This is a high-end competition...
This is a high-end competition rod bearing. It is narrower from the factory in order to work with cranks that have more fillet area. Notice how it is pulled back from the edge (the left side) of the rod.
Most aftermarket connecting rods and pistons are designed to use a Chevy-sized 0.927-inch wristpin. Clearance between the wristpin o.d. and both the piston and rod i.d. should be between 0.001- and 0.0015-inch. Measure to make sure this is right or else send your components to a machinist for honing.
Also, even if the bores in the piston's pin towers measure out right, never assume they are straight. The test for this is relatively straightforward. Insert the wristpin in the bore in one pin tower and see how easily it spins. Now slide the pin so that it extends into both pin towers. Sometimes, you can feel the wristpin catch as it enters the second pin tower. Also, if it's more difficult to spin when it's in both towers versus a single tower, that's a good sign the pin bores aren't correctly aligned and additional honing might be required.
3. Check Rod Bearing Width
Lots of performance crankshafts are made with a larger radius fillet at the edges of the journals. A larger fillet puts just a little more material between the journal and the arm of the crank, which helps strengthen the crank. This usually isn't a problem if you are using higher-quality rod bearings because they are normally cut narrower for just this reason. But cheaper rebuild kits often include stock bearings that are wider.
You can normally spot a stock-spec rod bearing because it is made from aluminum and has no babbitt, giving it a silver finish on the face. This wider bearing is more likely to ride up on the radius of the crank journal and damage both the crank and the bearing.
Take a moment to measure all...
Take a moment to measure all of your lifter diameters with a micrometer before installing them in your engine. A lifter that is only 0.0005-inch too large can cause major damage.
To check for this, install two rods-with bearings-on a rod journal and check the side clearance using a feeler gauge. You should have between 0.008 and 0.015 clearance, but when checking your side clearance check to see what's actually making contact with the side of the crank. Ideally, the cheek of the rod should hit the crank first. You won't be able to see if the bearing is riding up on the crank fillet, but you will know it if you push the rod up against the side of the crank journal and it stops before the cheek of the rod contacts anything.
If you realize you have an issue with the rod bearings contacting the crank fillet, you have two options. The first is to purchase a narrower set of rod bearings. Look for a set of high-grade performance bearings. Or, if you want to keep the set of bearings you have, you can use a bearing scraper to cut a chamfer into the outside edges.
4. Check for Valve Control
If you are performing an engine rebuild and your engine is equipped with roller-tipped rocker arms, there is an easy check to make sure your valvetrain is staying under control. Unlike flat tappet lifters which are designed to spin, valves should not. If the valves are spinning, that's a sign that they are bouncing off the seat instead of closing securely on the valve seat. Valve bounce will not only damage both the valve and the seat, but it also kills power by bleeding off compression.
When rebuilding your motor, check the valve stem tips for signs of valve bounce. If the valve is staying under control, it won't spin so the rocker tip will leave a mark in a straight line across the top. If the valve is bouncing on the seat, the spinning motion that it creates will cause the rocker tip to leave a star pattern on the tip of the stem.
Ensuring you have the correct...
Ensuring you have the correct combustion chamber volume is a critical step in any race engine build. You can have your engine machinist do this for you, but the ability to do it yourself will definitely come in handy as you continue to work on engines.
If you notice a star pattern on the end of the valve stem, you will know you've got valvetrain issues. At minimum, check the valve and seats in the cylinder heads for damage. You probably will also need to go with stiffer springs, reduce your rocker ratio, switch to a milder cam or do something else to protect your valves the next time around.
5. Avoid Sticky Lifters
It's a fact of life that more and more engine components are being produced offshore. It would be nice to buy all American, but sometimes budgets just don't allow it. You can save some money by using foreign-made engine components, but you also have to be aware that the quality often isn't to the same standard.
Lifters are one component you might think you can take out of the box, wash off and throw into the engine, but they too require a more thorough check than that-especially if you are trying to save some money with a cheaper brand. A Chevy small-block lifter is 0.842-inch in diameter and requires between 0.0018 and 0.0022 clearance inside the bore. If you happen to get one "rogue" lifter that's too large it can stick in the bore, and that's never a good thing.
A lifter is most likely to stick if the engine is brought up to temp before hitting the track, but it can happen no matter how many precautions you take if there isn't enough clearance between the lifter and the lifter bore in the block. If the lifter sticks in the bottom of the bore, it will tear up the corresponding camshaft lobe and send shards of metal through the engine. If it sticks in the top of the bore, it will force the valve open and the next time the piston approaches the top of the bore the valve and piston will be introduced in a manner that was never intended. If you are lucky, it will just bend the valve before you shut down the engine. But if the head of the valve breaks off you can have some serious damage before the driver is able to hit the kill switch.