Chevy Engine Block - Cutweight Horsepower

Swapping a Cast-Iron Block for an Aluminum One on a Chevy Small-Block V-8

Mark Stielow Sep 1, 2006 0 Comment(s)
Sucp_0609_07_z Chevy_engine_block_swap Main_oil_passage_plugs 2/22

The First-Generation Chevy small-block V-8 design has many press-in plugs in the iron block, but on the aluminum Bow-Tie version, these Allen plugs are used. When final installing, these main oil passage plugs should have their threads coated with Loctite 592 thread sealer/lock and installed to quarter-turn past hand-tight. The threaded holes between each lifter set are drainbacks that require stands to prevent high amounts of oil pouring on the cam and crank.

Sucp_0609_08_z Chevy_engine_block_swap Pistons 3/22

This shot gives an idea of what it looks like to run 18-degree cylinder heads-the oversize, straight-on intake port requires the intake valve lifter pushrod seat to be offset 0.150 inch to create room for the oversized intake ports. The Arias dished pistons are asymmetrical to exactly match each cylinder's chamber shape-so make sure you mate them up to the correct hole.

Sucp_0609_09_z Chevy_engine_block_swap Combustion_chamber_view 4/22

The CNC-machined combustion chamber on the Dart (PN#14172121) cylinder heads offer fully CNC-machined surfaces with 2.15 intake/1.625 exhaust stainless steel valves. Notice how the valves have been machined on the backside of the head to remove material-this reduces weight and allows for a slightly smaller combustion chamber to maximize "squish" area on the sides of the chamber (that results in power).

Sucp_0609_10_z Chevy_engine_block_swap Lifter_bores 5/22

The offset Crower Super Duty hydraulic roller lifters are set into the lifter bores of the Bow-Tie block after being soaked in a bucket of oil for a while (to fill the cavity in the hydraulic lifter). Before each pushrod is installed, W2W adds some #3 high-pressure lube to the tip of the pushrod.

Sucp_0609_11_z Chevy_engine_block_swap Main_and_head_studs 6/22

The Bow-Tie block can be ordered with a full set of head and main studs, or you can get a set from ARP. These ARP 7/16-inch thread (one end fine, the other end coarse thread) head studs are being installed to 100 in/lbs. This torque is essentially "hand-tight" and can be accomplished by using the "two open-end wrench" method as shown here. There are two head studs in the center of the head that "neck down" from 7/16 inch to 3/8 inch (they go between the Siamesed intake ports). W2W suggests you use the head gasket bolt holes as a guide to where to put these studs in the block. Notice the Fel-Pro head gasket installed after wiping the block and cylinder head surfaces off with lacquer thinner.

Sucp_0609_12_z Chevy_engine_block_swap Intake_port 7/22

The Dart CNC-machined intake port is a work of art. Notice how the valve-stem guide is molded into the overall shape of the port (arrow)-that helps to make power. Also, the light vertical lines (arrows) are from W2W's "port-matching" activities. They measured the intake manifold port width is equal to or less than the port width of the cylinder head-this keeps flow at a maximum through that area.

Sucp_0609_13_z Chevy_engine_block_swap Pushrod 8/22

The length of the 3/8-inch-thick Manley pushrods were determined with the use of the T&D-provided valvetrain geometry tool. This tool shows when the rocker stands are shimmed to the proper height with the correct length the pushrod.


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