ALL GEN V BOWTIE PRO STOCK BARE BLOCK

Part Number: 24502502

ALL  GEN V BOWTIE PRO STOCK BARE BLOCK - Part Number 24502502
Gen V Bowtie Pro Stock Bare Block Tall deck. This Bowtie block has siamesed cylinder walls and a tall (10.200-inch) deck height that has been the standard for serious Pro Stock and boat racers for years. Features include extra-thick deck surfaces with blind-tapped head bolt holes, priority main oiling, improved coolant flow around the #1 cylinder, four-bolt steel splayed bearing caps, and no mechanical fuel pump boss. Mark IV-style big-block cylinder heads can be used. The Gen V Pro Stock Bow Tie bar block has been the standard for the serious pro stock or boat racer. The Bow Tie block has siamesed cylinder walls, and a two-piece deck surfaces with blind tapped head bolt holes, priority main oiling, no mechanical fuel pump boss, improved coolant flow around the No. 1 cylinder, and inner head bolt bosses. This block also has steel four-bolt splayed bearing caps. Mark IV style cylinder heads can be used on this block. Technical Notes: The Gen V block has provisions for a mechanical fuel pump. Many internal components are interchangeable between Mark IV and Gen V engines, including pistons, connecting rods, camshafts, timing sets, and lifters. External accessories such as water pumps, distributors, intake manifold, and exhaust manifolds are also interchangeable. Chevrolet's new cast iron Gen V Bow Tie block tall deck casting number 24502506 is engineered for maximum-effort racing engines. The "tall-deck" block has a 10.200 in crankshaft-to-deck dimension. Heavy duty Gen V blocks can be indentified by the Bow Tie logos cast beneath the deck surfaces. The water jacket plugs in all Gen V blocks are centered in raised bosses; the 1.625 in diameter soft plugs are interchangeable with small-block and V6/90 Chevrolet engines. The Gen V Bow Tie block uses a two piece crankshaft assembly, seal, and oil pan reminiscent of the Mark IV block. The Bow Tie block differs from production Gen V blocks, which used a one piece seal, and improves the availability of large stroke crankshafts. When using a Mark IV crankshft, engine builders should remember that the cranks is externally balanced and therefore should use only Mark IV type flywheels and balancers. The Gen V Bow Tie block is equipped with four-bolt 8620 steel main bearing caps with 16 degree splayed outer bolt holes on the inner 3 caps. The front and rear caps utilize four straight bolt 8620 steel caps. The rear main cap has provisions for wet-sump style oil systems. Like previous Bow Tie big-blocks, the Gen V heavy-duty block has extra-thick siamesed cylinder walls. Water passages between adjacent cylinders are eliminated to produce extremely rigid cylinder barrels that resist distortion and enhance piston ring sealing. The cylinders are bored to 4.250 in diameter at the factory. The cylinder barrels are cast with a slightly oval-shape to minimize core float and ensure consistent and maximum wall thicknesses for all cylinders. The maximum recommended cylinder bore is 4.600 in, which results in a minimum cylinder wall thickness of .250 in. For maximum effor competition engines. Gen V Bow Tie blocks have inner head bolt bosses cast in, to allow additonal cylinder head retention. This prevents cylinder head "lifting" when used in high cylinder pressure applications. The coolant passages in the Gen V Bow Tie block differ from the passages in both Mark IV and production Gen V versions. Production Gen V blocks have irregularly shaped coolant holes in the deck surfaces; these holes are small and round in Bow Tie blocks. These smaller openings in the decks surfaces improve the integrity of the head gasket seal under high cylinder pressures and reinforce the tops of the cylinder bores to reduce distortion. Competition engine builders can block or resize these round holes by installing threaded pipe plugs. The coolant holes in the Gen V Bow Tie block are smaller than the holes in a Mark IV Bow Tie block. In addition, the hole between the two middle cylinders has been reduced in size and relocated farther away from the lifter valley to improve the head gasket seal. Gen V Bow Tie blocks have an additional hole at the front of the cylinder case. The passage is a vent hole that allows gas to escape during the casting process. If this hole is not plugged, water enginering the block from the water pump can "short circuit" the cooling system by bypassing the block and cylinder head coolant jackets and returning directly to the radiator. These vent holes should be blocked on both deck surfaces to force the coolant to circulate through the engine. Gen V head gaskets do not have coolant holes in this position, and will effectively block the passages. The holes can also be plugged by reaming the cast holes to 3/4 in diameter and inserting soft plugs. Use a length of 5/8 in diameter bar stock to drive the plugs into the blocks so they are flush with (or below) the deck surfaces. All head bolt holes in the Gen V Bow Tie block are blind-tapped. No sealant is necessary on the head bolt threads because the holes do not penetrate the water jacket. Lightly lubricate the threads to produce accurate torque readings when tightening the heat bolts. Both Mark IV and Gen V cylinder heads can be installed on Gen V Bow Tie blocks. However, there are differences in the size and location of coolant passages in the cylinder heads and head gaskets used with Mark IV and Gen V big-blocks. The Gen V head gasket blocks the large coolant passage at the end of the cylinder head; a Mark IV gasket leaves this passage open. Mark IV head gaskets may be used on a Gen V block if the coolant passages in the front of the decks are plugged. Due to changes in the water passages, there is a possibility of coolant leaks into the lifter valley if Gen V head gaskets are used with Mark IV cylinder heads. A Mark IV head gasket may not seal the larger coolant holes in the Gen V cylinder heads properly. To forestall sealing problems, Mark IV and Gen V head gaskets should be used only with their respective cylinder heads. The lifter bosses in the Gen V Bow Tie block are larger than the bosses in Mark IV Bow Tie and production Gen V blocks. These oversize bosses allow an engine builder to install larger diameter lifters after boring out the tappet bores. The lifters can also be relocated to optimize valvetrain geometry by offset boring the lifter holes. The front bulkhead of a Gen V Bow Tie block is moved forward .300 in compared to a production Gen V block. This change improves coolant flow around the No.1 cylinder in the Bow Tie block, which has larger cylinder barrels than a production casting. Both single-row and double-row timing chains will clear this bulkhead. However, if a Jesel belt-type system is installed on a Gen V Bow Tie block, the back of the Jesel aluminum cover must be machined for clearance. The tall deck Gen V Bow Tie blocks weighs 288 pound, which is at least 12 pounds lighter than imitation aftermarket blocks. Oiling System The main oil gallery in all Gen V blocks is located alongside the camshaft tunnel. This oil gallery location allowed the installation of splayed-bolt main bearing caps and the ability to machined the oil pan rails for additional crankshaft clearance without the risk of breaking into the main oil passage, which was a concern on Mark IV blocks. The main oil gallery diameter of Gen V Bow Tie blocks is 9/16 in. The Gen V Bow Tie block has a "priority main" oiling system, which was developed for use in the legendary ZL-1 aluminum big block. Drilled passages carry oil directly from the main oil gallery to the front four main bearings. (Oil for the rear main bearing is routed from the oil filter outlet). Oil is supplied to the camshaft bearings in a gen V big-block through passages drilled from the lifter valley. These passages intersect the cam bearing bore tangentially, opening an oval "window" approximately 1/2 in long and 1/4 in wide. When installing camshaft bearings in a Gen V block, the oil hole in the camshaft bearing must be aligned with this opening. The oil hole in the bearing insert should be at the 2 o'clock position as the main oil gallery in a production Gen V block. Material has been added to the Bow Tie casting to allow engine builders to enlarge this passage. However, if the diameter of the main gallery is increased, its centerline must be relocated to prevent breaking into the lifter bores. The hone over-travel reliefs at the bottoms of the cylinder bores are squared-off to maximize bottom end strength. The main bearing bulkheads are fully machined. The Gen V Bow Tie block has provisions for a dry sump oil inlet line. The oil passage at the rear of the block above the bellhousing flange can be drilled out to the main oil gallery and threaded for a 1/2 in NPT pipe fitting. Oil from the presure stage of the dry sump oil pump can be directly into the main oil gallery through this hole. The integral connections production Gen V blocks have for external oil coolers are omitted on Gen V Bow Tie blocks so that plugging of these passages is not required. In addition, the boss for the integral connections has been removed from the block to reduce weight and improve assembly time. Material was added to the bottoms of the cylinder barrels in Gen V Bow Tie blocks to increase strength and to accommodate large cylinder bore diameters. In some instances, the bottom of the No. 8 cylinder barrel may interfere with the distributor gear. (This is not a problem in production Gen V blocks, which have smaller cylinder barrels). Any interference can be easily corrected by chamfering the bottom of the distributor gear or grinding additional clearance in the block. Some aftermarket distributors have O-rings on the distributor shaft that seal the passenager's side lifter oil gallery. Because of the size of the camshaft tunnel in the Gen V block, these O-rings may both actually seal the distributor hole. This can be checked by pre-assembling the engine and verifying the position of the O-rings in relation to the distribtuor hole. The position of the distributor in the block can be adjusted if necessary by machining the distributor pad on the intake manifold (to lower the distributor) or adding spacers between the distributor and manifold (to raise the distributor). Note: 2003 engineering changes added provisions for product roller camshaft.
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