The parts and the math behind them At RPM, we think it’s pretty important for readers to understand each part and why it has been chosen, as well as the steps involved machining and assembling an engine, so don’t be scared by the word “math” in our subtitle. There is a bunch of support in our industry to get you heading in the right direction with building your own motor or choosing one of many great builders that will take care of everything for you. In either case, you most likely won’t have to toil over formulas, but if you do plan to self-build or at the very least be actively involved with your builder’s work, it is an asset to understand the whys and hows of the process. To date in our World Domination SBF build, we have completed the crankshaft balancing and cylinder boring procedures. We talked about the World Products 9.200 deck block main bores measuring to specification. Recently at Kraushaar Machine Services, we loaded a set of main bearings in the World block in order to check the main oil clearance. We torqued the caps to the required 70 ft lb with moly. After measuring each main bearing ID, compared to the corresponding crankshaft main OD, 76
april 2021 | RPM Magazine
■ Now that the cylinders are bored to the correct diameter, I have installed a piston in one corner of the block to measure where the piston sits in relation to the deck of our World block. We want all the pistons to be at the same height in each bore, this verifies the deck is correct at 9.200” and is square from end to end. the oil clearance fell into the .0025”to The oil clearance math .0027” range. If you remember from looks like this: other RPM articles, I personally like Stroke 4.0 / 2 + Rod length 6.00 to run .001” per 1” of OD journal di+ Piston Compression Height (CH) ameter. Our crankshaft is a Cleveland 1.200 = 9.200 main design, measuring 2.749”, thereTo complete our World Products fore, I would like .0027” oil clearance. All good again and we can move on! block measuring and machine work,