Plan B 557: Jason Line and Summit Racing Build a 812HP Big Block

The main bearings were pre-fitted with clearances between .0025-.0030 inches—the typical range the team shoots for with its Pro Stock engines. Jason chose an Eagle Specialties forged crankshaft to handle the 812 horsepower and 7,000-plus rpm.

Gen VI blocks are designed to work with one-piece rear main seals, but the Eagle Specialties crankshaft required a two-piece rear main seal. To make the block and crank work together, Jason used a special B&B adapter to give the rear main seal a place to sit. End clearance was set at .005 inches before the main caps were torqued to 105 psi.

Jason chose Diamond pistons, which are used on the team’s Pro Stock engines. The team has its competition pistons vertically gas ported, but for this street-oriented 557, Jason went with lateral gas porting. The gas porting allows cylinder pressure to get behind the top ring and push the ring against the cylinder wall for better sealing.

Jason used a set of Total Seal piston rings. An oil ring spacer was installed because the compression height of the piston caused the wrist pin bore to break into the ring lands. Jason used a fish scale to set the oil ring tension to 11 pounds of drag to keep the engine from oiling or smoking.

The pistons were installed on a set of Eagle Specialties 6.385-inch stroke, H-beam connecting rods. Diamond recommends a .0065-inch piston-to-wall clearance, but Jason elected to go with a tighter .0060-inch clearance to keep the engine running quieter.

The 254-degree intake/270-degree exhaust duration (@.050-inch lift) COMP Cams camshaft was installed and secured with a Jesel front cover. A custom ground, solid roller cam and lifters were used to avoid the high rpm “valve float” sometimes associated with hydraulic valvetrain setups. Cam endplay was set to .005 inches using a set of shims, which come with the cam seal.

Jason opted for a Jesel belt drive system. With numerous dyno runs in store for the 557, he wanted something that was user-friendly and easy to adjust.

The oiling system features a Stef’s standard-volume oil pump and Stef’s aluminum oil pan. The lightweight pan uses a baffle and trap door setup to keep the 557’s oil under control.

Using a bridge dial indicator, Jason found that the pistons protruded from the bore by .005 inches, effectively lowering the deck clearance and increasing compression. Since he was shooting for .046 inches of deck clearance, Jason opted for a set of .051-inch thick Cometic MLS gaskets to increase the deck clearance the proper amount. The result is a 9.8:1 compression ratio.

Jason turned to Trick Flow Specialties for a set of PowerPort 360 cylinder heads. Although the heads flow well right out of the box, Jason couldn’t resist putting his own stamp on the castings. In their off-the-shelf form, the heads have 360cc intake runners and deliver an impressive 365 cfm of airflow.

Using his years of experience with top-end engine components, Jason did his own port work on the heads. He welded material on the intake runner floors, effectively raising the runners by .150 inches. He left the cross sectional areas alone but changed the intake valve angle from 45 degrees to 50 degrees. Once he was finished, the intake runners were still 360cc, but airflow was increased from 365 cfm to over 400 cfm. You can look for Trick Flow to carry Jason’s version of the PowerPort 360 heads in the near future.

For increased valvetrain stability, the rocker arms were welded together—a trick the team uses on its Pro Stock engines.

Trick Flow’s R-Series intake features a single plane design for 500-plus cubic inch engines—perfect for the 557. Jason sent the manifold to Wilson Manifolds, where it was massaged and port-matched to the custom runners he created for the Trick Flow heads.

The Trick Flow intake works with Holley Dominator-style carburetors. Jason’s carb was outfitted with a set of Willys Carburetor and Dyno Shop metering blocks and bolted onto a Wilson Manifolds spacer to enhance airflow and air velocity.

The 557 big block looks impressive—but could it deliver the impressive power numbers Jason was looking for?

The answer: a resounding yes—and then some! Thanks to this Pro Stock-inspired 557, Jason’s 4,500 pound Biscayne wagon has no trouble getting the Line family to the grocery store fast!