Serious 340 build into 361 HiRPM Screamer

Small Block Mopar Engine

  1. Locomotion

    Locomotion Well-Known Member

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    One shouldn't get too "rpm happy". Valve float starts before you can actually feel it, like before the car noses over. It's like literally taking a hammer to your valve train.

    A 360 isn't a common high rpm combo, but I ran a W-2 360/727 in a 2,800 lb 2x3 chassis car with a 10.22/131 mph best, Started out shifting at 7200. Tried 6800 and it ran just as fast. Each combo is different, but that's my experience. More isn't always better/faster.
     
    Last edited: Nov 22, 2021
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    • RAMM

      RAMM Well-Known Member

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      I know most people think of a 340 as a high rpm engine but 7000+ and actually making power and being happy there is not pretty normal if we're being honest. J.Rob
       
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      • RAMM

        RAMM Well-Known Member

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        Totally agree-A stable, happy and RELIABLE valvetrain @ 7000+ is not all that common or easy. Most 340's I've tested are pretty much done @ 5900-6000--Will they rev to 7000 rpm if asked to--Yes most of the time. Will they actually keep you pinned in the seat all the way to 7000-7500? Not in my experience they won't. Thanks for the comments. J.Rob
         
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        • gagembassett

          gagembassett Well-Known Member

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          All I'm saying is that I know PLENTY of people that take their 340s to 7,500 and all the up to 9,200 rpm reliably making power up there too
           
        • RAMM

          RAMM Well-Known Member

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          Oh, well I don't know anyone that does that around here-whether its a 350 Chev , 302 Ford or 340. Even our circle track stuff is NorthEAST DIRT Mods are limited to 7600RPM and they are all done by 6700-6800 rpm and lose about 75 HP when spun all the way to the limiter. J.Rob
           
        • gagembassett

          gagembassett Well-Known Member

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          yeah I realize that its very uncommon, I don't know these people in-the-face but I do know them online. .750 solid roller cam and very veryyyy expensive valvetrain helps the 9,200 rpm 340 live. Then again I did forget to specify that is a destroked 340
           
        • rumblefish360

          rumblefish360 I have escaped the evil Empire State! FABO Gold Member

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          I think that’s because of the past yesteryears glory days.
          Now in everyone’s mind they all did that on a regular basis.
           
        • pittsburghracer

          pittsburghracer FABO Gold Member FABO Gold Member

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          Most guys that think their engines run great at 7400rpm have never tried 6800rpm.
           
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          • Bewy

            Bewy Well-Known Member

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            Stroke becomes a player in rpm. And the 340 has a short stroke that favours rpm.
             
          • RustyRatRod

            RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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            ....also nowhere near as easy as it is on internet forums. lol
             
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            • RustyRatRod

              RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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              Problem is, no one really "knows" anybody "online".
               
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              • RustyRatRod

                RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                muh huh.
                 
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                • RustyRatRod

                  RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                  Or it could be because some people are just slap fulla shit.
                   
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                  • RustyRatRod

                    RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                    It kinda reaches the point of diminished returns. I know some friends personally who have some really quick race oriented stuff and never even see 6200. Some of the RPM talked about here is really unnecessary.
                     
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                    • 273

                      273 Well-Known Member

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                      If you got to spin your motor over 6500 rpm especially 7000+ rpm to reach your peak hp goals your probably building too small of an engine.
                       
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                      • jimjimjimmy

                        jimjimjimmy lobsterman FABO Gold Member

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                        do you have a link to this 340 that lives at 9200 rpm .?
                         
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                        • Jeff Seighman

                          Jeff Seighman not my real name

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                          I wouldn't mind seeing that.

                          Jeff
                           
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                          • B3422w5

                            B3422w5 Well-Known Member

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                            Vic Bloomer ran/ runs his 340 around 9,000 rpm.
                            20 over 340 with iron production heads with 1.92 valves, aluminum rods, roller, yada, yada.
                            Its been mid 9’s in a 67 Barracuda at 2700 ish pounds.
                            He broke it few years back, think its back together now, should be out this upcoming summer.
                             
                          • B3422w5

                            B3422w5 Well-Known Member

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                            This is him and car, winners circle in super pro C5AF7B5D-CB72-490B-B406-95F61C80ECD7.jpeg
                             
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                            • jimjimjimmy

                              jimjimjimmy lobsterman FABO Gold Member

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                              i know there is a few super screamers around but there not ''PLENTY''
                               
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                              • pittsburghracer

                                pittsburghracer FABO Gold Member FABO Gold Member

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                                What’s it run and at what weight. And engine details if possible.
                                 
                              • B3422w5

                                B3422w5 Well-Known Member

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                                big, big MPH….making lots of power. Congrats
                                 
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                                • cpearce

                                  cpearce Well-Known Member

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                                  I really don't understand some peoples fetish, or perceived need, to rev their engines beyond the point at which they are providing any return. I swear some people gauge output on sound, not empirical data. Why would you want to unnecessary risk your engine just for the thrill of saying you revved it to some number? Sorry, I don't get it.

                                  For perspective, my Superstock 340 with a very large solid roller, peaked at 6850RPM. I highly doubt many of these street engines are making power anywhere near that high.

                                  @RAMM this is not directed at your build, I think this is very cool and eagerly await the results.
                                   
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                                  • pittsburghracer

                                    pittsburghracer FABO Gold Member FABO Gold Member

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                                    Very nice especially at that weight and NA.
                                     
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                                    • Moparpuller

                                      Moparpuller Well-Known Member

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                                      It all depends on the situation. We truck pull which is basically a drag race with 35.000 pounds behind you. We run the engine to 85-8600 that way when the pan hits it falls into the power at about 7500rpm
                                       
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