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Technical stock c4 converter vs 3,000 RPM stall converter

Discussion in 'The Hokey Ass Message Board' started by birdman1, Sep 7, 2019.

  1. birdman1
    Joined: Dec 6, 2012
    Posts: 995


    Okay, i have a 351 cleveland ,2v, in my 1955 t-bird. I am using a c4 with stock converter. All I had for a cam was a 240*, .550" lift hydraulic cam. I am also using a 360* aluminum high rise intake manifold, headers, and electronic ignition. It won't idle below about(no tach) 1000 RPM. so it wants to die when transmission is engaged. I played with the timing, vacuum advance, a new 750 holley 4160. getting disgusted at all the problems. what I need to know is if a high-stall converter will allow the engine to idle at a lots higher RPM? I know the actual stall RPM goes up, but what about the idle?? thaks,Hnery
  2. F-ONE
    Joined: Mar 27, 2008
    Posts: 2,273

    from Alabama

    There's more to it like the overall combo of engine, transmission, gear ratio and what the final goal is.

    It sounds like you have a “ barnyard mix” of parts. Racing engine parts + stock or mild drivetrain parts.

    Stalling the C4 will help but if the car needs a lower gear to function matched to the engine rpm, the transmission could fail due to overheating.

    You don’t want stall speed higher than final drive speed. This causes the transmission to slip all the time. This goes back to gear ratio.

    It may be more prudent and less trouble to run a less radical cam.

    Yes a stall will let it idle in drive. It does nothing in park or neutral.
  3. Install a manual trans, problem solved....
  4. southcross2631
    Joined: Jan 20, 2013
    Posts: 4,022


    Depends on who is building the convertor. I ran a tight 3200 stall in my old pro street Morris Minor with an AOD and a .512 lift hyd. roller in my 5.0 for 3 years as a daily driver. Just run a little lower gear in the rear and slippage is not an issue. Run a good trans cooler.
    Don't buy a cheap convertor . Let me recommend Allen Pope racing transmission's build you a convertor.

  5. LM14
    Joined: Dec 18, 2009
    Posts: 1,934

    from Iowa

    I put an E-303 roller cam in my '32s 5.0 engine backed by a C4. It (the cam) advised using a slightly raised stall speed. I went with a Hughes "street rod" converter. It's supposed to be 4-600 higher than stock but not radical enough to slip at cruising speeds. Just started the engine the first time the other day and it does let it idle without trying to creep or choking down.
  6. lostone
    Joined: Oct 13, 2013
    Posts: 1,374

    from kansas

    If it's wanting to idle around 1000 rpm I'd run a 2200 stall. That should get you the ability to idle in gear, actually stop at a corner instead of the motor trying to push you thru the intersection and that lower stall shouldn't cause you too much trouble with the trans, just run a good trans cooler.

    And yes, you start running bigger cams, intakes etc your going to need to run stall converters to compensate for the changes in idle rpms.
  7. David Chandler
    Joined: Jan 27, 2007
    Posts: 1,101

    David Chandler

    Remember stall speed is based on load and incoming torque. It may not stall at 3 grand, if the load is light enough, and you are not dumping lots of torque into it. Do run an augmented cooling system to shed excess heat. I ran a slightly increased stall speed unit in a pickup with no problem. If I had to do it again, I'd go up to the next rated unit. simply to get more bottom end.

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