ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Small Block Mopar Engines

Updated on February 25, 2014

The un-Chevy...

Building a great running small block Mopar is easy - as long as you know what parts to use and have a machine shop that's knowledgeable about the finer points of Mopar power. Running a small block Mopar also makes a statement. Nothing against Chevy, but they're more than a little... overdone. To see what I mean, just go to any big car event - say Hot August Nights. You'll see TONS of Camaros, tons of Tri-Fives, lots of Chevelles and Novas, and most will be powered by the ubiquitous small block Chevy - most likely a 350 with the obligatory Edelbrock dual plane intake and a Holley carb. If it's a really crappy day, you might even see a Ford Mustang or a Plymouth Barracuda "powered" by a small block Chevy (stop for a minute to ponder just how wrong that is). If you want something that really stands out you need a Mopar. If you are thinking about building a Street Machine, don't just go with the flow. Think Small Block Mopar.

318 Polysphere Engine
318 Polysphere Engine

Pre-history of the Small Block Mopar

Before there were LA's there was the Polysphere...

In 1967, a 318 version of the LA engine was introduced. It soon replaced the 273 as Chrysler's "bread and butter" V-8 choice. Saddled with low compression and a factory 2 bbl limit for most of it's production span, it never gained a performance reputation. Properly modified, though, it is easily capable of producing 375 to 400 streetable horse power. It also has a well deserved reputation as one of the most reliable engines ever produced.

How to Build Big Inch SB Mopar Engines

 

In the Beginning - 1964 - birth of the LA-series Mopar small block...

1964 Plymouth Barracuda
1964 Plymouth Barracuda

(Image: Yzukerman under Creative Commons)

The modern small block Mopar (aka the LA - for Light An engine) was introduced in 1964 with 273 cubic inches and made its debut in the Dodge Dart and Plymouth Valiant. The new LA engine was based on the earlier A engines and most short block components will interchange. The new small block Mopar cylinder heads were quite different though - smaller, lighter, and with a wedge-shaped combustion chamber. The LA engine was about 50 lbs lighter than the earlier A engine and only about 50 lbs heavier than the Mopar Slant Six.

Rebuilding the Small Block Mopar

 

Mopar 273 ready to be rebuilt
Mopar 273 ready to be rebuilt

The Mopar 273

The small block Mopar LA engine family began life in 1964 with 273 c.i., a 2 bbl intake system, and 180 HP. In 1965, a 4 bbl version was introduced. Besides the 4 bbl carb, it also featured higher compression and a hotter cam, producing 235 HP. An even hotter version was available in 1965, producing 245 HP with the help of a solid lifter cam, 700 cfm Holley carb, and factory steel tube headers. In 1966, a special version of the 273 was available in the "D/Dart" producing 275 horse power. No other production Chrysler small block achieved the magical 1 HP/cubic inch - not even the vaunted 340.

Building a Mopar 273 today would almost have to be a labor of love. The main problem with building a 273 is the lack of affordable pistons. A set of cast, low compression pistons for the 273 will cost about $300 if you can even find them (by comparison an equivalent set for a 318 or 360 only runs around $100). An alternative would be custom forgings which cost $800 and up - more than most people would want to spend, especially on an economy type rebuild.

Built 318 Small Block Mopar
Built 318 Small Block Mopar

The Mopar 318

In 1967 Mopar introduced an LA small block with 318 cubic inches. The Mopar 318 soon replaced the 273 as Chrysler's "bread and butter" V-8 choice. Unfortunately the 318 was saddled with low compression and a 2 barrel carburetor for most of it's production life, so it never gained a reputation as a performance engine. Properly modified, though, the 318 can easily make 375 to 400 streetable horsepower.

In my opinion, the 318 is the bast all-around small block Mopar. Its small displacement means you can get great gas mileage, but it's big enough to make good power. It also has a well deserved reputation as one of the most reliable V8 engines ever made. If you are looking to build an engine that puts out 300 to 375 horsepower, the 318 is probably your best choice. Cores are easy to find and cheap, aftermarket speed parts are easy to find, and lots of people know how to get good power out of it.

Small Block Mopar 340 Six Pack
Small Block Mopar 340 Six Pack

The Mopar 340

The Mopar 340 was introduced in 1968 and instantl became Chrysler's premier performance small block. The 340 came with a 4 barrel carburetor (it was never offered in 2 barrel form), forged steel crankshaft, 10.5:1 compression ratio pistons, and was factory rated at 275 horsepower. It reached its peak of development in 1970 with the 340 Six Pack, a special version featuring 3 Holley 2 barrels mounted on an Edelbrock aluminum intake manifold that made 290 horsepower. The Six Pack only lasted 1 year and was only available on the AAR Cuda and Challenger TA. In 1972, compression was lowered to 8.5:1 with power dropping to 240 horsepower. In 1973 (the last year of production) the forged crank was replaced with a cast piece. The 340 can be built into an excellent performance engine but it's almost impossible to find a good core because of the low production numbers.

Small Block Mopar 360
Small Block Mopar 360

The Mopar 360

The Mopar 360 started life as a "smog motor," but after 340 production stopped it took over the small block performance mantle for Chrysler. While it always had potential, it never offered what could be considered excellent performance from the factory. It makes a great foundation for a hot street engine, though. With careful aftermarket parts selection and good building techniques, it can be made into a very strong runner.

Rebuilding a small block Mopar is just as easy as building any other American V8 engine - as long as you have the right information. How to Rebuild the Small-Block Mopar (S-A Design) has everything you need to know about rebuilding small block Mopar engines. It covers both LA series small blocks and the later Magnum engines. If you're rebuilding a small block Mopar, this book is a must-have.

Block Selection

Choosing a solid engine block...

Picking a small block Mopar engine block isn't as easy as other makes. The first thing to consider is engine mounts. The 273 and 318 blocks use different engine mounts than the 340 and 360 blocks. Also, some time in the early 1980s Chrysler changed the engine mount style. If you're running a different year or displacement block than what your car came with, chances are you'll have to buy or fabricate adapter mounts. Not a deal killer, but something to be aware of. The other thing to be aware of is that earlier blocks tend to be cast a little thicker and therefore are a bit stronger. Early blocks can take a 0.030" overbore, but later blocks should be limited to 0.020". I know from experience that the mid-80's and up 318 blocks are prone to cracking between the center head bolt hole and the water jacket. It is an easy repair, but adds about $100 to your machine shop bill. Earlier blocks don't have this problem, and I don't know if the Magnum engines do.

Small Block Mopar Heads

The key to high performance...

Up until the 302 and 308 "high swirl" heads, small block Mopar heads were basically junk - at least for high performance. If you're on a budget, the bast factory LA_style heads are the 302 and 308 castings that came on mid 80's 318s and 360s. Magnum heads work even betterm but you'll also have to change your entire valve train, intake manifold, and valve covers to convert an LA engine to Magnum heads. It would be easier and cheaper to buy a set of aftermarket heads from Indy Cylinder Heads. For an in depth discussion of small block heads, check out the following link...

Please Sign my Guestbook - I appreciate all comments and feedback

    0 of 8192 characters used
    Post Comment

    • opatoday profile image

      opatoday 

      5 years ago

      This is just Amazing Thank You

    • profile image

      anonymous 

      5 years ago

      How about Poly's

    • mowug1776 profile image

      mowug1776 

      5 years ago

      great article, I've often wondered about putting a 440 or 426 hemi in 1964 barracuda ( just for kicks). I have two different styles of 318 in.³ one in 1977 Dodge halfton and the other in a 1964 one ton. I also have a 77 half ton with a 360. All three are great engines. At this point I am trying to restore all three so that they are operable. Although I do love the large block Mopar. My 77 with the 318 gets roughly about 20 miles to the gallon highway.

    • profile image

      anonymous 

      5 years ago

      @glenbrook: and he wants $500 for it!

    • profile image

      anonymous 

      5 years ago

      @glenbrook: this is what the ad says.i hope hes right!Factory 4 barrel intake manifold for 277, 301, 313, 326 and early (wide block) 318 Mopar engines from 1956 through 1966. These engines are also referred to as a Poly or Polysphere.... thks for the help glockr

    • glenbrook profile imageAUTHOR

      glenbrook 

      5 years ago

      @anonymous: If the 4-bll intake is for the poly 318 it will fit. If it's from an LA engine it won't.

    • profile image

      anonymous 

      5 years ago

      i have a 66 coronet with a factory 2 barrel poly motor,will a factory 4 barrel intake fit with no problems and all intake ports will line up?thks

    • glenbrook profile imageAUTHOR

      glenbrook 

      6 years ago

      @anonymous: With stock cam and compression ratio, around 600 cfm would probably work better. What intake manifold are you running?

    • profile image

      anonymous 

      6 years ago

      I have a stock 1990 360 tbi,converted to carberation, 518 trans..It came out of a 1990 dodge ram350 1 ton van lwb. what do you rcomend for a proper fit on the cfm for this engine. we are having tunning diffaculties with an edelbrock 750 (1411). seams to large to us. the chassis is a 1995 ram 1500 ,

    • profile image

      SoutheastCylinderHead 

      6 years ago

      Good article, you definitely know about MOPAR Engines. The 340 six-pack was an unsung hero on the street racing scene when I was much younger.

    • mistyblue75605 lm profile image

      mistyblue75605 lm 

      6 years ago

      Nice subject. Thanks for the info...squid liked and completed my quest! lol :)P

    • glenbrook profile imageAUTHOR

      glenbrook 

      7 years ago

      @joanhall: Thanks Joan, I really appreciate it.

    • joanhall profile image

      Joan Hall 

      7 years ago from Los Angeles

      Your lenses are an excellent example of using Squidoo to write about what you know and share your knowledge with like-minded people. Even though I know zilch about cars, I'm giving this lensography an Angel blessing and will feature it on my SquidAngel At Your Service lens.

    working

    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, hubpages.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://hubpages.com/privacy-policy#gdpr

    Show Details
    Necessary
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Features
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Marketing
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Statistics
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)