Engine Change Guidelines
OVERVIEW
Engine changes continue to present problems and challenges to car owners and technicians. Here are some tips to keep you and your customers on the straight and narrow.
Our recommendation is to rebuild and reinstall the original engine, transmission, and emission control configuration.
When rebuilding an engine, it must be rebuilt to the original equipment specifications. However, if you do decide to change the engine, these guidelines must be observed to ensure that the vehicle will be eligible for smog certification or registration.
Remember, these are guidelines for performing engine changes – not certification procedures. All exhaust emission controlled vehicles with engine changes must be inspected by an official referee station and must have a Bureau of Automotive Repair (BAR) Vehicle Identification Label affixed to the doorpost.
Remember also, state and federal anti–tampering laws generally prohibit any modification to the vehicle's original emission control system configuration as certified by the manufacturer. And, Section 3362.1 of the California Code of Regulations prohibits any engine change that degrades the effectiveness of a vehicle's emission control system.
CALIFORNIA CERTIFICATION
A federal Environmental Protection Agency (EPA) certified (federal or 49–state) engine cannot be used in a vehicle that was originally certified for California.
CERTIFICATION STANDARDS
Make sure the engine and emission control configuration on exhaust – controlled vehicles are certified to the year of the vehicle or newer, and to the same or a more stringent new vehicle certification standard.
CLASSIFICATION
Don't mix engine and vehicle classifications which will degrade the emissions certification standards. For example, a heavy–duty engine cannot be installed in a light–duty exhaust–controlled chassis even if they have the same displacement. Non–emissions controlled power plants such as industrial or off–road–use–only engines may not be placed in any exhaust–controlled vehicle.
COMPUTER CONTROLS
If a computer–controlled engine is installed in a non–computerized vehicle, the "CHECK ENGINE" light, the Original Equipment Manufacturer (OEM) diagnostic link, and all sensors, switches, and wiring harnesses needed to make the system fully functional must also be installed.
EMISSION CONTROL CONFIGURATION
Mixing and matching emission control system components could cause problems and is generally not allowed. Engine and emission control systems must be in an engine–chassis configuration certified by the California Air Resources Board (ARB) or U.S. Environmental Protection Agency (EPA). The engine must meet or exceed the requirements for the year and class of vehicle in which it is installed.
EMISSION WARRANTY
Voiding the vehicle manufacturer's emission warranty is not allowed.
ENGINE MODIFICATIONS
No internal or external engine modifications (cams, pistons, intakes, etc.) may be performed unless the parts are ARB–exempted or EPA–certified for use in the installed engine. Use the database on this site to search for aftermarket parts covered by ARB Executive Orders.
ORIGINAL EQUIPMENT
The installed engine and host chassis must retain all of their original emission control equipment. Diesel–to–gasoline conversions must have all gasoline engine and chassis emission control systems installed (such as fillpipe restrictor, catalytic converter and evaporative emission system).
SMOG INSPECTION
These vehicles must pass a complete smog inspection (visual, functional, and tailpipe).
If you are ever in LA, let me know, I can meet you at the shop. 
