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Thread: torque converter street/strip

  1. #11
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    Yes, but no, that looks like the OEM Convertor from my first 74 Z28 that was destroyed in August of 80. They used 6 mounting points with 3/8 bolts and were rated at 2400 stall. A Z28 was the only Camaro equipped with a TH400 in 74 as they were considered special high perf. I have also seen the 6 lug convertor in 1 ton trucks, no idea on their specs.
    Last edited by markm; 08-23-2018 at 07:05 AM.

  2. #12
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    My two cents Tony, if the car is driven mostly on the street, the 3000 rpm stall is too high for me. The converter is too loose and the rpm has to change so much just to make small changes in speed, so the motor seemed to go from idle to 2500 or so continuously.

    Another comment on the vibration, I had a problem and it turned out to be the engine damper, even though it was a new TCI with no visible signs of a failure. I changed it out and the vibration went away.

  3. #13
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    Yes I didn't think of measuring it. It's almost 13", my current one is about 11.5". That would have been slick if it was 10" I would have given it a try.
    Tony

    1955 Bel Air Sport Coupe

  4. #14
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    Thanks for the input Richard. I had changed the harmonic balancer a while ago with no change. My current TCI is rated at 2400
    Tony

    1955 Bel Air Sport Coupe

  5. #15
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    That’s the same value we swapped in. The motor was a carb’ed 383, hydraulic roller, aluminum heads with a 200R4 trans (w/lockup converter on a toggle switch) and 3.23 gears. It worked well.
    Last edited by TrifiveRichard; 08-23-2018 at 12:56 PM.

  6. #16
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    Hmm, so maybe if this converter isn't causing the vibration, I should leave well enough alone? And your locking converter, I have often thought of using a simple toggle switch just for on the highway. Was it a full manual valve body too? If I did that I'd add just a little bit of electronics with a relay that unlocked it at low speeds and/or really simple a relay activated by the brake lights that cut off the lock up.

  7. #17
    Registered Member chasracer's Avatar
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    I have to go with the general consensus here. When it comes to converters it's best to deal directly with a manufacturer, give them all the information you can about your engine, your chassis setup and how you are using the vehicle. Most of them can steer you in the right direction which in your case is probably going to be a 10" street unit that with your BBC should be able to hit 3400-3600. I am not sure I follow the vibration information but connecting the converter might be okay but now sure it proves anything. I would install a new flexplate at the same time, preferably an SFI one, you will need new bolts for the converter and make sure you measure everything properly to get the new converter installed correctly. If you have any questions on that I have a little write-up on my website that may help you out, just let me know.
    Remember the "13"


  8. #18
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    3400 to 3600 sounds pretty high when the cam only calls for 2500+ (doesn't say plus how much)? As far as the vibration, since it doesn't vibrate now, and I add the converter - then it vibrates, that would tell me my converter is off balance. But damn, unless I raise the car high enough that I can sit up under it, I don't think I can hold the converter itself up while I struggle to get a bolt in, then turn it. I have an SFI flex plate coming, and a flex plate engine turning tool also. It would have been here today but ups says they mis-sorted my package.
    Sure, shoot me a link to your web page and I'll give it a read.

  9. #19
    Registered Member chasracer's Avatar
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    Well, there's a difference between "stall or flash rpm" and operational rpm for a converter. I mean we drive around the pits with 8" units that will flash anywhere between 5800 and 6200 and it's no different than leaving a stop light and going down the street. But, if we hammer it that's when you see the difference. So while a flash of 3400-3600 might seem a bit high under normal usage a street style 10" unit is pretty livable. Yes, there's a bit more heat involved but you would be running a trans cooler anyway so that's not even an issue. Typically what we see in ads as far as stall RPM, the number is usually based on a reasonable small block motor combination - a BBC deal simply has more torque at the outset so the numbers are going to be a bit higher. Case in point, we have a Hughes unit in the Corvette roadster that we are trying out. Hughes told us that converter should flash somewhere in the 5100-5200 area but the 421 inch small block we have in the car is pretty healthy with just shy of 700 hp on tap so this converter is actually flashing at 5800 right now. If I put it behind my 555 BBC engine, it would probably go a touch higher. I am sending you the website link in a PM.
    Remember the "13"


  10. #20
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    chasracer is not agreeing with the "consensus" I'm reading because there isn't one.

    He is advocating a 3400-3600 stall.

    Trifiverichard is advocating 2400 stall.

    My advice was that increasing the stall from 2400 to 3000 increases the heat and slippage, and decreases the fuel mileage while increasing the performance (but only if you don't spin the tires, because you're going to be closer to doing that).

    So it's up to you to decide and find out what the real tradeoffs are between a driver and a race car. There is no pat answer.
    Last edited by Rick_L; 08-23-2018 at 06:39 PM.

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