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 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!

60 Responses to 340 Mopar Engine

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  2. DavidStafford says:

    I have a complete fresh 69 275 hp 340 , X heads , AFB carb, original air cleaner down to original exhaust manifolds . Motor came out of my 69 Dart Swinger with a 4 speed . Selling because swapped to a big block .motor. asking 4500.00 obo for all. If interested please text or call me at 815 978 4851..
    Dave. Rockford Il.

  3. Nick says:

    Hello all — I have a completely rebuilt 340 engine for sale if anyone is interested. It is bored .30 over, the entire engine is balanced, has a mild cam, new oil pump, valves, seats, etc.

  4. Johnny O says:

    I need help. Going to look at a 1970 AAR cuda stored for 20 yrs. I’m a mopar guy but not an experienced mechanic/restorer. How do I determine if the motor and trans are numbers matching. Where do I look for the codes on the engine block and trans to tie it back to the VIN and fender tag? Don’t want to pay numbers matching price for older clone. Thanks

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  6. James says:

    I just recieved a 340 block and heads and was just wondering if anyone could tell me or point me in the right way to learn More about it , heres the number off the block 2780930_340.6 and i seen a past post about the head markings between the plugs but all i got are two lines or 11 ? Thanks !

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  8. allan l assam says:

    looking for a 69/340 w/thermoquad

  9. Billy says:

    Had a 69 dart GT Sport back in the day. Many 396 chevelles fell prey to that 340. At one point I ran a 1150 Holley 3 barrel and she took it in stride. Just aquired a 69 Dodge Dart body Gonna build my car again. Have some X heads now looking for a buildable block

  10. JOHN says:

    I have a 340 engine for sale.great condition all painted and brand new gasgets in car running great, 1973 LA engine,any offers?

  11. Frank v says:

    Hi there I have a 73 340 punched 30 over it has the crank, cam, pistons and timing chain installed but that is all the parts I have for it my buddy was building it when he lost his fight with cancer, it’s not been ran since he had it punched over…I’d like to sell it is anyone is interested please let me know

  12. DOUG WHALLEY says:

    I just got a deal on an old bracket race car. I’m told it had a 340 in it. I’m trying to keep it original to the era so if anyone has a 340 even a tired one as long as it is rebuildable I’m interested.thanks so much Doug

  13. demort71 says:

    I tend to agree with your statement that Mopar engines were under-rated. Or possibly the other manufacturer’s motors were often over-rated. I certainly remember mopping the streets back in the mid-70s with my 72 Challenger 318 car. If there was a post 70 small block GM or Ford, they lost to my Hemi Orange Challenger. The only mods my car had was a single Thrush muffler and a set of G60-14 Good Years on the back end. It had a 2.76 economy rear end and Torqueflite. It was a snappy little car. It beat 351 Windsor and Cleveland motors, 350 GMs and the smaller V8s from those camps too. No contest! Mopar or no car!

  14. Kathie says:

    I just became 2nd owner of a 1973 Cuda 340 4 bbl. It had 3384 original miles and has been garaged, the interior still smells new, the car is almost perfect. Original paint, it only needs the carburator which we have located already, it is missing one muffler. It is the 4 speed pistol grip. It is grey in color with silver flecks. Interior – carpet – trunk are all like new. Need to get original wheels which we have located as well. Have the original plates and title.

  15. James Walton says:

    I am interesting in a 340 for my duster

  16. Dalton Jones says:

    as far as the heads. The 340 heads had no adjustments. They were bolt down rockers. So you were limited. But, you could get an older set of 273 heads and rework them with 383 valves. And with the adjustable rockers, you can use different cams.

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  18. Randy creviston says:

    I own a 1970 dodge challenger 95 % restored its black and plumb crazy purple it’s a 4 speed 340 original was wondering what its worth

  19. Dick Wood says:

    Terry Ross, none of what you said is correct. The price is way off,the speed is way off,I don’t know if you are lying or just full of shit but if you are going to try to lie to Mopar owners do some research.

  20. PMANDART says:

    I have a 73 340 block with these numbers on the left side 2760930-340-6 and on the right side of the block 3B3 1807 or 1607…can you decipher that for me?


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