The back-and-forth movement of the crankshaft is commonly referred to as its endplay. It's measured by positioning the probe of a dial indicator on the crankshaft snout and moving the crank back and forth in the saddle. The thrust bearing and main cap must be installed and torqued to spec before recording this value. Probe accepts no more than 0.009 inch (0.007 inch is preferred) of endplay for all of its small-block engines. Once endplay is dialed, the main caps are torqued to spec (100 lb-ft for the 1/2-inch bolts, and 45 lb-ft for the 3/8-inch bolts on the outside of each four-bolt cap).
These are the lightweight, 5.400-inch, forged I-bean rods and flat-top pistons that are being loaded into our Boss 340. While 0.100-inch 351 Cleveland pistons aren't shelf items at Probe, shop foreman Shawn Mendenhall designed slugs for our bullet that were made in-house, and feature 0.025-inch deeper (intake) valve clearance when we swap the heads/cam/intake package in the second phase of our project. We're using Total Seal's Classic Series race rings to maintain steady combustion inside the Boss 340.
We're building one short -block for two versions of our Boss 340 engine, and its central component is this forged-steel crankshaft. Probe uses a 3.250-inch arm for its popular Street Fighter stroker combinations, which are similar to ours.
This new digital cam-degreeing tool is beyond cool. We got our first look at CamLogic Technologies' digital degree system at the '07 SEMA show, and we knew it would be perfect for this and future engine projects. After getting CamLogic set up, rotating the engine clockwise, and storing BTDC and ATDC values using the system's digital display, the tool accurately identified true TDC for our Boss 340. We then went on to put CamLogic to the true test-degreeing our hydraulic-roller cam-and it performed like a champ. Based on our start-and-stop measuring positions, before and after 0.580 on the intake side, CamLogic's display reads 107.75 degrees, which is almost spot-on with the 108-degrees, which is almost spot-on with the cam card. The procedure is the same for a com's exhaust profile. Sure, the info is attainable with a degree wheel and a calculator, but this tool definitely makes it simple.
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ARP's 2000 Series rod bolts are torqued to 63 lb-ft. |  |
The Boss 340's Comp hydraulic-roller camshaft (PN 35-000-8; grind number FW 3017F/3038F) has perfectly streetable 0.580 (intake)/0.577 (exhaust)lift and 0.236/0.242 duration at 0.050. Since lobe separation measures 112.0 , we think this engine will perform well with a modest shot of nitrous. Prior to installation, the cam is dressed with Pro-Blend assembly lubricant, and the steel distributor gear is given a light coating of moly. | 
Although we considered a timing belt system for our engine, Comp's billet double-roller timing chain (PN 7138)is the setup we're using to squelch excessive valvetrain harmonics. | 
Comp Cams' Pro-Magnum retro-lift hydraulic-roller lifters (PN 8931-16) actuate the 5/16x7.200-inch, 0.080-wall, chrome-moly pushrods we're using for our Edelbrock-headed combo. Due to their length, which can raise clearance concerns, the link-bar-style lifters are installed before the cylinder heads are in place. |