Assembling a good engine is...
Assembling a good engine is less about high-dollar parts and more about taking the time to measure everything and accurately bolting together the parts the right way.
If the engine is still in the vehicle, look for one with as few miles as possible. Finding one with less than 100,000 miles may be difficult but not impossible. We own a 350 engine in a 1/2-ton pickup with 100,000 miles that uses very little oil and has acceptable fuel mileage that would make a perfect budget rebuilder.
Last month, we showed you how to diagnose a used engine. It's best to dig a little deeper to pull the heads and check out cylinder wear. If any cylinder exhibits a deep ridge at the top of the ring travel where maximum bore wear occurs, avoid this engine. The ridge indicates excessive cylinder bore taper that will not seal well with just new rings. The fingernail test is a good way to check for bore wear, but be sure what you are feeling isn't just mild carbon buildup. Scrub the carbon from the top of the cylinder and you may find minimal wear. Also look for excessive sludge in the lifter valley and valve covers. Excessive sludge usually indicates that the engine was not well cared for and means you need to keep looking.
 Used engines are where you...  Used engines are where you find them. We ran across this small-block at the junkyard. The rust in the No. 3 cylinder was very mild. This engine had very little detectable taper, so the rust should come out with a hone. |  Use your fingernail to check...  Use your fingernail to check for bore taper. If you notice excessive bore wear at the top of the ring travel, keep looking for a better engine. You can also measure the cylinder wall taper with a simple dial caliper that will tell you if it has been overbored. Don't discount a 0.030-over engine-it may have fewer miles. |  Be on the lookout for one-piece...  Be on the lookout for one-piece (shown here) versus two-piece rear main seal engines. Chevy changed the crank seal in '86-and-later engines, which is a major improvement. Be aware that this will require a different flywheel/flexplate due to a smaller bolt pattern. Most one-piece seal engines came with provisions for a roller cam. However, a flat-tappet cam will still work in a roller block. One minor negative to one-piece blocks is that the gasket sets are more expensive. |
 If you're really serious,...  If you're really serious, yank the pan and look for excessive wear on the rods and mains. Pulling the No. 1 main cap will tell the tale, since it's the farthest from the oil pump. You don't want an engine that looks like this unless you have a spare crank. Pass on any engine that exhibits a blue or black ring to the main or rod caps. This indicates excessive heat. | | |
The Jerk And Clean
Before you take anything apart, the best plan is to mark all the rods and caps. The factory usually marks the main caps, but if not, indicate one through five and also note the orientation of the cap to the front of the engine. This is usually marked with an arrow, but if not, you'll need to create something, since this is critically important. Disassemble the engine slowly so you can eyeball any potential problem areas. The smart move is to completely disassemble the engine and have it professionally cleaned by a local machine shop. The only issue here is that this adds cost not just for cleaning but also to install new cam bearings. In our search to minimize cost, we're going to clean the engine ourselves and leave the old cam bearings in place.
 We removed the plugs from...  We removed the plugs from both ends of the oil gallery to hit this area behind the cam bearings with a long brush. Spend some time here to get this as clean as possible. We used lots of spray carb cleaner. If possible, collect the drippings in a drain pan so they don't stain the concrete or eat your asphalt driveway. |  Mark the rod and caps on the...  Mark the rod and caps on the outboard side. If you don't have a numbers punch set, borrow one. The center punch idea will work, but it's crude, and eight punches on the last rod will be hard to read. |  Once the engine is disassembled,...  Once the engine is disassembled, it is time to hit the cylinder walls with a deglazing hone. These are sometimes called dingleball hones, since the ends of the brushes use small abrasive balls to remove the glazing on the cylinder walls. |
 Remove the oil gallery plug...  Remove the oil gallery plug from the driver side deck surface and use a rifle bore brush to clean this vertical oil passage that connects to one of the main oil galleries. We also spent some time running a tap through all the head boltholes. An old, loose tap is better, since we want to clean the threads and not remove metal. |  Sanitize the block, heads,...  Sanitize the block, heads, crank, rods, and pistons as much as possible. The cleaner the engine is, the better the chance of minimizing bearing damage during initial start-up. Laundry soap works very well to remove grease and oil. This is our final cleaning process with this engine, having already painted the block and installed the brass freeze plugs. | |