BIG POWER IN SMALL PACK­AGES

BUILD­ING UP THE 360-CID MOPAR SMALL-BLOCK

Mopar Muscle - - Contents - TEXT AND PHO­TOS: CAM BENTY

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.

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