550 Horsepower 496 Big Block Chevy

JMacPerformance puts together a budget 496 Big Block Chevy.  The goal is to assemble a pump gas 500 + horsepower,  maximum torque big block on a limited budget.  A SCAT bottom end kit is used a long with –  Comp Cams flat tappet camshaft  –  Brodix Race Rite oval port head  –  Edelbrock Air-gap manifold and  –  Demon 850.


550 Horsepower 496 Big Block Chevy “The Beginning” 

The build starts with a standard 2 bolt main 454 block;  with the usual machine work (bore .030 over, decked, and line honed) a SCAT bottom end kit is installed.  The kit consists of a cast steel crank, 6.835″ connecting rods, KB hyperutectic pistons, Clevite bearings, and a Melling high volume oil pump.



550 Horsepower 496 Big Block Chevy “Heads – Valve train”  

A Comp Cams XE284H flat tappet camshaft and lifters were used a long with Comp Cams push rods, and Crane Cams 1.7 ratio rocker arms.

The camshaft was connected to the crank with a Cloyes double roller timing chain. It was buttoned up with a Cloyes aluminum timing chain cover; the timing chain cover has a built in cam button to eliminate cam walk and a removable plate to allow cam timing changes with out removing the timing chain cover.


Once the cam was degreed with 4 degrees of advance the Brodix Race Rite Oval port heads were installed.  We used the oval port heads to help with the low end torque and because we already had an oval port Edelbrock Air-Gap intake manifold. 



  Once the heads were installed the rocker arm geometry was checked, notice the witness line directly in the middle of the valve stem.

550 Horsepower 496 Big Block Chevy “Carb – Intake Manifold”

  To compliment the camshaft and new heads we installed an Edlebrock oval port air gap manifold. We already had a Demon 850 CFM speed demon carburetor, which worked well with this combination.



550 Horsepower 496 Big Block Chevy “Judgement day”

Not wanting to leave anything up to chance we bolted the 496 to the DTS engine dyno.  After the standard 20 minute break-in of the flat tappet camshaft we did a series of pulls optimizing the ignition timing and jetting.

549 Horsepower and 609 Ft-LB Torque all below 6000 RPM


With 550 + FT-LB of torque from 3000 to 5200 RPM this would make an excellent street engine, especially for a heavy car like a Chevelle or Impala.