air compressors and impact wrenches

Old 10-01-08, 08:12 AM
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air compressors and impact wrenches

how do the spec-s of an air impact wrench relate to the air compressor?
i need to loosen a crankshaft pulley bolt that is torqued at 134 ft-lb. on a 1998 honda civic LX. i have a sears craftsman 1.5hp 4-gallon 4.7SCFM@40psi--3.3SCFM@90psi air compressor. i don't yet have an air impact wrench. what should i look for in terms of psi when i go to buy one, such that i can use that air compressor to drive the impact wrench to loosen the bolt? tia.
Old 10-01-08, 09:20 AM
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all impacts that i am aware of are rated at 90 psi, continious usage will draw that compressor down but it wil work for the way most impacts are used. i use my impacts at full psi for the compressor, no pressure regulator. if you can find one a IR is a good home impact and should hold up for all of your life just oil it good everytime you put it up if you don't use it daily.
i use snap-on but that is just because it is what i bought when i was wrenching. mine are all over 20 yrs old.

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Old 10-01-08, 09:42 AM
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Torque and cfm is what you look for on the impact specs. While the cfm is probably close on all impacts, the better ones may require a little less. The higher the torque rating, the easier it will remove stubborn bolts/nuts.

I would think your small compressor would power most any impact although heavy duty use might cause you to wait on the air compressor to catch up.

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