Re: Dhadley, To bore all the same size or not
It'll be fine as far as balance and weight. No problem there. The problem comes in on the measurements of the others. Theres a great temptation to say "the rest look good" and just replace 1 piston. If the other cylinders measure good, thats one thing but if you dont measure them you dont know.<br /><br />Food for thought -- many times we've seen guys have the cylinders measured and they are within wear spec. Then they hone them, which takes out material, and the pistons are real loose and noisy. And the guy wonders why. The only way to know which cylinders are to be bored is to measure them with a dial bore gauge.<br /><br />Back to your weight thing -- When we started drag racing we just used a V4 looper that was on the ski boat. We spent the first season getting the balance and props dialed in. When I bought the motor it had 1 .030 piston and 3 standard pistons. It all measured up pretty well though. <br /><br />By the end of the first season we were turning it about 8000 rpm. Blueprinting and balancing was not allowed, you had to run a stock powerhead as produced. Over the off season we built a fresh powerhead all .020 over. Weighed rods til I was blue in the face to find 4 that were EXACTLY the same weight, and all piston assemblys were the same weight. Guess what? It still turned the exact same rpm. <br /><br />The point is that the first powerhead with 1 oversize piston ran that season at 8000 rpm and then was back on the ski boat. Never did have a problem with it.
