School me again... first time tuning a BB

Big Block A body Tech

  1. Red_Duster

    Red_Duster Well-Known Member

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    Hi all! Finally really got to run my 440 Duster project around and while I was really excited to have it out on the road, I was running into some issues at 3/4 to Wide Open throttle. This is my first time tuning a BB Mopar or seriously getting into any engine.

    1970 440HP
    Edelbrock Performer RPM with 750 carb.
    906 heads with Crane adjustable rockers.
    Schumacher Headers
    Older Mopar 296 purple shaft.
    440Source ready to run Dizzy.

    Initial timing is at 18 BTDC and 34 Total. I capped off the Vaccum advance for now until I figure out what I’m doing. Idle in park is around 950 and gear is 700. It really doesn’t want to idle lower than that.

    Any thoughts on why I would be pinging at wide open throttle? To lean? To much advance? I’m at very new to this so it might be something really obvious I’m missing.
     
  2. RustyRatRod

    RustyRatRod 30 Degrees Outta Whack FABO Gold Member

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    Probably too much advance. If you can run a compression test and post the numbers we'll have a lot more info to go on.
     
  3. Red_Duster

    Red_Duster Well-Known Member

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    Just the man I was hoping would chime in. I don’t have a compression tester (still building up the toolbox) but I may be able to borrow one. I started at the 18 based one what I’d read and only having access to 91 octane. What should I be looking for if retard it and I went too far back?
     
  4. RustyRatRod

    RustyRatRod 30 Degrees Outta Whack FABO Gold Member

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    It may be coming in too soon, too. What RPM are you seeing 34 degrees total?
     
  5. pishta

    pishta I know I'm right....

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    I've seen 38 (all in at 1800) on a 440 but your camshaft has alot to do with this. Ask A/J..
     
  6. Red_Duster

    Red_Duster Well-Known Member

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    I’ll have to get a helper over to watch my tach. I just brought it up at the carb until the timing stopped advancing, but it was definitely over 1800, sounded closer to 2,500 but I will have to verify that.
     
  7. RustyRatRod

    RustyRatRod 30 Degrees Outta Whack FABO Gold Member

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    That's pretty early. What gear are you running?
     
  8. Red_Duster

    Red_Duster Well-Known Member

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    3.55 gears
     
  9. AndyF

    AndyF Well-Known Member

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    cast iron, open chamber heads are going to be a problem. you'll just have to tune around them. run premium fuel and back off the timing until it doesn't ping. the retarded timing makes them run poorly with a performance cam which is why many people get rid of the cast iron heads.
     
  10. Red_Duster

    Red_Duster Well-Known Member

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    Will do. I’d like to get the Edelbrock when budget allows. What would be a good starting point with timing? I should note that it’s only having an issue under load. In the garage it revs just fine. Not sure if that relevant or just normal. Like I said... newbie...
     
  11. famous bob

    famous bob mopar misfit FABO Gold Member

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    When the budget allows, I`d go trickflow over edelbrock any day !!
     
  12. Jim Lusk

    Jim Lusk Well-Known Member

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    Where are you located? There are two different Edelbrock 750s as well. You want the 1411, not the 1407.
     
  13. Red_Duster

    Red_Duster Well-Known Member

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    I’m in the Sacramento CA area. I believe the carb is the 1407. It was in the performer RPM package with the intake from summit back in the day.
     
  14. Jim Lusk

    Jim Lusk Well-Known Member

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    I may also be mistaken about the numbers as well. Did yours come with or without the electric choke? I get up that way from time to time, but there are others closer.
     
  15. cojohnso

    cojohnso Well-Known Member

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    Welcome to the jungle. Most BB with some build mods like higher initial timing for idle. But pay with some upper RPM popping? Not just a Mopar BB deal. Are you running a MSD? There are plug in modules that can retard timing at higher RPM. (Not a lot. It's not a variable timing setup. But can help.)

    A better cam grind for your setup is probably the best solution. I gave my setup to Comp cams. Their recommendation was a custom grind to replace my purple mopar grind. Slightly less lift with a little more diration. And it was noticeable. But can still have the balance fight under certain weather conditions. So I can safely say. Your situation is by no means unique.
     
  16. famous bob

    famous bob mopar misfit FABO Gold Member

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    Have the valve springs been checked/ Could it be floating a valve /weak spring ?
     
  17. cojohnso

    cojohnso Well-Known Member

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    In my case new springs. (from a different set back. Lol) But good point. It's one of the top questions from the cam companies.
     
  18. RustyRatRod

    RustyRatRod 30 Degrees Outta Whack FABO Gold Member

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    Have you run a compression test yet? It may be simple as a bad valve adjustment.
     
  19. Red_Duster

    Red_Duster Well-Known Member

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    Hey everyone. Thanks for all the feedback @RRR, I’ll have a everything to run a compression test tomorrow. I don’t think I’m floating a valve but it’s possible I set the lash incorrectly (first time doing that too). Wasn’t aware they could be related.
     
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    • Red_Duster

      Red_Duster Well-Known Member

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      Mine does have the electric choke.
       
    • AJ/FormS

      AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s FABO Gold Member

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      That's a 250 rpm drop going into gear, and is pointing to;
      A) That 296* cam,which, IIRC, is a P4120661; 252/252/110@.050/ @28/32 lash, .557/.557 lift@1.5 arms. That's big enough to kill the idle-rpm power quite significantly if the Static Compression was not raised in compensation, and/or
      B) a factory low-stall TC, and/or
      C) and a throttle that is too far closed.
      The engine just doesn't have the torque at low-rpm that it needs. This is why the compression test is so important. If you only have 120 psi, there is no cure for what ails this combo until you get the pressure up. But by 150 psi, you can look to other areas for a cure. But if your pressure is over 165psi, you are in big trouble.
       
    • george joseph reid

      george joseph reid Well-Known Member

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      Put a bottle of Lucas octane booster in and see if it helps. Seems to work on my junk and is only $7.99 here.
       
    • 1969383S

      1969383S FABO Gold Member FABO Gold Member

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      383HP with 3.55.

      18 or so initial limited to 34 @ 1800. Good starting and good cooling. Jumps right up with stock A manifolds and 800 AVS on TM-6. No ping and REC90 fuel. 292/509 cam. How much real compression? And what converter or stick?
       
    • Red_Duster

      Red_Duster Well-Known Member

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      Hey guys. Thanks for all the input and sorry for being away from the thread for a bit. I ran a compression test and was in the mid to high 140s across the board. in regards to the stall, previous owner stated it was 3k, but on my drive its only stalling to about 2k. I'm not sure the process to definitively test that but Ill look it up. When I ran compression I noted most of my plugs are pretty dark. I put in fresh plugs when I first fired it and went one step hotter than stock based on recommendation. Research says I should have went one step cooler? I picked up vacuum gauge to try and dial in my idle a little bit more and see if that helps?

      My plan at this point was to really dial in the idle based on vacuum, put fresh plugs one step cooler and see where I am at? I know I need a higher stall, but Ill have to hold off on that a month or two.
      Another silly first time RB A-body question, for those of you with TTI or Schumachers, getting to some of the plugs is awful. Ive read that people shoot access holes though the in fender. Does anyone have a picture of theirs? Worth doing?
       
    • Oldiron440

      Oldiron440 Well-Known Member

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      I've got that cam in a 9.5 440, timing is set at 16 at idle, 750 rpm, and 39 degrees total. This is with 452 heads that have been pocket ported with 2.14/1.81 valves. The combination made 520 hp 545 tq on pump gas with a old M1 single plane and Holley 850.
      It sounds like you don't have enough curve in the distributor, I would like to see a 22° sweep with a total of 38 or 39° all in by 2500 rpm at the latest.

      I am going to ask at what rpm the converter flash at and what does it stall at?

      I whould replace carb with a Holley style race carb with 4 corner adjustment to help with the idle.
      I would replace the carb before you replace the torqconverter.
      Because I suspect you are giving away lower end power with the carb and timing. Once you get it optimized then you can decide if you need to change the converter. I just looked and my 440 made 500 foot pounds of torque at 3500 rpm so it's got some lower end grunt. I'll go back to the dyno and see if we made pulls from 2500.
       
      Last edited: Aug 9, 2019
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