The 4.0 inch bore family
350 variations 1967 to 1980
The L-48 is first available in the Chevy Camaro for the 1967 model year as the high performance engine option. This version was then an option in 1968 for the Nova and then in 1969 the engine is also available for the Impala’s, El Camino as well as an export product for the Holden in Australia from ’69 until 1972. In ’69 the L-48 package includes a Hydraulic camshaft, four barrel carburetor, cast pistons, and four bolt main bearings. The block has 010 as the casting number while the heads have either 041 or 186 casting identification number. This engine develops 300 hp and will offer 380 lb-ft (520 N-m) of torque. The compression due to the EPA mandate is lowered to 8.5:1 for the ’71 model year. From 1975 until 1980 the Corvette had the 350 L-48 V8 as the basic engine which produced 165 bhp (123 kW) for the ’75 model but it increases to 180 bhp in’76 through ‘77. By ’78 California and high altitude areas the L-48 offers 175 bhp while other areas the same engine will develop 185 bhp (138 kW). For 1979 the HP rating goes up to 195 but drops back to 190 bhp for the 1980 model year. By 1972 the Nova SS is the only other model with the L-48 four barrel and the car can be confirmed as an original factory Nova SS L-48 if the fifth character in the VIN is a “K”; ’72 is also the only year that a Nova SS pack can be identified with the VIN number.
The 350 cu in (5.7 L) LM1 package develops 155 to 175 hp is available in most Chevy passenger vehicles through to the 1988 model year. The four barrel carburetor is generally a Rochester Quadrajet and could be had with points, electronic and/or computer controlled power distribution through-out the years. The two barrel variation of the LM1 350 is the L65 which develops 145 hp; these two 350’s are superseded by the L05 for the 1989 versions.
From 1970 to ’74 the basic engine in the Corvette is the ZQ3 small block 350 with the four barrel Rochester 4MV carburetor, hydraulic lifters and 10.25:1 compression developing 300 bhp. The main bearing of the ZQ3 is the first 350 with the larger 2.45 journal. There is apparently a lower nickel content in small blocks cast after 1971but the deck is thicker to compensate while the heads are lighter with less iron in the casting but as a result they are more likely to crack than their predecessors-these units also have a lower compression of 8.51:1 which equates to a lower 270 bhp (201.34 kW) with the torque also dropping to 300 (net) lb-ft as well. In 1972 the ZQ8 will deliver 200 bhp net (149 kW) with 270 lb-ft torque; in ’73 an additional drop to 190 bhp (141.68 kW) although the 1974 model year the horse power rating goes up slightly to 195 bhp.
350 variations continued…