Max lift stock 452 + cam for smog '77 400

Engine, Transmission & Driveline

  1. Metalmarty

    Metalmarty Member

    Messages:
    94
    Likes Received:
    47
    Joined:
    Feb 24, 2020
    Location:
    The Netherlands
    Hi All,

    I've got some basic questions I can't really find the answers to.
    Not a lot of people use the 400 engines, and almost every post I can find about this engine is people saying "up the compression". I agree, the late 400 engines have shitty low compression. But it's what I have and I don't have the money to play with higher compression ratios. And these engines can still be a lot of fun.

    And remember, I'm from the country where people drive 60ci cars with not a lot of horsepower. :lol:

    To answer the first to be asked questions:
    I've send multiple Cam manufacturers a message, but I want to hear some experiences.
    This is a cheap/budget build.
    No I'm not taking the heads off to up the compression.
    No I'm not replacing the heads. :)

    I've got a '77 Chrysler 400 engine for in my '68 Newport.
    (original 383 too expensive to fix at the moment).
    I'm thinking of swapping the camshaft before the engine goes in.
    Not looking for a lot of power, just for a bit more than stock.
    I'm just not sure if it's worth it with this engine.

    Thumpr/Whiplash cams are always advised for low compression engines, but I don't think I can get away with one. I have power brakes and I'm planning to keep them!

    Some specs:
    - stock 1977 400 engine
    - 135-150PSI on all holes
    - edelbrock DP4B intake with rebuild edelbrock 1406 600CFM carb
    - New electronic ignition system (distributor, coil, leads, box etc)
    - Hedman 78070 short headers
    - Dual 2.5" exhaust
    - 2300-2400RPM stall converter
    - 3.23 rear gear
    - Power brakes

    Is it at all worth it to swap out the stock cam in this engine?

    It has 452 heads on it. What is the max lift (on average) on these heads?
    Can you always get away with .480-.500 lift or it that already cutting it close?

    Sorry for another cam thread. I'm really looking for experiences. :)
     
  2. 413

    413 Well-Known Member

    Messages:
    733
    Likes Received:
    235
    Joined:
    Jan 28, 2019
    Location:
    NW USA
    Just drive it like it is. Leave the cam alone, or use the cam from your 1968 383.
     
    • Agree Agree x 1
  3. Metalmarty

    Metalmarty Member

    Messages:
    94
    Likes Received:
    47
    Joined:
    Feb 24, 2020
    Location:
    The Netherlands
    Thanks for your thoughts. The 383 is not usable anymore unfortunately. So that's out.
     
  4. CBODY67

    CBODY67 Old Man with a Hat

    Messages:
    5,598
    Likes Received:
    1280
    Joined:
    Mar 27, 2011
    If you look at available camshafts, almost everything with the .475"+ lifts also have very long durations and long overlaps, too. Not good for anything like a low compression engine. So that limits your choices immediately. To keep enough idle vacuum for power brakes, it'll probably need a 114 degree "centerline" (which is close to the stock cam's number).

    Aim for "asymetrical lobe configuration" cams, which open the valve quicker and close them slower, and usually have "more area under the lift curve" than normal-lobe cams do. End result, more airflow into the cylinder without the higher lifts and/or longer durations. Comp Cams started them in the later '70s and Lunati has some grinds like that now. Lunati has a "factory performance" cam which replaces the 440/375 (also 383/335) cam, which one member has in a '68 383 4bbl, stock heads and pistons, that he claims works very well. But his factory motor is rated at 10.0CR. Check that one out. DO upgrade to a roller timing chain, for long-term "insurance" in that area.

    The easiest way to increase the compression ratio, without new pistons, on the 8.2CR moitors is to put the earlier,, pre-906 casting heads on the motor. Smaller chambers than the 906 and later 452. Simple bolt-on, same gaskets for the intake and such.

    Enjoy!
    CBODY67
     
    Last edited: Nov 13, 2020
    • Like Like x 1
    • Agree Agree x 1