cam question
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New User
Joined: Dec 2003
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cam question
I installed a new stock cam and bearing in a 79-400,the lifters,pushrods,and crankshaft are not connected. Should I be able to turn cam by hand? How much torque is needed to turn cam . thanks!
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Joined: Sep 2001
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Yes, the cam should spin easily by hand (with the fingers) with no lifter or spring loads on it.
Yes, the cam should spin easily by hand (with the fingers) with no lifter or spring loads on it.
Posting Guru
Joined: Aug 2000
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From: PacNW
These engines are known for their bore shift on the cams. If you can't turn the cam easily then it's possible the bearings need to be reamed a small amount to get the cam to fit correctly. Whoever installed the bearings should have the tools necessary to do it.
There are other problems also with the hydrodynamic wedge and dynamic bending of the cam.
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Joined: Mar 2005
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From: Blacksburg, VA
Dave - the problem is with the definition of "easy". When I installed my cam, I could not spin it with one finger. I had to install the cam gear, and spin it by grabbing on to this. I asked around to see if this was correct or not, and got varying answers. I called up Comp Cams directly, and the tech I talked to said that they are _____ clearance bearings, and that you're not going to be able to whip the cam around in the bearings easily (sorry, can't remember the exact term he used).
Take this with a grain of salt, but that was my experience. Of course you never know how fast your cam bearings are wearing down until its too late, so I might have a problem right now and not know it....
-James
Take this with a grain of salt, but that was my experience. Of course you never know how fast your cam bearings are wearing down until its too late, so I might have a problem right now and not know it....
-James
Posting Guru
Joined: Aug 2000
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From: PacNW
Cam bearings don't suffer the same degree of wear as main & rod bearings. They're only subject to rotational stresses as opposed to the pounding the mains & rods take from converting axial motion to rotational. If it wasn't for the fact that hot tanking destroys them you could easily rebuild a motor, install a new cam without changing the cam bearings and suffer no ill effects.
Cam bearings in the 351M/400 motors are tapered and if they're reamed properly shouldn't result in a significant degradation of oil pressure.
Cam bearings in the 351M/400 motors are tapered and if they're reamed properly shouldn't result in a significant degradation of oil pressure.
