grooved oil bearings

Discussion in 'Race 400/430/455' started by rh455, Apr 3, 2002.

  1. rh455

    rh455 Well-Known Member

    I read somewhere that TA grooved cam bearings are to be installed with the oil hole in the bearing at 3:00 o'clock and not to align with the oil holes in the journal. Is this right? :Do No:
     
  2. Dave

    Dave Speaksoftly/Carrybigstick

    Reynold:

    The backgrooved cam bearings supply oil obviously through the grooves in the backside of the bearing. The stock Buick bearings supply oil to the cam journal directly to the bearing surface. The stock holes supply oil at the 9 o'clock position, from here oil is carried in the groove in the #1 cam journal over to the drivers side lifter galley and also supplies oil to the bearing surface for cam bearing lubrication. The camshaft journals use a wedge of oil (called a hydrodynamic wedge) to insulate or cushion the space between the journal itself and the bearing surface. What happens is when oil enters at 9 o'clock it is dispersed throughout the area of the bearing, so the thickest wedge of oil is at the 10 o'clock position and gradually gets thinner and thinner as it goes around the bearing (clockwise rotation). So at the 4 o'clock position it's getting pretty thin and by 8 o'clock its thinner still. Most of the force on the bearings is at the 4 to 8 o'clock positions, where the lifters are pushing down on the camshaft. And since this is also the thinnest wedge of oil or less cushion this is where you will first realize a wiping of the bearing. So the thickest wedge of oil is from the 10 o'clock through 2 o'clock position, where it is needed less as there is no upward force on the camshaft. So if you oil the bearing from the backside and reclock the entrance hole to 3 o'clock where it's needed most you'll get the thickest wedge of oil from 4 to 8 o'clock. The new TA double backgrooved bearings have two entrance holes one at 3 o'clock and 7 o'clock. This way you'll get the most oil where its needed the most. If you're using the older style single backgrooved bearings install the single oil hole at 3 o'clock. Hope this helps explain the process.
     

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