Even if the block has been solvent-washed, be sure to wash the block thoroughly, inside and out, using hot, soapy water and soft, clean brushes (small "rifle" brushes can be used to clean oil passages). Rinse the block completely and dry it using compressed air; make sure that all oil and cooling passages are thoroughly blown dry. Immediately afterwards, coat all surfaces with light oil to prevent surface rusting.
Next, you'll need to install the crankshaft main caps, tightening all main cap bolts to specification. Since the main caps will be installed and torqued during final assembly anyway, it's best to have the main caps in place and fully tightened prior to inserting the cam bearings and cam, just in case any distortion occurs within the block due to main cap bolt clamping. Basically, tightening the main caps before messing with the cam serves to pre-stress the block closer to its final state. If any distortion is present, it's better to find out now rather than later.
Before installing cam bearings, wipe all cam bores with a fast-drying solvent to create a clean and dry bore surface. Installation of cam bearings into the block must be done carefully to avoid shaving material from the outside diameter of the bearings. This galling action can easily cause a buildup of excess material between the bearing and the block's bearing bore, which will "squeeze" the bearing, resulting in oil clearance reduction at the bearing inside diameter.
Before attempting to install the cam bearings, make sure that the leading edge of each bearing bore features a slight chamfer (25-30 degrees) to ease bearing installation. Depending on the engine, the cam bearings may be "stepped" (different size for each cam bore) or they may feature the same bore size, front to rear. If the bores are stepped, arrange the cam bearings in the order in which they are to be installed. Remember, when installing cam bearings, always work your way from the rear of the block forward.
On engine blocks that do not feature an oiling groove on the bearing bores, it is vital that each cam bearing is installed in the correct clock-position, so that the bearing's oil hole accurately aligns with the cam bore oiling hole. If the cam bore features a groove, the bearing should be installed with its oiling hole placed at the 2:00 position (when viewed from the front of the block that features clockwise rotation).
By placing the bearing's oil hole at roughly the 2:00 position (anywhere between 2:00 and 3:00 is fine), oil is fed into the clearance between the cam journal and cam bearing as the cam rotates clockwise, creating an oil wedge that travels down and supports the cam much better during cam rotation. This forces a superior oil wedge under the cam, to provide oil support at the bottom (6:00) position.
As a case in point, earlier small-block Chevy blocks might feature only an oil-feed hole that aligns with the main cap oil passage, in which case the cam bearing's oil hole must align with the saddle's oil hole. By comparison, the '92-97 Chevy LT1/LT4 features a full-circle oil groove, which might lead you to think that exact clock position of the cam bearing oil hole is not important (since oil will feed into the space between the bearing and cam journal and will travel along this groove, eventually feeding into the bearing's hole anyway). However, even if a full-circumferential groove is present, as we mentioned earlier, it is necessary to position the cam bearing's oil hole at a specific position (at approximately the 2:00 position as viewed from the block front) in order to allow cam rotation to create a slight oil "wedge" during operation. This more efficiently creates an oil film between the cam journal and its corresponding bearing. Also, if the oil holes in a full-groove-type setup are aligned exactly (oil hole in the bore saddle and oil hole in the cam bearing), oil pressure can potentially feed-back, momentarily preventing oil from traveling around the journal, which can minimize the necessary oil wedge.