Need advice racing a 380 horse crate engine

Discussion in 'Mopar Performance Issues' started by 500duster, Sep 8, 2018.

  1. 500duster

    500duster Well-Known Member

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    I got out of racing 8 years ago and sold most of my racing stuff. went to the track a few weeks ago just to watch and got the urge to race again. I figured my 67 barracuda notchback street car would be a good choice to race in the street class and keep things affordable. The car has full interior, all steel except a fiberglass hood. The engine is a mopar performance 380 horse crate engine with a 750 vacuum secondary carb, doug's headers, pertronix 3 ignition set at 35 degrees total advance all in by 3000 rpm. trans is still fully automatic 727 from 727 specialist with an 11 inch 727 specialist converter advertised 2400 -2600 stall. rear is 81/4 with 3:55 and a new sure grip unit. I run 28 inch tall tires on street but I have a set of 26 x 8.5 slicks so I put those on thinking it would help the effective gear ratio. I ran the car this past week and the car hooked well, never missed or popped or hesitated but the best time was only 14.21 in the 1/4. 60 foot times were 2.05. 1/8 mile times were pretty consistent 9.16 to 9.18. it made no difference leaving the car in drive and letting it shift itself at 4500 or shifting it manually at 5700. I know I need a better converter but I want to keep the car drivable on the street and would like to keep the 3:55's. I have been told switching the m1 intake to an edlebrock air gap would help. I know for bracket racing the car just needs to be consistent but it would definitely be more fun if I could get into the low 13's or high 12's. What do you guys suggest? I should mention the car has 21/2 inch exhaust with flowmaster 40's that dump at rear axle.
     
  2. replicaracer43

    replicaracer43 Old school member

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    Buy a converter custom built for the car and you'll be fine. What was you trap MPH
     
  3. Plymouth 65

    Plymouth 65 Floorable Deplorable

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    3000 stall, 3:91 rear should help. You need to know where max torque/horsepower vs. RPM. There's a big difference between a street car and a race car. You have a great street car setup, race car not so much! 65'
     
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    • 500duster

      500duster Well-Known Member

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      best mph in 1/4 was 95.34 best 1/8 was 78.34
       
    • jimjimjimmy

      jimjimjimmy lobsterman FABO Gold Member

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      your mph might be a little low I was guessing 108 to 110 a stock 340 duster will do 98 to 100 mph . do you know your weight ?
       
    • replicaracer43

      replicaracer43 Old school member

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      MPH is way low, you might have tuning issues too, but the converter will make a huge improvement
       
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      • 500duster

        500duster Well-Known Member

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        Not sure of weight. no scales at track I was at. should weigh close to what a stock 67 barracuda weighed but I've checked for stock weights online and seen variations from 2700 to 3400 pounds. I would think 3400 would be more accurate.
         
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        • jimjimjimmy

          jimjimjimmy lobsterman FABO Gold Member

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          at 3400 lbs and 380 hp is 12.09 @111.76 Acconding to Wallace
           
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          • jimjimjimmy

            jimjimjimmy lobsterman FABO Gold Member

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            according to Wallace your making 231 hp . at 3400 lbs
             
          • Garry in AZ

            Garry in AZ Building a 9 second Valiant FABO Gold Member

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            Your car may not have as much power as you expected... from the numbers you posted, that would mean about 225-250 HP.
            My buddy has a Cutlass that weighs about 3600 pounds. The car dynoed at 400 RWHP. He has a 3600 rpm stall converter. His car runs pretty consistently in the mid to high 12's at a bit over 100 mph. A higher stall converter would very likely help your times, and launch the car harder.
            Half the fun is chipping away at the ET, play around with it and just have fun!
             
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            • 500duster

              500duster Well-Known Member

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              I checked those numbers before I went to the track and was obviously disappointed when I got my 1st time slip. I have heard 3:91 gears work best with the 380 horse crate engines so I wasn't expecting a 12 second pass but thought for sure it would run in the lower 13 range. I'm not sure lower gears and a converter will get me anywhere near 12.09. When I had my 73 pro street cuda I switched from an off the shelf 10 inch converter to a custom built 8 inch ati and picked up about .6
               
            • jimjimjimmy

              jimjimjimmy lobsterman FABO Gold Member

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              are you sure the secondary's are fully opening with that vacuum carb ?
               
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              • 500duster

                500duster Well-Known Member

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                I an not sure but have been wondering about that. This engine has less than a thousand miles on it so to be that down on power there has to be something going on. I just put the lightest advance springs in the distributor so I will have 35 degrees total all in by 2000 rpm next thing of concern will be the carb. what is best way to check opening of secondaries? I have used a twist tie on rod before to check for movement.
                 
              • Abodybomber

                Abodybomber Breaking street machines , since 1983.....:)

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                380 crate was recommended with a 750 double pumper.
                 
              • jimjimjimmy

                jimjimjimmy lobsterman FABO Gold Member

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                I bet a 4150 750hp would wake it up .
                 
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                • thesiren74

                  thesiren74 Well-Known Member

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                  You should be well into the 13s, i ran 14.02 @101 with my old 360 and 2.45 gears. And with 3.23s and a 3500 converter i ran best open headers 13.05 @105.
                   
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                  • thesiren74

                    thesiren74 Well-Known Member

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                    I shifted at 6grand also.
                     
                  • jimmer

                    jimmer Well-Known Member

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                    I think an intake change for sure.
                    Also what version of 380 crate motor do you have ?
                    I believe the cam is a 292/501 hydraulic cam or a roller cam that is close to that ?
                    I think you are short shifting ?
                    Both camps should pull a bit more then 5700 for sure .
                     
                  • jimmer

                    jimmer Well-Known Member

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                    As for converter I would call Dynamic .
                     
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                    • AJ/FormS

                      AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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                      Gears are a really big deal.
                      There is nothing you can bolt on to your engine (short of supercharging it ), that will touch 10 or more percent gear.
                      And getting the engine up to where the power is, is probably just as important.
                      Leaving the line with an 11" 2500TC and a 7.88 corrected starter gear means the engine will not get to where the power begins until about 36 mph, might peak at 44mph, might shift at 50 mph. That is a really really long pull.
                      And 14.2 seconds is about 93 mph, so you are gonna trap around; 6500 in second, or at 4500 in third, and that means you only went thru the power peak 2 times and/or are either waaay over the power peak at 6500,or waaaay under at 4500.
                      So I guess you have some tough decisions to make.
                       
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                      • rumblefish360

                        rumblefish360 so close yet so far away

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                        The guys make good points. AJ hit it well.
                        The engine can be capable but your car is heavy and I’m betting it has a full interior as well. I have seen this engine run 12’O’s with a few into the 11’s. Of course they were Dedicated race cars. They were got it out, no interior, fiberglass parts upfront.

                        A converter and gear change will do wonders ET wise. Next is the cars weight and body stiffening.

                        How far do you want to take it?
                        Oh! MP also suggest 1-3/4 headers IIRC.
                         
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                        • Hysteric

                          Hysteric Well-Known Member

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                          Before you spend any money i suggest you tune what you have. As other posters have mentioned your mph is low considering what you have.

                          You're missing power somewhere its just a matter of looking to see where it is.

                          Make no assumptions and check everything.

                          Hysteric

                          Great looking car by the way.
                           
                        • 500duster

                          500duster Well-Known Member

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                          Is that the dynamic converters by Frank Lupo? if I remember correctly there are 2 different dynamic companies.
                           
                        • jimmer

                          jimmer Well-Known Member

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                          Yes Frank Lupo .
                           
                        • 500duster

                          500duster Well-Known Member

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                          It is the roller cam version