340 Mopar Engine

The 340 Mopar Engine is still one of the most popular Mopar Engines from the ’60s and ’70s. Some Mopar Engines were designed for drag racing. They were heavy and bulky, but put-out high horsepower. This made them great for straight line races, but anything that involved curves they struggled. That’s were the quick-and-nimble 340 Mopar Engine found its calling.

The 340 Mopar Engine was developed in the 1960s and found its way to production by the end of 1967. It was close in cubic inches to the 318 Engine, but they differed in a whole lot more than just 22 cubic inches.

The 340 had: high performance heads, special carburetor and cam; New oil pump with a 90 degree adapter; 2.02 inch intake valves and 1.60 inch exhaust valves; Dual Time Chain with windage tray; high-rise dual plane intake.

Even with all of these performance features the top “horsepower rating” that any 340 Mopar Engine was 290 horsepower. This was the 340 Six Pack version debuted in the Dodge Challenger T/A and AAR ‘Cuda. Many believe that many Mopar Engines’ horsepower were underestimated to cut down the costs that buyers would have to pay for their insurance. So the actual horsepower of these 340 engines are most likely more than the rated 290 horsepower.

Stock 340 Mopar Engine Characteristics


Figure 1: Stock 340 Engine Horsepower & Torque Curves

Figure 1 show the performance characteristics (power curve) of the stock 340 engine.  The maximums were at 281 hp at 5200 rpm and 328 lbs/ft at 3900 rpm.  These numbers are right on target for the the factory ratings on the 340 high performance which were 275hp at 5000 rpm, and 340 lbs/ft at 3200 rpm.

Share Your 340 High Performance Modifications

How have you built up your High Performance 340 Engine? Share in the comments!

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57 Responses to 340 Mopar Engine

  1. david sutton says:

    will a 340 fit in a97 dodge dakota

  2. david sutton says:

    Will a H.P 340 fit in a 97 Dodge dakota

  3. ray says:

    I have a 1973 sm. block 360/2bbl carb/with 340 heads from factory complete motor and 727 trans from the a/c pump to trans yolk with 51,000 act.miles and all paper work. Motor was taken out of Dodge camper. This is a number one motor/trans. Motor has no ticks/knocks/pings or smoke and trans shifts very nice. Removed valve cover to look at cast numbers, looked like new.I got this for a small truck project but 8 months later due to health reasons I must sell, so anyone reading or looking at this post who has a project for mopar or no car this is a nice set up for you and I feel at the price of 800.00 dollars is better then fair. Sorry no pictures that are good. Motor is sitting on trailer under shed coverd with bags and rags so if you are looking /want or just need to have, you can contact by email(lintonray62@yahoo.com) or (910)381-2161 and ask for Crazy Ray. Please no calls after 10 pm. Thanks. 800.00 dollars is a nice price for a nice set up so remember if we have need for speed only MOPAR will do! Located in Eastern NC. Also available, 1987 727 4-speed automatic trans.

  4. frank says:

    what might the rated horsepower for a 1972 plymouth roadrunner be?…it says its a 340 Hi Performance…the stock ones are rated at 240 hp….this Hi Performance engine has a single 4bbl carb

  5. bill matson says:

    I have a 71 340 but not sure what heads are on it. There is no x or j markings btn plug holes but has AAWJ markings on the top. Have not located any numbers on top and haven’t pulled the head either. Can someone help?

  6. steve o says:

    I have a 71 340. Totally cleaned and honed block and cylinders. New rings and bearings. Stock pistons. Comp cam .565. Edelbrock air gap dual plane. J’heads resptinged to match cam. New valves mild porting and bowl hogged. A demon 750 and msd ignition. Light weight water pump aluminum rad and electric fan. Anybody know what kind of numbers it might pull on the dyno. It is in a 67 barracuda

  7. steve k says:

    just acquired my sister’s ’69 dart 340 swinger after years of hoping they would give up while sitting in their ca. back yard. not ran since ’84. will be starting the restoration. all stock all #’s matching. 90 k on odo. 1st question has x heads. were they considered higher performance heads than any others for that year?

  8. DAVID says:

    I READ THE THE O HEADS WERE THE 6PAK 340 HEADS SOMEWHERE IN MY RESEARCH. I HAD BOUGHT A 70 340 CUDA # MATCH AND IT HAD O HEADS AND THIS WAS THE ANSWER I FOUND FOR THE O CAST HEADS. ALSO IVE SEEN MANY ADDS FOR 340 ENGINES ON E BAY LISTED AS TA/AAR MOTORS BECAUSE THE CASTING # SAYS 340-6. I ALWAYS THOUGHT THE – # WAS HOW MANY CORES IT TOOK TO MAKE THE BLOCK?? I READ THIS IN A CHRYSLER ENTHUSIAST MAGAZINE MANY YEARS AGO. DOES ANYONE KNOW WHERE I CAN DOCUMENT THIS?

  9. mike says:

    Terry Foss is full of shit! #11

  10. Randy says:

    I have duster with a 340 4barrel carb. And a pistol grip. 4 speed car is pretty close to perfect condition how do you know if it has matching #s and what kind of carb. Randy

  11. Randy says:

    I have a 340 4 barrel carb duster how do i know if it has matching # s it’s a 1970 car

  12. Ada says:

    I tend not to write many remarks, however i did a few searching and wound up here High Performance 340 Mopar Engine.
    And I actually do have 2 questions for you if it’s allright. Is it just me or does it look as if like some of these comments appear like they are written by brain dead individuals? 😛 And, if you are writing at additional social sites, I would like to follow everything new you have to post. Could you make a list of all of your shared pages like your twitter feed, Facebook page or linkedin profile?

  13. Bill D. says:

    Whats differance between x and j heads?How can I find out how my 68 340-s Barracuda came equiped without fender tag.Vin # doesn’t give a lot of info.

  14. Mark says:

    Hi I’ve got a T/A 340 block .030 over
    X heads
    Crane Cam 528lift
    13.1:1 compression running 100 octane
    headers
    pro comp intake
    only 600 cfm carb (now)
    4500 convertor
    car ran 11.49 @107mph BUT ran 7000rpm 3/4
    way down the track ..geared to high 4:89
    I put this motor in my street car with 3:91
    350lbs heavier and pulls great just never made it back to the track…but would love to know my horsepower

  15. Charles Hearne says:

    I owned a 1970 Dodge Dart 340 swinger, Hemi Orange with black interior. Bought the car in 1973. Graduated in 1975 from high school, and sold it that year. I hated that decision even today. The car did not have power steering, or A/C, no power brakes. Not even a radio from the factory. Only a cigarette lighter. I added an eight track tape player. 275 hp is a joke. That car would, from a 30 mph punch take your breath away. If you tried to floor it from a standstill it would just smoke the tires.

  16. angel martinez says:

    I bought a 1966 plymouth barracuda and it has a 340 mopar engine with casting numbers 2780930. culd you let me know what make and year it is? my can text it to me if you coud… 609 339 2174 thank you

  17. Mark says:

    I have a bare 340 block I believe it’s a 1968, plus heads and other parts I may be interested in selling. If interested e-mail me and I’ll get back to you. I also have a 1968 Plymouth Barracuda 4-speed w/factory air which needs resto and is apart I’m thinking of selling. Thanks Mark

  18. ROB says:

    I HAVE 1963/64 PLYMOUTH CHRYSLER CARTER AFB 4 BARREL CARBURETOR’S. I BELIEVE THEY ARE THE FRONT AND BACK CARBS. I WANT TO SELL THEM ASAP, MAKE ME AN OFFER. THANKS ROB

  19. ROB says:

    ALSO HAVE A 1966 STOCK 383 FOR SALE. SEND ME EMAIL AND CAN SEND PICS. THANKS

  20. Brent Edwards says:

    In need of a 340 for my 1973 dodge challenger. Does anyone know where I can get my hands on one.

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