L31 Truck Engine
ATK Core Return Process
JEGS and ATK appreciate your business and want to ensure that your core return is as smooth as possible.
- Core return must be a 1996-2000 350ci Vortec Truck/SUV engine
- Factory Specs
- Horsepower: 255 hp
- Torque: 330 ft.-lbs.
- Horsepower: 290 hp*
- Torque: 375 ft.-lbs.
*Carbureted engine was tested using a performance dual plane intake manifold, 670 cfm carburetor, and an HEI distributor.
- 1996-2000 seasoned OE block
- 2-bolt main
- 1-piece rear main seal
- Passenger side dipstick
- Displacement: 350 ci, 5.7L
- Crankshaft: OE reground cast 1 piece seal
- Balance: External rear, internal front
- Rods: OE reman powder metal 5.7 in.
- Compression Ratio: 9.6:1
- Pistons: Cast
- Rings: Moly
- Camshaft: Hydraulic roller
- Cam Duration @ .050 in.: Intake 191 / Exhaust 194
- Cam Lift: Intake 0.414 in. / Exhaust 0.428 in.
- Lobe Separation Angle: 112 lsa
- Timing Chain: Single roller
Cylinder Head Information:
- Cylinder Heads: Vortec cast iron
- Combustion Chamber: 64 cc
- Intake Runner: 165 cc
- Valve Size: 1.940 in. Intake / 1.500 in. Exhaust
- Rocker Arms: Stamped steel 1.5
Oil Pan Information:
- Oil Pan: Black 4 quart
- Oil Pump: Melling standard volume
Long Block Includes
- Short Block
- Timing Set
- Cylinder Heads
- Valve Covers
- Timing Cover
- Oil Pan
- Oil Pump & Pickup Tube
Notes: Does not have mechanical fuel pump provisions.
Engine Break-In Procedure
Use conventional or break-in oil (non-synthetic) for the first 600 miles of operation. Do not drive for long periods at any single speed, always vary your speed. Do not tow a trailer or put other heavy loads on the vehicle. Check the engine oil and coolant levels daily.
At 600 Miles change the engine oil and filter using conventional (non-synthetic) oil. Check fuel and ignition settings; adjust valves (where applicable).
After the first 5,000 of service synthetic engine oil may be used. Follow your vehicle owner’s manual for service intervals.
Start Fresh with a Drop-In Replacement Crate Engine
JEGS crate engines are reverse engineered to create a product that has better-than-new quality. Reverse engineering allows any factory original defect to be found and removed; saving you time and money by keeping your vehicle out of the shop and on the road. Engines are factory checked after assembly to ensure proper operation. JEGS crate engines feature a 36 month/unlimited mileage warranty.
This engine was designed as a direct replacement for 1996-2000 Chevy & GMC pickups, SUV's, and van applications. These vehicles introduced the L31 5.7L small block featuring Vortec cylinder heads that were developed for maximum power and efficiency. Producing up to 255 hp in factory spec, this engine can also be retrofitted into an older car with a performance carburetor to produce up to 290 hp.
Do you need to break these engines in or are they ran before hand
How many quarts of oil do these hold
would this be the best engine to replace a engine for a 1999 chevy tahoe 8th of vin is a R
Are these heads able to accept 1.6 roller rockers without modification? I’m trying to get a little more lift out of the cam, but want to make sure the pushrods won’t rub on the cylinder heads.
What are the head and cam specs? I am looking for the size of the runners in the heads.
Are these new or re-manufactured blocks and parts? If i use this in place of a 305 will i have to replace the computer?? and the injectors???
Part# 059-0282 can u install higher cam and lifers and how much more it's going to be price wise
why is this not emissions legal?! if connected to an 2000 express 1500 vortec motor with headers short ram intake and chip tuned ?
WARNING: Motor vehicles contain fuel, oils and fluids, battery posts, terminals and related accessories which contain lead and lead compounds and other chemicals known to the State of California to cause cancer, birth defects and other reproductive harm. These chemicals are found in vehicles, vehicle parts and accessories, both new and as replacements. When being serviced, these vehicles generate used oil, waste fluids, grease, fumes and particulates, all known to the State of California to cause cancer, birth defects, and reproductive harm.
WARNING: Some dust created by power sanding, sawing, grinding, drilling, and other construction activities contains chemicals known to the State of California to cause cancer and birth defects or other reproductive harm. Some examples of these chemicals are: lead from lead-based paints, crystalline silica from bricks and cement and other masonry products, and arsenic and chromium from chemically treated lumber. Your risk from exposure to these chemicals varies, depending on how often you do this type of work. To reduce your exposure, work in a well-ventilated area and with approved safety equipment, such as dust masks that are specially designed to filter out microscopic particles.
WARNING: The wires of these products contain chemicals known to the State of California to cause cancer and birth defects or other reproductive harm. Wash hands after handling.