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Thread: 460 Head Upgrade

  1. #1
    What improvement could i expect by installing a fresh set of cj heads on my stock 88 460 king cobra. Its rated at 340hp now. Thanks

  2. #2
    spectras only
    I would change the camshaft to fomoco part A 443 .Check the size of your carb,min 750 CFM to 850 would suffice.Make sure you get the 7/16 rocker arm studs with the 7/16 guide plates and hardened pushrods .Rocker arms [1.7 ratio] would be your choice , roller tips or full roller .Also get dual springs if you have single springs with damper springs only.Seat pressure should be min 130 pounds to 300 open ,to control valve'll have over 400+HP.

  3. #3
    Spectras Only, Thanks for the reply,I only have 300 hrs on the stock motor and i really don't at this time want to pull it out.The carb is a 750,it would be nice to put these heads on for now and leave it at that till the time comes to do something a little different.Where do you think with this change i will end up. Thanks
    ps. i can get these heads for hardly jack.

  4. #4
    spectras only
    Just changing heads ,wild guess is you'll go from 340 to 365/375 HP.The King Cobra heads you got right now has 9:1 comp ratio ,so I guess going to the CJ heads your comp ratio will be bumped around 10:1 . Someone might have a different figure ,so let them chime in wink
    [ September 18, 2002, 08:32 PM: Message edited by: spectras only ]

  5. #5
    When you install those CJ heads make sure you check the piston to valve clearance as the CJ valves are much bigger than the piston reliefs for use with stock size valves. eek!

  6. #6
    058, Oh shit,I thought that this was going to be easy. You say I need to do the puddy test? What kind of clearance am i looking for . Thanks

  7. #7
    YES!!! Check with clay, Play-doh, Silly Putty, window sash...anything. What you are looking for is to check the bigger valve will fit in the piston relief, some do and some don't depending on the piston. All the reliefs are deep enough just not big enough, that is if you are running a mild cam. [They won't be deep enough if you are trying to run a .700" lift cam]

  8. #8
    spectras only
    058 is right ,if you're going to change cam for high lift later[I thought waterrocket wants to replace the heads only,since he's hours are low on his engine?].The A443 cam has around 560 lift on both valves and will clear with late model 460 deck heights.

  9. #9
    Now its starting to sound a little better. What ratio roller rockers should i run with the stock cam. And do i really need to install stainless valves. Thanks

  10. #10
    Oh, i forgot as posted above 1.7 ratio, is that what i have now?

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