Editing Chrysler LA engine (section)

==340 V8<span class="anchor" id="340"></span>==
[[File:Mopar 340er Small Block (23947338547).jpg|thumb|The base {{cvt|340|CID|L|1}} came with a 4-barrel carburetor and produced {{cvt|275|hp|0}} gross]]

In the mid-1960s, Chrysler decided to adapt the {{cvt|318|cuin|L|1}} small block V8 into a lightweight, high output engine equally suited for drag strip or street performance use. Its block was bored out to {{cvt|4.04|in|1}} but its {{cvt|3.31|in|1}} stroke left unchanged, resulting in the {{cvt|340|CID|L|1}} engine introduced for the 1968 model year. Anticipating higher loads resulting from racing operation, the engineers fitted a forged [[shot peening|shot peened]] steel crankshaft instead of the [[Ductile iron|cast steel]] unit used in the 318. This also included shot peened hammer-forged steel connecting rods and high compression cast aluminum pistons with full floating pins. A 4-barrel carburetor was mated to a high-rise, dual plane intake manifold feeding high-flow cylinder heads {{citation needed span|that are still considered among the best of that era.|date=February 2017}} Its big ports used {{cvt|2.02|in}} intake and {{cvt|1.60|in}} exhaust valves. An aggressive cam was fitted to take advantage of the much better breathing top end. The 1968 4-speed cars got an even hotter cam, but it was discontinued for 1969, where both automatic and manual cars shared the same cam. The engine was equipped with hydraulic lifters and two bolt main bearing caps, leading some to initially underestimate the 340's potential. The 1968–71 340's compression ratio was 10.5:1, placing it near the limit of what was possible on pump gasoline during that era. The 340 also used additional heavy-duty parts, such as a double-row roller timing chain and sump-mounted windage tray. Power output was officially stated as {{cvt|275|hp|0}} gross for the 4 barrel.

In 1970, Chrysler introduced a special triple carburetor version of the 340 with triple 2-barrels at {{cvt|290|hp|0}} [[Horsepower#SAE gross power|gross]]. Exclusively called the catchy '''Six-Pack''' on  the [[Trans-Am]] targeted [[Dodge_Challenger_(1970)#The_1970_Dodge_Challenger_T/A|Dodge Challenger TA]] models, the same configuration was used by Plymouth for its Trans-Am [[Trans-Am_production_cars#Plymouth_AAR_%27Cuda|AAR 'Cuda]], called just the "340-6" or "six barrel". This race-oriented version of the already high-performance 340 featured an aluminum intake manifold mounting three Holley carburetors, a dual points ignition system, and a heavy duty short block with additional webbing to allow for aftermarket installed 4 bolt main bearing caps. The application-specific cylinder heads featured relocated intake pushrod passages with offset rocker arms that allowed the pushrods to be moved away from the intake ports, which could improve airflow if the pushrod-clearance "hump" was ground away from the intake port by the end user.

The combination of increasingly stringent [[vehicle emissions control|emission controls]], lowered octane, rising gasoline prices, and insurance company crackdown on high-performance vehicles saw the relatively expensive 340 detuned in 1972 with the introduction of low compression (8.5:1) small valve heads, and by mid-year a cast nodular iron crankshaft and a variety of other emissions related changes. For the 1974 model year, it was replaced by the {{cvt|360|CID|L|1}} engine.

{{hidden begin
|title      = Applications:
|titlestyle = background:#88FF88; text-align:left;
|bodystyle  = text-align:left;
}}
* Chrysler [[Valiant Charger]] (Australia)
* [[Dodge Challenger]]
* [[Dodge Charger (B-body)|Dodge Charger]]
* [[Dodge Dart]]
* 1971–1972 [[Dodge Dart|Dodge Demon]]
* [[Dodge Super Bee]]
* [[Plymouth Barracuda]]
* [[Plymouth Duster]]
* [[Plymouth Road Runner]]
* [[Plymouth Sport Fury GT]]
* [[Monica (automobile)|Monica 560]]
{{hidden end}}