properly when you installed the clutch?

Did you grease the release bearing before installing?

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its right around 70. And its so hard tyo explain!! so imagine starting a car. when you start it it will idle high then drop a little. Now with my truck it will start high then drop rpms almost to the point of killing it self. Then i push the clutch in and it raises the idle back up to normal. Its almost like holding the brake on your car then putting it into first and letting off and the car is going to die so you push the clutch in and it idles fine. But on my truck its in neutral and it bogs down till i push the clutch in. Sorry if im making this more complicated than it is

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Here's a long shot. Don't start but switch the ignition on off on off and listen for a clicking sound at the back of the carb. ??? Yes?

 

Next look for this vacuum operated switch. It should be on the pass side inner fender. Pull off and plug the hose and see if it idles normally now.

 

vacuumswitch1.jpg

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Would that really have to do with the truck idling normal when my foot is pressing on the clutch?

 

Well I said a long shot.

 

The 720s had a fuel shut off that was supposed to only be on when decelerating in gear. There's a vacuum, clutch and tranny switch to turn the idle cut solenoid on and off under certain conditions.

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