my 408 stroker

Magnum Engine Swaps

  1. mopardemon340

    mopardemon340 Well-Known Member

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    • doogievlg

      doogievlg Well-Known Member

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    • mopardemon340

      mopardemon340 Well-Known Member

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      There's only so much I can give. Cam card is posted. Alum Edelbrock heads redecked and valve job, edelbrock rpm air gap intake, special ground cam, special pistons, 770 Holley carb. Motor will handle larger carb it wanted. Runs on pump gas and mid 11s on the track. 904 trans rebuilt by me with A&A parts. All machine work done by CPMotorworks. CPMotorworks - custom performance engine builders
       
      Last edited: Dec 1, 2017
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      • Dartnut

        Dartnut Don't hate me because i'm beautiful

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        So i take it that you are pleased with it?
        Is the point of this thread just a statement of your build, or is there going to be questions and other comments later?
         
      • mopardemon340

        mopardemon340 Well-Known Member

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        Just a statement of my build
         
      • Dartnut

        Dartnut Don't hate me because i'm beautiful

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        Okay, sounds like a good one!
        I've been kicking around the idea of building one, thanks for posting this...........
         
      • doogievlg

        doogievlg Well-Known Member

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        I have my motor out and it is about to head to the machine shop. This build is very similar to what I am shooting for.

        What rotating assembly did you use?
         
      • mopardemon340

        mopardemon340 Well-Known Member

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        Scat rotating assembly
         
        Last edited: Dec 2, 2017
      • autoxcuda

        autoxcuda Well-Known Member

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        You mean Scat?

        What CC dish pistons?

        What was your measured static compression?

        What octane gas are you using with 36 deg total timing?

        Did you do any port or bowl cleanup to the heads?
         
      • CPMotorworks

        CPMotorworks Well-Known Member

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        Scat cast crank and Pro Comp rods, Pistons are custom RaceTecs with -23cc dish @ -.002" deck height, 10.27 static. The Edelbrock heads needed the usual guides sized and valve job corrected, and decks cut as they were not flat and a 64 Ra, so I trimmed them flat and to a 24 Ra. Ports are as cast in keeping with the budget, porting can be done later if Adam and Kevin decide they want more. Fuel was BP 92 octane with 10% Ethanol.
        Camshaft is a shelf Howards HR, 235°/241° @ .050", 110° LSA, .565"/.565".
        What Adam didn't mention is that he or his Dad had never built an engine or transmission before, much less rebuilt a carb. Rookies who were willing to learn and listen to advice. I selected and machined all the parts, measured clearances and degreed cam, measured for pushrods, and they did the rest of the assembly. The transmission Adam tackled by himself other than I pressed some bearings in and out for him.
        I wasn't able to be there for the dyno session or it would have gone a bit differently. Pulls would have started @ 3k and rev limiters wouldn't have been set @ 5400 rpm, and I had a 825 Race Demon on hand for them that was suppose to be tested. But for a pump gas build, on actual fuel from the BP station, driving all the accessories with a serpentine belt, it made decent power.

        AJ 408 #5 HP Values.JPG

        AJ 408 #5 HP graph.JPG
         
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        • doogievlg

          doogievlg Well-Known Member

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          Very nice build and cam selection!

          The 850 cfm carburetor would defiantly help that engine out with that cam.

          This may be a dumb question but I am on the fence about going with a forged rotating assembly or cast. What is a safe hp for cast vs forged? I am shooting for around 500 N/A and I have the budget to go forged but I don’t want to spend the money if it can be better spent in another way.
           
        • CPMotorworks

          CPMotorworks Well-Known Member

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          Not a dumb question at all. The cast steel (vs stock cast iron) will handle that just fine. I haven't used a Scat 4340 crank for this combo yet, but I bet it wouldn't need to have Mallory installed to balance like the cast crank did, even with the light bobweight this one had. So the added cost of the 4340 with less balance work may end up similar to the cast crank with having to add Mallory.
           
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          • myduster360

            myduster360 Well-Known Member

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            Why's that when the engine barely pulled 630cfm on the dyno when a 770cfm Holley was used?
             
          • myduster360

            myduster360 Well-Known Member

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            Looks awesome!

            That magnum PS bracket will hit the battery & tray on an Abody. If your battery isn't in the trunk, a ps bracket off a full sized Van fits much tighter to the block and puts the ps pump in about the same spot as stock. But it would probably require a Dorman A/C delete pulley to keep the belt off the water pump pulley.

            upload_2017-12-2_11-48-52.png
             
          • CPMotorworks

            CPMotorworks Well-Known Member

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            Because there is a big difference in measured wet flow on dyno vs dry flow ratings. Not to mention dyno and track testing shows improvement.
             
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            • mopardemon340

              mopardemon340 Well-Known Member

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              we are looking at a quick flow 850 carb and gate shifter, so we dont keep skipping our shifts on the track.. i think we would have more HP if a larger carb was tested..
               
            • mopardemon340

              mopardemon340 Well-Known Member

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              we made a custom bracket for out battery so we where able to move it and keep it under the hood
               
            • Abodybomber

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

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              That's real world. Nice. I will leave it there .
               
            • doogievlg

              doogievlg Well-Known Member

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              Sucks that you guys are all the way in Wisconsin. I’ll be needing someone to do the machine work on my engine here soon. Awesome build.
               
            • BrianT

              BrianT Let's go!

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              And you'd be correct. I used the forged Scat crank in my 408 and it required no Mallory to get it in balance. Just a little material removed from the weights.
               
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              • autoxcuda

                autoxcuda Well-Known Member

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                I run a scat balanced cast crank 4" stroker rotating assembly. No Mallory.

                Under 500 hp, under 5800 rpm
                 
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