Need help with scavenged 406

Discussion in 'Engine Topic' started by Harold Cox, Feb 23, 2021.

  1. Harold Cox

    Harold Cox New Member

    Messages:
    3
    Likes Received:
    0
    Joined:
    Feb 22, 2021
    Location:
    Crossville Tennessee
    Basically Im concerned about performance.


    I have a zz4 long block I could use but I was hoping for more from a 406.


    Wasn’t that impressed with the zz4.




    So here is what I have for the 406 build.


    Heads? I have a nice set of 461's with 64cc chambers, 2.02/1.60 in good shape with hardened seats and drilled for 400 steam holes with screw in studs. Not the 461X


    But Im concerned that they may not allow enough air in and out and that with the 64 cc chamber I may be pushing my CR for 93 octane.




    I would like to use the parts I have simply because of economics but if its not going to perform then I need to make changes.




    I could spring for a set of heads…Not vortec please. Something aftermarket.




    Heres a list of what I have


    406


    Bore:4.125


    12.5 cc dish piston


    5.7 eagle rods with apr blots


    Stock crank


    Dual-plane performer intake


    750 double pumper


    Double timing chain and gears


    Rotating assembly balanced.


    Block has not been decked






    Summit Racing Part Number:CCA-CL12-239-3
    Hydraulic flat tappet


    Duration 262/270


    Lobe separation: 111 deg.


    RPM Range:1,300-5,600


    Intake Valve Lift 0.462 in.


    Exhaust Valve Lift 0.480 in.


    But I have a few sets of 1.6 / 1.5 roller rockers if needed.


    Grind Number:CS X4 262H-11




    Im curious about the torque and horsepower with this set up and the performance I can expect.




    Built power glide


    3:36 10 bolt


    1966 Chevelle




    Thanks.
     
  2. 1320feet

    1320feet Veteran Member

    Messages:
    295
    Likes Received:
    112
    Joined:
    Oct 23, 2019
    Location:
    Calgary, Alberta.
    Keep your 461 heads. I get 10.05 comp ratio using 64cc chamber, 12.5cc piston, .039 felpro head gasket and piston down the hole .025. It will make great low end torque with that cam. I don't worry about tight quench. It's not as important as most on the internet think.
     
    sooner likes this.
  3. Harold Cox

    Harold Cox New Member

    Messages:
    3
    Likes Received:
    0
    Joined:
    Feb 22, 2021
    Location:
    Crossville Tennessee
    Thanks!
     
  4. G72Zed

    G72Zed Veteran Member

    Messages:
    2,376
    Likes Received:
    1,043
    Joined:
    Sep 8, 2015
    Location:
    Canada
    If your at a 4.125 bore, your at 400.9 cubic inches and not 406, and to hit a 10:1 CR @ 400.9 ci you need a total of 91cc @ TDC. I would not trek higher with that iron head on pump gas, even more so if your un-decked and piston to head comes in @ .064 like 1320feet states, not to mention the PG.

    Those 461 heads come in around 1.8-1.85 sq in at the pinch, and with a 2.02 and good valve job your approx. in the 210-220 cfm range +/-.

    Looking at the specs, your HP will peak around 5k rpm or so, and you will have very good TQ down low to match up with the PG's 1.76 1st and 3;36's.
     
  5. Harold Cox

    Harold Cox New Member

    Messages:
    3
    Likes Received:
    0
    Joined:
    Feb 22, 2021
    Location:
    Crossville Tennessee

    I'm sorry. bore is 4.156 (400 30 over)
    Thanks! Great info!
     
  6. 1320feet

    1320feet Veteran Member

    Messages:
    295
    Likes Received:
    112
    Joined:
    Oct 23, 2019
    Location:
    Calgary, Alberta.
    That jumps comp ratio to 10.18.
     
  7. G72Zed

    G72Zed Veteran Member

    Messages:
    2,376
    Likes Received:
    1,043
    Joined:
    Sep 8, 2015
    Location:
    Canada
    In that case you have a 407 cubic inch and you need 92.5cc @ TDC to hit 10:1 CR.

    Adding this up, with a 12.5cc -dish, 64cc chamber, .5cc crevice volume and a 9cc HG (FelPro 1014) gives you 86cc, the piston in the hole needs to get you another 6.5cc. And it's not the best way by going that route, but doable.
     
  8. 1980RS

    1980RS Veteran Member

    Messages:
    4,865
    Likes Received:
    1,454
    Joined:
    Jun 17, 2006
    Location:
    MN
    Ya I guess running high 10's with mild Vortec heads is out of the question, remember bigger heads don't always make big performance.
     
  9. sandlapper

    sandlapper Veteran Member

    Messages:
    517
    Likes Received:
    168
    Joined:
    Oct 9, 2020
    Location:
    SE CSA
  10. G72Zed

    G72Zed Veteran Member

    Messages:
    2,376
    Likes Received:
    1,043
    Joined:
    Sep 8, 2015
    Location:
    Canada
    Just make sure there's no overhang with a 4.165 HG on a 4.155 bore, that's tight, and you can make your own steam holes.

    I hate "crevice volumes" stack up....be it low top ring placement or overly big bore HG for the application.
     

Share This Page