Classic Cubes From An LS1 Part 1

This shot is of the crank's rod bearing fillets. The stock unit's filletjournal (left) is recessed and prone to cracking where the ballpoint penis pointing, whereas the Lunati crank's fillet (right) is a moretraditional, rounded design for added strength.

The factory rods (left) are a powdered metal construction featuringcracked caps and a pressed-pin design. Due to the construction methodsemployed, resizing of the big end of the rod isn't feasible as it limitsthe choice of available bearings, with no performance or race bearingsoffered. Stock rods are fairly stout but insufficient forhigh-horsepower applications. The rods weigh 650 grams and have a lengthof 6.098 inches. In contrast, the Lunati Pro-billet steel rod is of"barrel-shaped beam" construction and features a full-floating pin andbronze bushings on the small end of the rod. Weighing 630 grams andfeaturing Lunati rod bolts, this rod is lighter, longer (6.125 inches)and rated to 1,100 crankshaft horsepower for continuous use. Clearancingof the block on all cylinders due to the longer stroke is necessary atthe bottom of the block and liners. Additional clearancing on connectingrods 1, 5, and 7 is necessary, because the cap screw in the rod wouldtouch the cam where the screw comes through the rod. All materialremoval is done to achieve a minimum of 0.050 clearance and is performedby hand. The MTI 455 H.O. is the only MTI block/liner stroker enginecombination that requires extra clearancing.

The factory pistons (left) are a hypereutectic design featuring apressed-pin and no valve reliefs. Antiscuff coating is present on theside skirts, but no thermal barrier coating is applied to the pistontop. The piston weighs 434 grams and utilizes a 1.5mm moly top-ring, a1.5mm cast-iron ring, and a 3mm stainless oil ring. Although it is agood factory piston, a weak spot is the piston crown, which is subjectto destruction from detonation. The Wiseco forged-aluminum pistons aremanufactured to take upward of 750 crankshaft horsepower. They feature afull-floating pin, valve reliefs, and a 14cc reverse dome. Athermal-barrier coating protects the piston top, while an antiscuff,antifriction coating runs the length of the skirt. The piston is custommade to fit the 4.160 bore size, and the pin location has been raised toreduce compression height to accommodate the longer stroke and rods.This piston uses a file-to-fit Total Seal 1/16-inch ductile plasma molytop ring, a cast-iron 1/16-inch second ring, and a standard-tensionstainless oil ring that measures 3/16 inch. Weighing in at a scant 420grams, this piston is ready to rock.

Before beginning the rotating assembly installation, the main caps areremoved and the block is thoroughly cleaned using hot water and Tidedetergent. All block bolt holes are cleaned and tapped to ensure theywill take the specified torque. The holes are sprayed with WD-40 toresist corrosion before assembly begins. Clevite H-series main bearingsare used with the ARP main studs tightened from the innermost out. Thecenters and outers are torqued to 60 and 50 ft-lb respectively, whilethe side bolts are torqued to 19 ft-lb. MTI looks for 0.0025-0.003-inchclearance on the main bearings. Clevite Bearing Guard is used forlubrication to avoid metal-to-metal contact at startup. (Note that thispicture shows the rods installed--ignore that part).

The Lunati rods and Wiseco piston combos are installed by using a Childsand Albert tapered ring compressor with a 4.160-inch diameter. Childsand Albert assembly lube is used to lubricate the rings and cylinderwalls. The combination is gently pushed into the cylinder.

Here, all eight pistons are installed. Each rod was carefully slippedover the crank's rod journals, ready for rod cap installation.

Clevite H-series rod bearings are used on all MTI's engine packages.After installation, the ARP bearing cap bolts are torqued to 70 lb-ft.MTI looks for 0.0018-0.0020 inch clearance on the rod bearings.

With the Durabond cam bearings pressed back into the cam journals, theMTI custom ground cam is lubricated along with the cam bearings, withClevite Bearing Guard. The MTI G-1 cam was specifically designed for the455 H.O. engine package and features 228/232 degrees duration at 0.050with 0.588/0.574 lift (with 1.70 rockers) and a 113-degreelobe-separation angle.

Once the cam is in position, it is retained with a cam retaining plateand four bolts. The bolts are torqued to 22 ft-lb.

Two shims are used to space out the oil pump in preparation for thewider Rollmaster double timing chain. Each Rollmaster featuresTorrington bearings for excellent reliability and silent operation. Thecam is degreed using a cam-degree wheel utilizing the intake centerlinemethod to ensure accurate timing events.

Here is an RA-7-equipped GTO.

See the sidebar for details on the RA-7 package.