THE SHOP

Performance & Hotrod Business - January '15

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8 n PRECISION ENGINE n January 2015 Tighten each rocker shaft hold-down bolt to 25 foot-pounds (with bolt threads Teflon-coated). Again, make sure that the shafts are installed with the series of small oil holes facing downward. Note that you also need to check clear- ance between the bottom of the rocker and the valve spring retainer when the valves are closed. Clearance here needs to be at least 0.010 inches. Setting up a shaft rocker system isn't difficult, but it can require a few hours of adjusting for side clearance due to the stack-up of initial clearances that you may encounter. This will require numerous procedures of measuring, disassembly (in order) and reassembly (in order). It may be a bit of a pain, but a few hours spent adjusting rocker side clearances and valve tip alignment is well worth the effort. The trick is to be patient and keep all pieces (from front to rear of the shaft assembly) in order during disassembly and assembly. (Note: Rocker shaft shims packs are available in thickness of 0.010, 0.015 and 0.030 inches. These are radiused shims that install between the rocker shaft and head in order to raise the rocker shafts. This may be needed to correct for rocker arm geometry if the pushrods are too long or if you mill the heads or block. These are available from several vendors including Mancini Racing and 440 Source.) Water Pump In order to reduce crankshaft parasitic drag and to ensure a constant and reliable coolant flow, I chose a Meziere electric water pump, P/N WP106S, in anodized black, along with a Meziere inlet P/N WP1175S, also in anodized black. The billet CNC-machined aluminum pump features a stainless steel main shaft and ceramic seal, and weighs in at a mere 7.1 pounds. This model fits Mopar B and RB engines as well as Hemis. The pump is rated to flow at 35 gallons per minute, suitable for engines up to 650 hp. A higher-hp engine, or engine running a supercharger or turbo, may require a pump rated at 55 gpm. A wir- ing harness with 20-amp fuse is included. Normal operations draw 6 to 7 amps. Using a Meziere electric water pump offers two primary advantages: no need for a drive belt, reducing parasitic drag on the crankshaft, and a reliable and constant water flow that isn't dependent on crank- shaft rotation. The pump mounts to the front of the block with six 3/8-16 x 1.125-inch stain- less steel socket head cap screws and six 3/8-inch AN washers provided with the pump, and a pair of gaskets. Gaskets are provided with the pump, but we had the option of using the gaskets provided in our Mahle-Victor gasket set as well. I applied a light bead of Ultra-Black Permatex RTV to both sides of both gaskets prior to installa- tion. The water pump mounting bolts are torqued to 25 foot-pounds. Crank Trigger For this build, I decided to take advan- tage of MSD's crank trigger ignition system. This features a reluctor wheel mounted to the crank damper and a stationary (and adjustable) signal pickup sensor. This allows the engine to fire based on crankshaft position, instead of through the distributor, where tolerance variables including potential slop at cam gear lash and the timing chain are now eliminated. While a street engine really doesn't need this (crank trigger systems are most ben- eficial on a race engine), a crank trigger system simply offers a more precise form of ignition timing. With number 1 cylinder at TDC, we then rotated the crank at 32 degrees advance. We then installed the reluctor wheel onto the crank damper so that one of its magnets aligned with the pickup sensor. During the dyno run, we would then be able to make further adjustments if necessary. When installing the pickup sensor (in its adjustable bracket), the threaded sen- sor body allows you to adjust the air gap between the pickup tip and reluctor wheel magnets. And air gap of 0.050 to 0.080 inches is acceptable. We set ours at 0.065 inches. Distributor The MSD Pro Billet 8545 distributor features a centrifugal advance. Since we're running an MSD crank trigger system, we need to lock out the centrifugal advance in the distributor. Remove the advance components including the springs, weights and the advance stop bushing from the advance assembly. You'll need an 11/32-inch open- end wrench to remove the stop bushing's Why mess with a mechanical water pump and belt when you can provide the engine with superior and consistent coolant flow with the use of an electric water pump? Our shop's choice is always a Meziere pump. For this build we chose an anodized black unit. The lower radiator hose neck threads into the bottom of the pump. The pump features a choice of right or left neck positions to suit the builder's radiator neck location. The unused port is sealed with a provided threaded plug. The unit we chose is rated at 35 gallons per minute. The Meziere pump provided a perfect fit to our block, with no modifications needed. We installed a billet aluminum water neck, secured with polished stainless 12-point bolts from Totally Stainless. Our MSD Pro Billet 8545 distributor offers a relatively small diameter head that provides excel- lent clearance to the right side cylinder head's valve cover. The MSD distributor features a centrifugal advance. Since we're running a crank trigger system, we needed to lock out the advance mechanism. The distributor's springs and weights were removed. PRECISION ENGINE

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