BIG POWER IN SMALL PACKAGES
BUILDING UP THE 360-CID MOPAR SMALL-BLOCK
Building up the 360-cid Mopar small-block
When the subject of most powerful Mopar engines of all time is discussed, the awesome hemi powerplants are sure to be the first ones mentioned. From there, the dialogue generally turns to the torque-laden 440-cid bigblocks most often featuring the legendary Six Pack carb option. All of these are mighty-fine, fire-breathing, axle-twisting engines to be sure.
But in terms of small-block power, the Chrysler La-series engines are often overlooked despite their ability to make good power on reduced funds. The fact is, the small-block Mopar LA engines (318, 340, and 360 cid) were underrated at the factory and were the last of the big three small-blocks offered to the public. Because Mopar engineers could study the errors inherent with other earlier small-block designs, they “corrected” some things with their smallblock and blended in some additional design benefits where possible. Remember the 273 didn’t appear until the 1964 model year and the newly designed small-block 318 (that replaced the larger and heavier Poly 318) came along during the 1967 model year.
The most unique engineering change on the small-block Mopar was the use of solid pushrods and rocker arm shafts rather than the hollow pushrods and individual rockers found on Ford and Chevy small-block engines. The result was excellent oiling, better pushrod and rocker arm rigidity, and no need for valve lash adjustment — simply bolt down the rocker shaft, and the valves are set. And as any racer will tell you, rocker shafts are far less prone to flex, keeping the rocker ratio perfect rocker to rocker and helping head strength as well.
For our buildup, we started with a ’72 360-cid engine taken from a wrecking yard. After checking the block for soundness, we cleaned and bored it 0.030inch over and set about selecting parts from Mopar Performance, Summit Racing, Holley, and others. While the factory 360-cid small-block was rated at 255 hp, we knew that we could certainly beat that target. And although this isn’t a huge-horsepower LA engine, it definitely is a great combination for an everyday driver with good power. Follow along as we show you how to rebuild your smallblock Mopar for improved performance and durability.
The 340 had a six-year production run and was complemented in 1971 by the introduction of the 360-cid engine. While the 360 shared many of the 340’s performance parts, it never got the respect given the 340 because of the fuel and emissions standards that came about during this time period.