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Behind 3-18 day

by Daniel Bennett on

318 engineToday marks the annual recognition of perhaps the most undersung of the Chrysler V8s; while April 26 is celebrated in high spirits, March 18’s “318” V8 was Chrysler’s bread and butter for the better part of 40 years, across three major versions of the venerable motor.

The original “A” engine was introduced in 1957, and continued through the launch of the next generation “LA” (“light A”) V8 in 1967.

The “LA” version lasted until 1992 “Magnum” 318; it was then called the 5.2 (5.2 liters vs 318 cubic inches). The 5.2 Magnum lasted until 1999, where it was replaced by the completely new design 4.7. Its close relation, the 360 or 5.9, lasted a little longer.

Although generally a workhorse long-life motor, the 318 did have a couple of performance variants throughout the years. Starting in the late 1970s, using parts from the closely related four-barrel 360, the 318 recieved its first factory four barrel for police pursuit vehicles. Later, the 5.2 was a performance variant when a FI and roller cam version was used in the Shelby Dakota.

The only major dimensional change across the entire 42 year run of the 318 was in the heads and valve train. The A motors (above) were known as “semi-hemis;” the combustion chamber was similar to a Hemi, and the shaft rocker arrangement was a partially opposed setup, with the intake valve being opened by the pushrod passing underneath the rocker shaft. The LA made the rocker and valve arrangement more symmetrical, but still rocker shaft oriented.

Magnum 5.2 318 V8 engineThe Magnum went to individual stud mounted rockers, along with changing rocker oiling away from the shafts, to the AMC style through-the-pushrod oiling.

In 1997, the 318 had 260 lb-ft of torque at just over 1200 rpm, and kept it there until close to its 4800 rpm redline. Horsepower started out at around 179 at 1200, running up in an almost straight line to over 225 before falling off slightly.

The major short block rotating assembly parts remained nearly identical throughout the whole run, other than balancing. The cranks are physically interchangeable, even though balancing differences make direct swapping impractical. Rod lengths remained the same throughout the run as well at 6.123″, and the bore and stroke remained 3.91″ and 3.31″ respectively.

The 318 is probably the one motor that most every Moparphile has had in their inventory at one point or another, in a car or truck. Rarely associated with the more “glamorous” cars, it was by far and away more common, and plentiful as a result. The 318 is an unsung hero of the Mopar world, as without it, much of Mopar’s reputation for toughness and reliability from that era would not be there.

March 18 celebrates the 318, the li’l engine that could, and did.

Dan Bennett was doomed from the start. His parents bought a 1970 Plymouth Road Runner when it was known that he was coming along, and the rest of the story was written from that point forward.
Raised in a Mopar only home, Dan has also been Mopar only. From ’60s, ’70s, and ’80s muscle to current SRTs of various flavors, Dan has owned, and in many cases raced, each of the Mopar brands.
Dan’s real career is as a “parts guy” at a local dealership, but he also is a muscician, computer geek/gamer, avid reader, and general all around seeker of knowledge. His whole working career has been spent in the parts industry, starting in the aftermarket, and now at the dealership level. He took a couple years off and went in a different direction for a bit as a jewelry designer and salesman, and even though he won a design award for a piece, his true calling, automotive, won out in the end.
He has written articles, or has had vehicles that have appeared in Mopar Muscle, Sport Truck, and Truckin’. In various forums and social media, he has made a name for himself as the “Go-to” guy for tech information for all things Mopar. He also has a large background in many forms of racing and engine building, holding at one point a ASE Certified Master Engine Machinist rating. Though he no longer keeps that certification up to date, he is still very active in the engine building side when he has spare time.
To Dan, there is no option to covering the Mopar world, it is an imperative that must be done to keep his world in balance.
You can contact him at (206) 736-7670.

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