600 HP 468 Big Block JMac Performance is building a 600 Horsepower street 468 Big Block Chevy engine. As the build progresses I will cover all the details that goes into building a high quality street engine. As our foundation we’ll be using a Gen V four bolt main 7.4L block Pictured below are all the parts that will go into [...]
600 HP 468 Big Block “The beginning” We start our build with a Gen V – 4 bolt main 7.4L (454) block. The block gets fully machined; Hot tanked, magged for cracks, line honed, bored .030 over, and decked to zero deck height The extra casting (flash) is removed and all the threads are individually cleaned with a [...]
600 HP 468 Big Block “Checking bottom end clearances” To insure our 468 will live a long and happy life we need to check all the clearances of the bottom end. We started out by cleaning and deburring all the bearings. This is a step most engine builders delete. I like to verify the quality of [...]
600 HP 468 Big Block ”Bottom end installed” I used the micrometer to check the Forged SRP piston diameter (4.277″) then I checked the cylinder diameter with a bore gauge (4.281″) subtracting the two and we get (.004″) piston to cylinder wall clearance. To insure proper cylinder sealing and minimize oil consumption the ring end gap [...]
600 HP 468 Big Block ”Camshaft and oiling system installed” I buttom up the lower end with the installation and degreeing of the camshaft. I’m using Isky hydraulic roller cam 396282/294. After adjusting the crank sprocket the final resting position for the camshaft is +3 degrees advanced Unlike flat tappet camshafts roller cams rely on backing plates [...]
600 HP 468 Big Block “Heads, valve train, and induction system installed” Before bolting on the heads and valve train I needed to verify the valve to piston clearance. I placed small chunks of modelling clay in the valve reliefs. The head gaskets were installed and the heads bolted in place The rocker arms, lifters, and [...]
600 HP 468 Big Block ”Dyno Testing – Judgement Day” To insure we got all the performance out of our 468 build it was run on a DTS Powermark engine dyno at Saddleback Community College in Mission Viejo Calif. I did an intial 15 minute break-in then a few short pulls to verfy timing and set the air/fuel ratio. After [...]