302 Power Loss When Accelerating Help

Discussion in 'Technical' started by PerformanceMav, May 23, 2019.

  1. PerformanceMav

    PerformanceMav Member

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    I own a 1973 Ford Maverick. I recently rebuilt the 302, the C4 transmission, and added hooker headers on it. I added a 600 cfm Holley street warrior, with a performer intake. Just about every part in the engine bay is brand new. My problem is when I floor it while in drive or reverse the engine will loose power and then turn off. The car feels extremely sluggish. I checked the timing and vacuum. I am completely confused on what the problem could be. The only thing that I haven't attached in the kick down cable. Is it that important? If not what could be other issues?
     
  2. 71gold

    71gold Frank Cooper Supporting Member

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    kick down should have no issue when taking off.
    did you put in a new converter when rebuilding the C-4?
     
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  3. PerformanceMav

    PerformanceMav Member

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    Yes we did. How likely would a new torque converter be defective?

    Thank you
     
  4. Hotrock

    Hotrock Rick, an MCCI Member Supporting Member

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    You have not provided us with a great deal of information. What is the history on the Holley carburetor? Is it new, used? Can you verify it's reliability?

    What about the ignition system? Original point system, or updated to electronic?
     
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  5. Krazy Comet

    Krazy Comet Tom

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    The only part(systems) that will cause total stall out are either ignition related, carburetor, lack of fuel, possibly collapsed fuel line, plugged tank strainer or weak pump. Forget linkage, torque converter etc.

    If main jets(or their circuit) in carb are plugged up engine will idle fine with good vacuum but totally fall on its face when throttle is opened. A/F ratio so lean engine will stall almost immediately. Approx same with weak spark, though usually there is some misfiring(studder) before stall.

    Two or three years ago someone chased their tail over poor performance, I believe went so far as to replace intake manifold. Problem turned out to be aftermarket ignition related.
     
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  6. RMiller

    RMiller My name is Rick

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    When was the last time the fuel filter was changed? I fell into that trap on a truck I put a new engine in, never crossed my mind to change it. It would drive fine at low speeds but when you leaned on it it would surge. One day on the way to work it just died. Thankfully I had used another fuel filter on the carb vent line to keep garbage out of the bowls so i just swapped them. Ran great from then on!
     
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  7. PerformanceMav

    PerformanceMav Member

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    The ignition system is brand new. We just changed the ignition system to a flame thrower pertronix system and installed Taylor wires today. It ran great but we are going to take it on the road tomorrow. The carb is new and should be reliable. I changed out the secondary spring to a white spring and it seemed to improve and not die out. I haven't had a ton of drive time with the new spring because my headers fried a wire. I will post an update tomorrow on how the drive goes and any other problems I might encounter.
     
  8. PerformanceMav

    PerformanceMav Member

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    Just changed out the ignition system we are going to see what kind of changes it makes tomorrow.
     
  9. PerformanceMav

    PerformanceMav Member

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    Thanks for your response. The fuel filter is brand new and is crystal clear. I still might replace it just in case there is some kind of defect but it seems to work perfectly.
     
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  10. PerformanceMav

    PerformanceMav Member

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    Ran the motor today. Same issues. Only a sputtering to a stall in gear once I get about half throttle plus. We reworked the wires to the coil to confirm that it was getting a solid connect and did a compression test which all the cylinders showed 150 with only one in the 130 range.
     
  11. Krazy Comet

    Krazy Comet Tom

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    Since ign didn't fix it, time to troubleshoot fuel system. A fuel pressure gauge will tell you if system up to carb is OK( 5.5-6.5 psi maintained). If that's OK, I'd substitute another carb.
     
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  12. greasemonkey

    greasemonkey Burnin corn

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    Have you tuned the carburetor at all? Set idle and mixture screws? What's base timing set at?
     
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  13. PerformanceMav

    PerformanceMav Member

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    The fuel pressure is great. Our next step is to replace the carb. I forgot a couple months ago I left the air filter off (also my hood is off the car) and we had a big storm. We got all the water out of the cylinders and changed the oil to make sure there was zero water, but it may have ruined the carb. It seems unlikely I would have a faulty carb right out of the box so it was probably the water. I'll change it and update the post so others who may experience this problem don't have to run in circle with their head cut off like me lol.
     
  14. PerformanceMav

    PerformanceMav Member

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    I tuned the carb both screws. I may have a damaged or faulty carb from water. I guess I will find out in a couple days when I replace it. The timing is set to 8 to 10 degrees in advance and seems to run beautifully when idling. It just seems under any kind of load it gives out and stalls. Around half way down it starts to die then if you floor it from there the engine seems to choke out then die, but if you slowly ease into it the engine will come close to stalling but pull through. Even when I get it to floor completely there is substantial power loss (worst than my 40 year old inline six). Also it can be worth mentioning that I don't have an exhaust on the car currently, only headers. We are going to slap an exhaust on it and see if it performs better.
     
  15. Hotrock

    Hotrock Rick, an MCCI Member Supporting Member

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    That rain water would have had little to no effect on your carburetor other than some entering the fuel bowl through the vent tube. Since your engine has run since then, any water in the fuel bowl would be long gone.

    An added exhaust system will have no effect on the issue you describe.

    Your next step should be to acquire a known quality carburetor (meaning it has been on a well performing engine in the resent past) and install that and observe how your engine performs. If your engine performs much better than it does now, your new out-out-of-the-box unit is the major culprit.
     
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