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How to know if what cam for 427W?

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  • How to know if what cam for 427W?

    Hey Fellas,
    Yeah, it's me again....asking about the 427W that is still on my mind...... I've been reading some and it seems that some folks claim that a 4.17" throw crank in an OE 351W block would require a "reduced-base circle camshaft"........ so my questions are:

    -- How can I tell if I truly need one or not?
    -- If so, is it a bad thing or not?

    Ryan
    Quality means doing it right when no one is looking. - Henry Ford

  • #2
    I would assume rod selection would dictate how much clearance you would have. 383 Chebbys require a reduced base circle cam, especially when running an H beam. If you go with a billet cam core, unless you're going huge with the cam, I don't see where you would run into a problem but maybe Dennis can stop in here and offer more insight.
    1965 Poppy Red Three Peddle Gear Banger
    347 Stock Block Pump Gas Street/Strip 10.44 @ 125.97 Old Combo
    363 Dart Block Pump Gas Street/Strip - 10.11 @ 133.17 so far

    2005 Torch Red Topless Three Peddle 12 valve Monster
    244 Stock Block Pump Gas Street /Street Much Slower


    Current CI Count - 103

    Comment


    • #3
      Originally posted by Poppy65 View Post
      I would assume rod selection would dictate how much clearance you would have. 383 Chebbys require a reduced base circle cam, especially when running an H beam. If you go with a billet cam core, unless you're going huge with the cam, I don't see where you would run into a problem but maybe Dennis can stop in here and offer more insight.
      Ok, that makes sense...... Thanks, Poppy!

      The 427W package in question was built with 6.125" Ultralight I beam rods......so sounds like it could handle a standard 'base circle' camshaft. How can you tell if a cam has a billet core? I doubt it would be a "huge" cam, as it would likely have a 6500 redline, since the build is based on a stock '69 FoMoCo-casting 2-bolt main 351W block.

      As far as headers that can deal with the 0.5" higher ports of the TFS 5240---4 -CNC R-Series heads, I believe Ford Powertrain Applications has them.....

      Ryan
      Quality means doing it right when no one is looking. - Henry Ford

      Comment


      • #4
        IIRC, early 4,170 stroke used a 6.250" rod that needed clearancing at the big end of the rod for the cam (which was based on a reduced circle for additional clearance.) If the package you are looking at has 6.125" rods, that doesn't necessarily mean that the rods need less clearancing. It means the piston pins are .125" lower to compensate for the reduced rod length. Since stroker rods typically use the Chevy big end diameters so that part would still be the same. There would be a slight angle change of the rod though. Clearancing is not supposed to be a big deal, but it involves more work than the other strokes as your swinging a larger throw. Any decent machine shop should be able to do it and its all about the combination that is being used. For example capscrew rods often offer better clearance that normal type that use a bolt and a nut-this is not necessary a firm rule.

        I would suggest contacting the supplier of the kit in question and get their thoughts and your chosen machinist who is doing the clearance work. If you can get a hold of Woody at http://www.fordstrokers.com/ he will give you his professional thoughts on the matter. I'm 99% sure he'll recommend the 408w as the best all around choice for most builds. (My Dart block 434 uses the same 4" stroke crank.)

        When it all comes down to it the overhead valvetrain is one of the weakest links in any such motor. Racers go to great lengths to stabilize it using billet core cams, larger studs, stud girdles or shaft rockers, larger diameter pushrods, roller rockers, better quality (expensive) valve springs, etc. As far as the reduced circle cam, it does the opposite and will offer more flex to the vale train in extreme situations than a standard Ford designed diameter circle cam would. Although it may not really an issue for a grocery getter type motor, during 6500 rpm shifts I am not really so sure its such a good idea. You pay your money and you take your chances . . . .

        You will also find that there is a limited amount of "off the shelf" reduced circle cams variations available for purchase. IIRC, most seem to be designed for a street motor.
        Dennis

        65' STANG Street/Strip

        434W NA, Victor Heads, Super Vic Intake, Bullet SR, Braswell Carb, 11.2:1, Gforce 4 Spd, 4:33, 93 Octane Pump Gas pushing 3550lbs. 9.91@135.56

        Comment


        • #5
          We put a billet small base circle cam in my brothers nitrous huffing 383 and spin it to 7,400 and haven't had an issue...yet. Guess we'll see long term but I would guess your cam guy is going to give it a go/no go before he even grinds it if it's going to be a concern.
          1965 Poppy Red Three Peddle Gear Banger
          347 Stock Block Pump Gas Street/Strip 10.44 @ 125.97 Old Combo
          363 Dart Block Pump Gas Street/Strip - 10.11 @ 133.17 so far

          2005 Torch Red Topless Three Peddle 12 valve Monster
          244 Stock Block Pump Gas Street /Street Much Slower


          Current CI Count - 103

          Comment


          • #6
            Originally posted by Dennis112 View Post
            Since stroker rods typically use the Chevy big end diameters so that part would still be the same. Yep, this build is proportedly a PROBE rotating assembly with a 4.17" forged crank and 6.125" rods swinging on 2.10" (same size as chebbies) rod journals.

            Any decent machine shop should be able to do it and its all about the combination that is being used. This build has already been partially assembled...less an intake, cam, timing cover and oil pan.

            .....capscrew rods often offer better clearance that normal type that use a bolt and a nut-this is not necessary a firm rule. Yep, it is assembled with capscrew rods.

            I would suggest contacting the supplier of the kit in question and get their thoughts and your chosen machinist who is doing the clearance work. I didn't purchase the PROBE pieces or have the machine work done.

            .....the 408w as the best all around choice for most builds. Yeah, this build is already too far along to back down to a 408W.

            Although it may not really an issue for a grocery getter type motor, during 6500 rpm shifts I am not really so sure its such a good idea. You pay your money and you take your chances . . . . The 6500 RPM shift limit is only based on 'bench talk' of what is relatively safe with a stock 2-bolt main block.
            Thanks, Dennis!

            Ryan
            Quality means doing it right when no one is looking. - Henry Ford

            Comment

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