April '19

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34 THE SHOP APRIL 2019 APRIL 2019 Engine Products p.42 PRECISION ENGINE EDITOR'S NOTE: This is the fifth and final installment in a multi-part series following the build of a 632-ci big-block drag racing engine. See Part I in the January 2018 issue of THE SHOP, Part II in the April 2018 issue, Part III in the July 2018 issue and Part IV in the October 2018 issue.. W ell, the motor was final-assembled and run on the dyno. While we didn't hit our hoped-for 1,200 hp, we did manage a nonetheless impressive 1,115-hp run. With further tuning, we know the potential is there. First, we'll review our Dart cylinder head specifications, followed by the final stages of engine assembly involving the ignition system, fuel system and vacuum pump setup, finishing with our dyno cell results. See image 1. DISTRIBUTOR I initially ordered an MSD distributor (P/N 8558, Pro Billet low-profile distributor), but quickly discovered that the large 5-inch- diameter head wouldn't clear our tunnel ram manifold's plenum box. I obtained a replacement, MSD P/N 85501, one of MSD's Pro Billet units, fea- turing a lockout (no mechanical advance). Upon checking distributor fit, I found that the nose of the bronze distributor gear con- tacted the block (touching a boss inside the block at about the 1-o'clock position as you stare down into the distributor bore). Instead of stripping back down to a bare block to grind clearance, I followed Scott Gressman's advice by applying machinist blue to the bronze gear assembly, inserting the distributor as fully as possible, and rotating the crank one full revolution. Upon removing the distributor, I noticed a contact path around the perimeter of the gear nose (not the gear itself, but at the very bottom of the gear assembly nose). We removed about 0.070 inches from the bottom of the nose. In addition, we reduced the outer diameter of the nose by The engine is now equipped with an external vacuum pump and race alternator. MOUNTAIN MOTOR Part V – Finally completed. By Mike Mavrigian 632 Building a

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