INSTALLATION NOTES:

• Requires addition of carburetor, ignition, fuel pump, and starter (not included)
• 435 horsepower rating achieved during GM testing with high-rise single-plane intake manifold (p/n 809-12496822) and a 770-cfm carburetor with vacuum secondaries (p/n 809-19170093)
• Chevrolet Performance dual-plane intake manifold (p/n 809-12366573) may be used to avoid hood clearance problems, but peak power may decrease by approximately 15-20 horsepower
• Comes with a 12.750 in. externally balanced 153-tooth automatic transmission flexplate. Requires externally balanced flywheel for manual transmission.
• Designed for pre-1976 street vehicles or any off-road vehicle
• Not intended for marine applications

Engine Break-In Procedure

Use conventional or break-in oil (non-synthetic) for the first oil change, be sure to check the oil level in the engine and prime the oil system with an engine priming tool. 

Engines with flat tappet hydraulic cams only - Run the engine between 2,000 and 2,500 RPM's, with no-load on the engine for the first 30 minutes. This is critical to breaking in the camshaft.

Drive the vehicle with varying speeds and loads on the engine for the first 30 miles. Be sure not to use a lot of throttle or high RPM.  Run five or six medium-throttle accelerations to about 3000 RPM (40 to 50 MPH), then let off in gear and coast back down to 20 MPH. Run a couple of hard throttle accelerations up to about 5000 RPM (55 to 60 MPH), then let off in gear and coast back down to 20 MPH.

Let the engine cool and change the oil and filter using conventional (non-synthetic) oil and check the coolant level, top off if necessary. Drive the next 500 miles normally, without high RPMs (below 5000 RPM), hard use, or extended periods of high loading.  Change the oil and oil filter again using conventional (non-synthetic) oil.  Keep an eye on oil levels during the first thousand or so miles.

It would be suitable to use synthetic motor oil after the second recommended oil change and mileage accumulation.

19432114 supersedes 19355722