We purchased standard 0.040-inch-over rings, but I will be double-checking the endgaps. What’s a good endgap to look for with the first, second, and oil rings? We’re planning on keeping it a true dual exhaust; what size piping would be good so not to lose bottom-end torque? Since getting the block and pistons back, I tried checking the piston-to-wall clearance. With most pistons not being perfectly round, I was getting a different feeler gauge reading depending on where I was checking. What’s a good clearance, and where do you check it: on the skirt or wristpin side; top of the piston by the lands, below the lands, or bottom of the piston?
Finally, based on our rebuild, what intake and carb would you recommend to take this 283 to its full potential? The only caveat is an electric choke, and we’re not opposed to Summit brand parts. Thank you for your contribution to Chevy High Performance.
The 283 is a great place to start your engine-building career. They are quite simple and there is plenty of information out there to support your build. You can either reference How to Rebuild Your Small-Block or get information from all over the Internet and you will be in good shape. Let’s take your questions in the order you served them up.
It’s always a good idea to check the piston ring endgap on assembly. Usually the only time you need to grind the ring endgap for the proper fit is when you buy oversized rings. A 0.040-inch overbore isn’t that common for file-fit piston rings. If you were to have file-fit rings for your engine, they would be 0.045-inch oversize. For a standard street rebuild, we would use the standard rule of thumb of 0.004-inch endgap per inch of bore. With your 3.790-inch overbore, that puts your top ring right at 0.015-inch endgap. For the second ring you’ll want slightly more clearance than the top. We’d recommend going with 0.018 inch for the second. This is to prevent the top ring from being lifted off the top ring land if the top ring leaks some compression gases and pressurizes the area between the top and second ring. Finally, the oil ring segments have a very wide tolerance. The chrome segments can range from 0.015 to 0.050 inch. Yes, it’s better to be on the smaller side, but it’s not imperative.
With your build, your Mouse is going to produce around 240-250 hp. This engine will work very well with a 2-inch dual exhaust. If you wish, you can go as large as a 21/4-inch tube. It would be nice if you could add a balance pipe between the two banks of the exhaust system. The Impalas are built on what is called an X-frame, which prevents you from getting from side to side under the vehicle. You’re spot-on that the bigger you get the more slow speed torque you’re going to give away. The last time we checked, the ’62 Imps aren’t very light!