This racing manual has been prepared as a guide for the customer who wants added performance or reliability from his slant six. Included are tips covering several different types of racing for all three engine sizes that have been produced to date. The procedures outlined in this manual represent those that have been tested by Chrysler Engineering, working both at the race track and on the dynamometer, as part of its continuing performance development program. This development program serves as the foundation for the Direct Connection parts program.
The slant six engine was introduced in 1960 in two versions - 101 hp, 170 cu. in. and a 145 hp, 225 cu. in. From this modest beginning, the slant six built its reputation for performance and reliability. The 148 hp, 170 cu. in. Hyper Pak introduced in the 1960 Valiant was the next step and the one that was to prove the new engine worthy of any performance challenge.
In 1960 with the introduction of the new compact cars by all the American automobile manufacturers, NASCAR sanctioned a special race exclusively for the little 6 cylinder powered compact cars. The race was held at Daytona and had seven slant six Valiants entered. When the race ended, not only had all seven HyperPaks finished proving their reliability and durability, but they won the first seven places! This type of performance speaks for itself.
The Hyper-Pak option was carried over into 1961 and also made available on the 225; but, 1962 was the beginning of the "big-inch" factory hot rod and the Hemi was coming! The little slant six got lost in the eight-barrel carburetors. The slant six now had to settle for the more mundane job of economical and dependable transportation.
The performance history of the slant six had the usual highlights: four-barrel intake system, high compression pistons, long duration mechanical camshafts, aluminum blocks and one of the first performance four-speed manual transmissions with an in-line six in 1965. But, that was in the 60's and the emphasis in the 70's was fuel economy. Again, the slant six was equal to the task. In 1975 the Feather Duster and Dart Light were introduced to demonstrate the economy of the slant six. This package had a four-speed overdrive and many lightweight body pieces. The slant six responded with an EPA highway number of 36 mpg. This is the best fuel economy turned in by an American 6 cylinder compact.
At the end of the '69 production year the 170 slant six was dropped and in 1970 a new 198 cu. in. version was introduced to replace it. At the end of 1974 his version too was dropped and only the 225 survives.
The three engines share a common bore of 3.4". The 170 engine has a 3.125" stroke; the 198 engine has a 3.64" stroke; and the 225 has the longest stroke at 4.12". Major internal differences between the engines include crankshafts, rods, and camshafts although the camshafts can be interchanged between them.
Year Cubic Inch Bore x Stroke --------------------------------------------- 1960-83 225 3.40 x 4.12 1970-73 198 3.40 x 3.64 1960-69 170 3.40 x 3.125
Note: The parts that were used on the 1960-61 Hyper-Pak six cylinder are no longer available from Mopar or Chrysler Parts and are very difficult to find in general.
Special Note: The Slant Six 225 was dropped from passenger car production at the end of 1983. It is still in production for trucks in 1984.
The slant six engines can be easily identified from other makes because they are slanted over to the right. It has the intake and exhaust manifolds both on the left side and the oil pump, distributor and spark plugs on the right side. To identify one version from another, the engine number is needed which is located on the top right side of the cylinder block toward the front. The number 170 or 225, etc. is stamped clearly along the ledge just below the head. The date that the engine was built and oversize-undersize parts replacement information are also located next to the engine number.
While this chapter covers the slant six engine specifically, other engines such as the "LA" or "B" engine are covered in other engine manuals located elsewhere in this book. There are also racing manuals covering chassis items including transmissions, axles, and front and rear suspensions located in the chassis book P4349341. These manuals do not try to duplicate the service manuals. We, therefore, highly recommend that the correct service manual for your car be obtained before any modification or maintenance is performed.
Next: Parts and Pieces
Slant 6 Index