1. Terry Hauck

    Terry Hauck Choadicus

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    What is the max lift and duration cam that can be installed in a base 383 Roadrunner engine?
     
    Last edited: Dec 8, 2017
  2. ykf7b0

    ykf7b0 Well-Known Member

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    I would keep it under .500 lift and duration under .235 @ .050. These numbers worked for me with a stock 440.
     
  3. 69hemibeep

    69hemibeep Sponge Bob Square Wheels

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    I have read 484 to be safe in an early stock engine if you float a 509 the valves will hit. Take into consideration the duration and have fat head gaskets been installed. The later smog engine will take more lift but don't have the compression to make a big stick work. Its real easy to over cam a motor.
     
  4. quikbird

    quikbird Well-Known Member

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    think about and define the purpose of your engine and then call comp or somebody and see what they recommend. cam, lifters, pushrods, and rocker ratio all play a factor in your choice.
     
  5. Russ69Runner

    Russ69Runner Well-Known Member

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    Haven't been their in a while but wile fishing around for 383 speck's found a page that showed stock speck's. But showed other ratios for the motor depending on what you want to do. I searched 383 Plymouth big block and stumbled on to it. Good luck Terry. :D
     
  6. Terry Hauck

    Terry Hauck Choadicus

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    Thanks for the info. A buddy that has a ton of 440 parts he has tried over the years gave me a cam that is a bit bigger than a stock 440 Magnum one, in the 480 range he says. Also have an Edelbrock RPM Performer and a 750 carb and a windage tray to install. My Christmas break project. Will advise how it works out.
     
    Last edited: Dec 15, 2017
  7. Terry Hauck

    Terry Hauck Choadicus

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    I decided to go with a Comp 145-1224. Its a 488/491. Under 500 so I should be OK.
     
  8. Coyote

    Coyote Well-Known Member

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    Should work. Did you go with adjustable valvetrain?:beep:
     
  9. Terry Hauck

    Terry Hauck Choadicus

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    No. Stock 906 heads setup. New lifters and springs.
     
  10. Coyote

    Coyote Well-Known Member

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    Should have decent performance and the idle ought to impress the cruise in crowd.:steering::beep:
     
  11. CompSyn

    CompSyn Well-Known Member

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    A lot of factors go into this, block decked, thicker head gaskets, heads milled, actual deck height, etc. That said, a friend of mine installed a Mopar .509 Purple Shaft into a stock 68 383 HP engine. He would beat the living daylights out of this engine. Heads had factory Magnum valve springs. At the strip, he would float the valves regularly. Don't know that he ever had issues with interference but it was a solid performer as long as he owned it.

    This is why I question the use of pistons with deep compression robbing valve reliefs for milder street/strip 383s.
     
  12. Terry Hauck

    Terry Hauck Choadicus

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    I have the .039 felpro gaskets and I will be having the stock 906 heads worked adding new 440 source Stealth head springs with Comp keepers and retainers. Not sure
    what type piston this is but they do not extend above the deck.



    Piston.jpg
     
  13. quikbird

    quikbird Well-Known Member

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    Anything with a dish in it lowers your compression ratio. Normal piston is a flat top I think
     
  14. Terry Hauck

    Terry Hauck Choadicus

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    I think this is a base 383 block with the HP parts bolted on. One day I will rebuild the whole engine.
     
  15. Coyote

    Coyote Well-Known Member

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    A suggestion: Unless you have an “in” at your local machine shoppe, IMHO you would be $ ahead to do a crate motor.

    Everybody should build one, but the money involved in machine work will eat you alive. I’ll bet it would be way(!) over your anticipated budget

    An option I like is get an assembled short block. You can then pick your own cam, cylinder heads, valvetrain, and ancillary stuff.

    I believeyou’d be money and time ahead.:soapbox::steering::beep:
     
  16. RKNRLR

    RKNRLR Well-Known Member

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    have to agree after having mine done from the ground up recently. Machining the block was probably the longest part of the process, wouldnt trust my block with just anyone, and anyone worth their weight in salt wont have much free time.
    Unless you can find a crate long block your 100% happy with, an assembled short block is a good starting block for you to pick and choose your top end.
     
  17. 69hemibeep

    69hemibeep Sponge Bob Square Wheels

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    I must be lucky to have a good reasonable shop near me, I enjoy building them.
     
  18. quikbird

    quikbird Well-Known Member

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    Just ask coyote how many times he's rebuilt the last one
     
  19. Coyote

    Coyote Well-Known Member

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    We have a great machine shoppe! The prices are astronomical, definitely value received. Still a ton of money.

    I picked the wrong shop at first. Oops!
    Getting it squared away was time (lots) and money lots also.

    To soon olde/too late smart!:beep:
     
  20. ACME A12

    ACME A12 Plaid Sport Coat Wearing Moderator Staff Member

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    Me too. Best part of any build. Been best buddies with my machinist since 1981. If you see me buy a crate motor you'll know that an "Invasion of the Body Snatchers" type of event has taken place. :D
     

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