Since the engine in the car we are restoring is not a numbers matching engine, we decided to install a new GM crate engine instead. This “4 bolt mains” engine is very similar to the high performance L82 engine used in the Corvettes of that erra anyway. In fact the camshaft is identical. The L82 used an aluminum intake, so I installed the Edelbrock Performer aluminum intake, and an HEI distributor. The L82 had a 9.0:1 compression ratio (probably because of the flat-top pistons), but the crate 290 has 8.5:1 because of dish pistons, but this should make it easier to use regular pump gas. The heads on this engine are 76cc, and the intake is 1.94″, and 1.5″ exhaust which is the same as the L48. The L82 had 2.02″ intake, and 1.6″ exhaust, but was still 76cc.
In reality, the 290HP SAE gross rating of this engine probably translates to about 230HP SAE net (the 1971 L48 was rated at 270HP SAE gross and 210HP SAE net). The L48 from 1973 was 190HP SAE net, and the L82 High Perf. option was rated at 250 HP SAE net, so this crate 350/290 engine should be in the middle somewhere, as far as performance, between the L48 and L82.
332 ft. lbs of torque @ 3750 rpm
8.5:1 compression ratio.
2 piece rear main seal 4 bolt main
Nodular Iron (1985 and older flywheel bolt pattern.)
Connecting rods-Part # 10108688
Powdered Metal (same rod used in LT1 & LT4 engines, rated for 500 HP)
Pistons-part#12514101
Hypereutectic Cast Aluminum, Dish, with four valve reliefs
G.M. High Volume Pump
Hydralic Flat tappet
Intake Lift-.450″ Exhaust Lift-.460″
Intake Duration @ .050″- 222 Exhaust Duration @.050″- 222
Lobe Seperation-114
This cam Has a mechanical Fuel Pump Lobe.
This is a moderate Torque oriented camshaft.
casting #33417369
1.94″ Intake valve , 1.50″ Exhaust Valve
76cc Combustion Chamber
7 Bolt style Exhaust Flange
Standard 85′ and prior intake manifold bolt pattern.
Perimeter bolt style Valve Covers.
Chevrolet / Chevy Engines:
Rotation: Clockwise
Firing Order: 1-8-4-3-6-5-7-2