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You've disassembled the engine and there's a lot to measure and check to determine what needs to be done -- crankshaft journals (mains and rods), cam shaft journals, pistons, cylinder walls, heads .... it's a lot, to be sure! And just because something *looks* good, doesn't mean it *is* good ... Don't take anything for granted! Don't forget the ole ...
Since you've gone to a lot of trouble and expense to make the crankshaft round and smooth and the right size, it's logical to do the same thing to the big ends of the rods. At 2,000 RPM, that rod is changing directions 66 times a second, for untold millions of cycles. No wonder they stretch a little from top to bottom! As you remove the pistons (with their rods still attached, of course), mark them with a sharpie with the cylinder number. To remove the rods safely, don't put the piston or the rod in a vice and wang away at the pinch bolt! When loosening the pinch bolts at the wrist pin area, support the wrist pin by clamping a tapered punch into a vise and slip the pin over the punch. That keeps the rod from getting twisted by torque on the bolt. With the pistons seperated from the rods, you can have a machinist check the rods for bend or twist. Also, check the inside diameter of the big ends of the connecting rods. Remove the bearing shells, torque the nuts to their normal specification (40 ft/lbs.) and measure the diameter with an inside micrometer. It should be round, and within 1/2 thousandth +/- of 2.437 inches. If the rods are stretched or out of round, the oil clearance on the bearings won't come out right. The reason I specified an inside micrometer is that a dial caliper or a digital (even my $300.00 Starret) just isn't accurate enough to check a connecting rod. An inside mike or a dial bore gauge is my accuracy benchmark. Should you want to try fixing an out of round big end yourself, you can file or grind a small amount of metal off the parting line area of the rod and cap and recut the hole round and to the right diameter on a Sunnen hone. It's called "rod reconditioning" and it's been done for decades by good automotive machine shops. -30-
We live in the land of the free, because of the brave who left home on our behalf. |
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