Chevy 505ci Big Block Cylinder Heads - Freedom Flow

Patriot Performance's New Freedom Series BBC Heads Deliver On The Dyno

John Nelson Jan 1, 2008 0 Comment(s)

Picking The 'Stick
When it came time to pick a camshaft for this project, we decided to practice what we preach and seek professional help. In short, we told our man at Isky Racing Cams, Nolan Jamora, that we were looking for a street/strip solid roller cam that would give us a big horsepower number but also provide a broad torque band that would lend itself to drivability. The flow bench figures we provided allowed Jamora to tailor the cam to take advantage of the Patriot heads' qualities while also meeting our powerband goals. He recommended a 108-degree-LSA center as the best compromise between power and drivability. "Less would get us more power," Jamora observed, "but it'd be in a quicker range." After reviewing the flow numbers, he came up with lift figures of 0.640 inch intake and 0.650 inch exhaust. "These heads flow well at the top end, so we want to take advantage of that," Jamora explained. The duration figures, 262 degrees on the intake and 272 on the exhaust, were chosen to keep the powerband in a usable rpm range. It'd be an understatement to say we're thrilled with the results. "The cam's not really that big," Jamora summed up. "We got a flat torque band and a good horsepower number, and it's all in a real-world, usable rpm range. The power comes on and stays on for a while." For our part, we'll just say the time taken to match our cam to these new heads was time well spent.

CAMSHAFT SPECS
Manufacturer Isky Racing Cams
Part Number RR-645
Type solid roller
Valve Lift 0.640/0.650 inch,
  intake/exhaust
  (1.75:1 rockers)
Duration 264/272 degrees @
  0.050, intake/exhaust
Lash (hot) 0.028/0.028 inch,
  intake/exhaust
Lobe Center 108 degrees

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