Small-Block Mopar History and Tips

Steve Dulcich and David Freiburger sit down to plan a small-block rebuild for a 1970 Dodge Challenger after its factory 318 got wrecked in a prior Roadkill Garage episode, and the conversation turns into a full history lesson on Chrysler’s LA-series V8. Viewers in the comments call it some of the best pure engine-nerd talk on the channel, right down to warnings about mixing cast and forged cranks. It is dense, it is technical, and Mopar fans cannot get enough of it. Watch to see what they land on for the rebuild.

An engine does not usually become the main character of a show, but when Steve Dulcich and David Freiburger start geeking out about the LA-series small-block Mopar, that is exactly what happens for several unhurried minutes. The pair are elbow-deep in a 1970 Dodge Challenger project after its factory 318 got destroyed during a prior Roadkill Garage episode, and instead of just bolting in a replacement and moving on, they pause to trace the entire lineage of the engine family, the changes, the trims, the versions serious Mopar people still argue about at swap meets decades later. One commenter joked it is as hard to follow as a lawyer talking to an accountant. Judging by the replies below, plenty of viewers followed along anyway, and loved every minute of it.

A 1970 Challenger, and an Engine That Did Not Survive

The starting point for this whole conversation is a car in real trouble. The 1970 Dodge Challenger at the center of this Roadkill Extra segment lost its factory 318 small block during a previous Roadkill Garage episode, forcing Dulcich and Freiburger to step back and plan a proper rebuild rather than simply dropping in whatever engine happened to be sitting around the shop. That pause is exactly what gives this particular segment its shape: rather than rushing straight to wrenching, the two hosts use the moment to walk through decades of small-block Mopar history first, treating the rebuild as an excuse to properly understand the platform before committing to a direction for it.

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The LA-Series Small-Block: Chrysler’s Answer to the Small-Block Wars

The LA-series small-block, LA standing for Lightweight A, was Chrysler’s direct answer to the small-block wars raging through Detroit in the 1960s. It debuted in 1964 at 273 cubic inches, a genuine departure from the earlier polyspherical A-series engines it replaced, and grew over its long production run through 318, 340, and eventually 360 cubic-inch versions as Chrysler chased more displacement and power to keep pace with Chevrolet’s 283 and 327 small blocks and Ford’s own small-block Windsor family. Understanding which version sits under a given hood, and which year it came from, genuinely changes what a build like this one is even capable of.

Why the 340 Gets Special Reverence

Among Mopar people, the 340-cubic-inch version gets a level of reverence the plainer 318 rarely receives, and one commenter’s story about a 340 Dart makes clear why. Factory-equipped with better-flowing cylinder heads than the smaller-displacement versions in the same family, the 340 punched well above its displacement class in period performance testing, holding its own against considerably bigger engines from rival manufacturers. A well-sorted 340 Dart or Duster remains one of the more respected sleeper builds in Mopar circles specifically because the factory heads already did half the performance work before an owner ever touched a wrench.

Cast vs. Forged: The Detail That Trips Up Builders

Buried in the comments is a genuinely useful build warning that deserves repeating: do not mix cast and forged cranks and harmonic balancers when assembling one of these engines. It sounds like a small detail, but cast and forged components carry different specifications and tolerances even when they appear physically interchangeable, and mismatching them during a rebuild can lead to premature failure or vibration issues that are difficult to diagnose after the fact. It is exactly the kind of hard-won knowledge that separates a builder who has actually torn down a dozen of these engines from someone working purely off a shop manual.

The 318’s Long Second Life in Trucks

Another commenter mentions a 1992 Dodge Dakota running a 318, a detail that points to a less glamorous but genuinely important chapter of this engine family’s story. The LA-based 318, evolved into the Magnum-updated version along the way, soldiered on in Dodge trucks and vans for decades after its passenger car heyday had faded, well into the 1990s and beyond. That long truck-and-van service life is part of why parts for these engines remain so widely available and affordable today, a direct legacy benefit for anyone restoring or hot-rodding an older A-body Dart, Duster, Barracuda, or Challenger now.

Why Roadkill Extra Exists

Roadkill Extra exists as a specific kind of bonus content: free bonus footage designed to preview MotorTrend’s paid Roadkill programming for viewers who have not yet subscribed. Rather than a tightly produced segment, it leans on genuine unscripted engine-nerd conversation between two hosts who clearly enjoy talking shop with each other, letting tangents about engine history run their natural course instead of cutting away to keep pace with a strict runtime. That looseness is precisely what makes it work as a preview, since it shows exactly the kind of chemistry and depth that keeps Roadkill’s full paid episodes worth subscribing for.

What Serious Mopar Builders Take From This

For anyone seriously restoring or hot-rodding an A-body Dart, Duster, Barracuda, or Challenger today, knowledge like this is not just trivia, it directly informs real build decisions. Knowing which displacement and head combination a given block started life with, whether cast or forged internals are appropriate for a target power level, and how later truck-service parts interchange with earlier passenger car versions can save a builder from expensive mistakes before the first bolt ever gets turned. That is ultimately why a segment ostensibly about fixing one broken engine ends up functioning as a genuinely useful primer for an entire generation of Mopar small blocks.

That is really the throughline connecting every tangent in this segment: history is not being recited for its own sake, it is being used to make a better decision about a real engine sitting on a stand in front of two hosts who have to live with whatever they choose next. Viewers picking up a wrench on their own A-body project get the same benefit secondhand, learning from a conversation that treats decades-old engineering choices as directly relevant to a build happening in the present. That is worth more than any single spec sheet could offer on its own.

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