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Thread: New engine tune/edelbrock/bog
          
   
   

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  1. #1
    93F250 is offline CHR Member Visit my Photo Gallery
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    New engine tune/edelbrock/bog

     



    So i just got a new engine and trans going and so far its pretty good but im having trouble with the fine tuning. Th350 and 350 mild head work, cam 230/230 @50, rpm intake, msd hei, edelbrock 1406, 2000 stall(b&m holeshot).

    Over 3500k it hauls and putting around its ok but give it too much gas and get into the secondaries and it bogs or stumbles then starts to pick up.

    About 14.5vac at 850-900rpm

    Timing is 25 initial 35 total

    Adjusting the shot on the accelerator pump doesnt seem to make much difference, it sprays great though and starts as soon as you touch it.
    .95 secondaries .98 main jets .70 x .37 rods. Leaned out or like this the bog is still there but its better now that i richened it. Still wont spin the tires, ive had half dead 350s that would spin the tires..

    Any help is much appreciated

  2. #2
    techinspector1's Avatar
    techinspector1 is offline CHR Member Visit my Photo Gallery
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    Your half dead 350's probably didn't have a 230/230 cam killing the bottom end. Any cam that you put in the motor has a dedicated 3000 to 3500 rpm operating range, like 1000 to 4250 (that will spin the tires)......or 1500 to 4750...... or 2000 to 5250...... or 2500 to 5750......or 3000 to 6250......or 3250 to 6500......or whatever.

    Here's the verbage from Crane Cams concerning their 230/230 flat tappet hydraulic cam characteristics.......
    Performance usage, good mid and upper RPM HP, bracket
    racing; Street, Heavy, etc., auto trans w/3000+ converter,
    oval track; Street Stock, Enduro, Hobby, etc., 1/4-3/8 mile,
    serious off road, 10.0 to 11.5 compression ratio advised.

    3000+ means 3500. And I doubt seriously that your motor has between 10.0 and 11.5:1 static compression ratio. Do you know the static compression ratio? Do you know the squish/quench?

    The camshaft is not a stand-alone part. It must be coordinated with all the other parts of the car, such as static compression ratio, intake manifold design, carb size, weight of the car or truck, torque converter stall, number of gears in the transmission and their ratios...... and differential gear ratio.

    Your 230 cam needs (ideally) 10.75:1 static compression ratio, 3500 stall converter (to get the motor up past the dead zone) and some rear gears up into the 4's. Problem with such a static compression ratio is that with iron heads, the motor will be prone to detonation on pump gas. The generally agreed upon limit for iron heads on pump gas is about 9.5:1. For static compression ratios above that, aluminum heads would be highly recommended.

    Bottom line: You have over-cammed the motor.
    .
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  3. #3
    DennyW's Avatar
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    ........................All Done...
    Last edited by DennyW; 09-10-2017 at 11:27 AM.
    Rrumbler likes this.



  4. #4
    rspears's Avatar
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    Quote Originally Posted by 93F250
    Over 3500k it hauls and putting around its ok but give it too much gas and get into the secondaries and it bogs or stumbles then starts to pick up.
    Quote Originally Posted by techinspector1 View Post
    3000+ means 3500. And I doubt seriously that your motor has between 10.0 and 11.5:1 static compression ratio. Do you know the static compression ratio? Do you know the squish/quench?

    Bottom line: You have over-cammed the motor.
    Tech's spelled it out clearly, and your post actually says that the engine is doing pretty much what it should be doing, but would likely be stronger if your compression ratio was boosted and you were running aluminum heads and high octane gas to handle detonation. Seems like you've got some changes in your future, but you need to know your base before you start throwing more $$$ into the pit. Assuming your screen name (93F250) is the vehicle in question, dropping a SBC into a Ford truck is where your problems started..... (just kidding, just kidding).
    Roger
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  5. #5
    93F250 is offline CHR Member Visit my Photo Gallery
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    Quote Originally Posted by techinspector1 View Post
    Your half dead 350's probably didn't have a 230/230 cam killing the bottom end. Any cam that you put in the motor has a dedicated 3000 to 3500 rpm operating range, like 1000 to 4250 (that will spin the tires)......or 1500 to 4750...... or 2000 to 5250...... or 2500 to 5750......or 3000 to 6250......or 3250 to 6500......or whatever.

    Here's the verbage from Crane Cams concerning their 230/230 flat tappet hydraulic cam characteristics.......
    Performance usage, good mid and upper RPM HP, bracket
    racing; Street, Heavy, etc., auto trans w/3000+ converter,
    oval track; Street Stock, Enduro, Hobby, etc., 1/4-3/8 mile,
    serious off road, 10.0 to 11.5 compression ratio advised.

    3000+ means 3500. And I doubt seriously that your motor has between 10.0 and 11.5:1 static compression ratio. Do you know the static compression ratio? Do you know the squish/quench?

    The camshaft is not a stand-alone part. It must be coordinated with all the other parts of the car, such as static compression ratio, intake manifold design, carb size, weight of the car or truck, torque converter stall, number of gears in the transmission and their ratios...... and differential gear ratio.

    Your 230 cam needs (ideally) 10.75:1 static compression ratio, 3500 stall converter (to get the motor up past the dead zone) and some rear gears up into the 4's. Problem with such a static compression ratio is that with iron heads, the motor will be prone to detonation on pump gas. The generally agreed upon limit for iron heads on pump gas is about 9.5:1. For static compression ratios above that, aluminum heads would be highly recommended.

    Bottom line: You have over-cammed the motor.
    .
    Unfortunately i didnt build the package i just got a good deal on it. Its a lunati cam and they recommend a 2500 stall, the b&m is supposed to be 2400 but its more like 2 and it will flash to 2200 sometimes. Would that reslly cause the bog? Should i jumo to a 3500 then? This b&m is junk anyways in my opinion.

    I was told the compression was brought up from stock but not by alot.

    One of my next purchases will be alumunim heads from blueprint but for the time being i need to get this combo running best i can.

    Ive driven rigs with a 350 and similar set ups (too big a cam for the heads). Im almost positive i have it tuned wrong or the secondaries are opening too soon. Its not where it could be with the set up it has now. Heads and torque converter are next though

  6. #6
    93F250 is offline CHR Member Visit my Photo Gallery
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    To be completely clear it does not matter what rpm it is in if the truck is floored it bogs. If its been floored for a sec let up for a couple sec then floor it, it will bog.

  7. #7
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    Quote Originally Posted by rspears View Post
    Tech's spelled it out clearly, and your post actually says that the engine is doing pretty much what it should be doing, but would likely be stronger if your compression ratio was boosted and you were running aluminum heads and high octane gas to handle detonation. Seems like you've got some changes in your future, but you need to know your base before you start throwing more $$$ into the pit. Assuming your screen name (93F250) is the vehicle in question, dropping a SBC into a Ford truck is where your problems started..... (just kidding, just kidding).
    Ahaha i get that a lot. Screen name is my first truck and my screen name on every forum ever. Still have it and it def wont be getting a chevy engine lol.

    This set up is actually in an 84 k10 but the hot rod and car sites have better engine tech

  8. #8
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    Check your accelerator pump. Being over cammed, you probably need to set the accel pump for max volume.

    Or, stop stomping it.
    .
    Education is expensive. Keep that in mind, and you'll never be terribly upset when a project goes awry.
    EG

  9. #9
    jerry clayton's Avatar
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    Edelbrock secondaries opening too fast/soon--------problem often shows up when a person is using carbs with small primaries and huge seconaries-I don't know about Edelbrock if it has the extra baffles like a Quadrejet------but I would never, ever try to run a carb like that-I'd prefer a big primary and a smaller seconary-

  10. #10
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    This is why I have refused to buy a complete motor all my life, because nobody builds them to suit me. I have always bought rebuilder cores and parts and engineered the whole mess myself. In that vein, I would advise that you disassemble this motor, find out what's in it and re-engineer the build so that it suits your needs.

    "Unfortunately i didnt build the package i just got a good deal on it."
    Still think it was a good deal ???
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  11. #11
    93F250 is offline CHR Member Visit my Photo Gallery
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    I dialed in the springs this morning and played with it some more, even in park as soon as the linkage hits the secondaries it bogs then picks up a second later

  12. #12
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    I believe an Edelbrock 1406 carburetor is a copy of a Carter AFB. It is a square bore carburetor. Unfortunately the secondary's are not readily adjustable on that type of carb. Ideally, when you stomp on the loud pedal, the secondary's should smoothly open over about 1 1/2 to 2 seconds. You can basically do the same thing with your right foot. Smoothly push the gas pedal down over about 2 seconds and see if that "fixes" the bog.

    Also, like Tech said, it's not going to be a strong runner off idle with that big cam in it.
    Steve

  13. #13
    93F250 is offline CHR Member Visit my Photo Gallery
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    Got a vac can that worked and Re did the timing curve. 16 initial. Running a lot better, still bogs(rpms drop) when the secondaries open. Does not do it in park anymore.

    Easing into it like you said helps a lot but there is still an rpm drop

    Takes off better now when it catches up tho. I get that it might not be the best performer off the line but the rpm drop when the secondaries open is a carb/tuning issue right?
    Im just trying to get the best out of what i have at the moment until i can add the things it needs, i feel like i should be able to remove this rpm drop with tuning. Am i just dead wrong?

  14. #14
    Driver50x's Avatar
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    Most carbs have adjustable secondaries, but I'm not sure how to do it on that particular carburetor.
    Steve

  15. #15
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    Secondary air valve, screw adjustment on the drivers side air horn. Could help it.
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