Chevrolet Performance ZZ572/620 Base Engine 621 HP @ 5400 RPM

INSTALLATION NOTES:

• Clutch linkage boss is now drilled and tapped. When using cast-iron exhaust manifolds, lower head bolts may need to be replaced with bolts with shorter heads, for clearance
• Gen VI tall-deck block has machined mechanical fuel pump boss
• Comes with a 14'' automatic transmission flexplate. Requires internally balanced flywheel for manual transmission applications
• 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 break 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 letting off in gear and coasting back down to 20 MPH. Run a couple of hard throttle accelerations up to about 5000 RPM (55 to 60 MPH), then letting off in gear and coasting back down to 20 MPH.

Let the engine cool and change the oil and filter using conventional (non-synthetic) oil and check coolant level, top off if necessary. Drive the next 500 miles normally, without high RPM's (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 level 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.