Any help selecting a torque converter

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Doc302

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I threw a rod in my 1973 mach1. It had a. 68 429 thunderjet, I planned to go back to 351c it is a q code car, but I ended up with a 528 stroker. It makes 580hp 620 ft lbs so needed to rebuild the c6 as well. Problem is I can not get a good answer on torque converter selection. Car is street driven weekend car shows and the like with an occasional 300mile run on the freeway. Not a daily driver. Occasionally take to strip but street radials no trans brake or anything exotic. 4:11 gears solid roller cam
254/260 at 0.50 lift .671/.678 lift single plane manifold. Cam sheet specifies 3500 stall converter power band is 3200-7200 rpm for the cam. The valve train is good for 7500 but realistically I would seldom rev above 6000. My engine builder says 3500 stall but transmission guy says he would stay around 2400 for street- arguing that 1 the brakes would not hold to 3500 and 2 the flash stall on most converters is based on small block making 350-400 hp. Not a big stroker so the converter will actually stall higher then rated. Also do I need an anti ballooning plate? Although I understand the physics of a torque converter it still seems there is a dash of voodoo to it and getting it wrong either direction can cause problems. Any advice would be appreciated.
 

JJU9507

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No nitrous, no ballon plate, contact circle d converters for best choices, they will want a detail;ed converter spec sheet filled out from their site.
 
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I would say that both your transmission guy and your engine builder are correct, they are just coming at it from different directions. You really need a "real" 3,500 stall converter for YOUR combination like your engine builder says. The transmission guy is also correct in stating that "published stall speeds" are based on your average 350-400HP small block, and that an advertised 2,400 stall may be enough, as your engine makes so much more power than average, that it will effectively have a much higher stall speed. The trans guy is also probably correct in that you will never see 3,500 with the brakes. The stall speed is based on the "flash" of the converter and not on what you will get when you foot brake it off the line. The issue with converters is that the stall speed of any converter is not fixed, there is really no such thing as a 3,500 stall converter. Manufacturers advertise them as such, so that you can have an idea of what you are buying, but when you buy a 3,500 stall converter the possibility of it actually flashing to exactly 3,500 are slim to none. Two things affect the stall speed you will see on your converter, the weight of the car, and how much power the engine makes. The heavier the car, the higher the stall speed, and the more power also the higher the stall speed. I really do not want to make this too long but you can have the exact same 400hp small block and the exact same converter on two different cars and the stall speed could be dramatically different. If you have that engine and converter on a 2,000 pound car you could end up with only a 2,500 stall, but if you put the same thing on a 4,000 pound car you could easily have a 3,500 stall speed. Works the same way around if you have the same weight car and converter, but one with 350 HP and one with 600hp... Being that you are so far from what the average is, your best bet is to contact your favorite converter manufacturer, tell the the HP/TQ of your engine, and the weight of your car and they will be able to get you exactly what you need. As the previous poster said, you do not need an anti-ballooning plate.
 

Doc302

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[url=https://ibb.co/dQW99z][img]https://preview.ibb.co/bEMnwe/Mach_1_front_side_up.jpg[/img][/url]
No nitrous, no ballon plate, contact circle d converters for best choices, they will want a detail;ed converter spec sheet filled out from their site.
Thank you- I’ll try circle d- filled spec sheet for TCI. and Hughes with no response but it has only been a week
 

Doc302

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1973 Mach1 Q code 351 replaced with 1968 “429 thunder jet”


[url=https://ibb.co/dQW99z][img]https://preview.ibb.co/bEMnwe/Mach_1_front_side_up.jpg[/img][/url]
I would say that both your transmission guy and your engine builder are correct, they are just coming at it from different directions. You really need a "real" 3,500 stall converter for YOUR combination like your engine builder says. The transmission guy is also correct in stating that "published stall speeds" are based on your average 350-400HP small block, and that an advertised 2,400 stall may be enough, as your engine makes so much more power than average, that it will effectively have a much higher stall speed. The trans guy is also probably correct in that you will never see 3,500 with the brakes. The stall speed is based on the "flash" of the converter and not on what you will get when you foot brake it off the line. The issue with converters is that the stall speed of any converter is not fixed, there is really no such thing as a 3,500 stall converter. Manufacturers advertise them as such, so that you can have an idea of what you are buying, but when you buy a 3,500 stall converter the possibility of it actually flashing to exactly 3,500 are slim to none. Two things affect the stall speed you will see on your converter, the weight of the car, and how much power the engine makes. The heavier the car, the higher the stall speed, and the more power also the higher the stall speed. I really do not want to make this too long but you can have the exact same 400hp small block and the exact same converter on two different cars and the stall speed could be dramatically different. If you have that engine and converter on a 2,000 pound car you could end up with only a 2,500 stall, but if you put the same thing on a 4,000 pound car you could easily have a 3,500 stall speed. Works the same way around if you have the same weight car and converter, but one with 350 HP and one with 600hp... Being that you are so far from what the average is, your best bet is to contact your favorite converter manufacturer, tell the the HP/TQ of your engine, and the weight of your car and they will be able to get you exactly what you need. As the previous poster said, you do not need an anti-ballooning plate.
Thank you for the explanation- very helpful
 

Hemikiller

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I run four speeds, but a good friend has used Ultimate Converter Concepts with great results. Lenny was the guy behind the converters from Dynamic Transmissions before forming UCC. He sold UCC to his employee a couple years ago. My buddy uses an Ultimate converter in his 540 powered 70 RoadRunner, and ran one of Lenny's Dynamic converters for twenty years before that. Not sure if Lenny is still there on a day to day basis, but they have an excellent reputation.

 
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All of the above is true, regarding converter operations. However, the rear end ratio also plays an important part in selecting a torque converter, especially for cars driven on the highway. There is a spreadsheet in this thread that will give you some more information and a selection calculator.
 
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I threw a rod in my 1973 mach1. It had a. 68 429 thunderjet, I planned to go back to 351c it is a q code car, but I ended up with a 528 stroker. It makes 580hp 620 ft lbs so needed to rebuild the c6 as well. Problem is I can not get a good answer on torque converter selection. Car is street driven weekend car shows and the like with an occasional 300mile run on the freeway. Not a daily driver. Occasionally take to strip but street radials no trans brake or anything exotic. 4:11 gears solid roller cam
254/260 at 0.50 lift .671/.678 lift single plane manifold. Cam sheet specifies 3500 stall converter power band is 3200-7200 rpm for the cam. The valve train is good for 7500 but realistically I would seldom rev above 6000. My engine builder says 3500 stall but transmission guy says he would stay around 2400 for street- arguing that 1 the brakes would not hold to 3500 and 2 the flash stall on most converters is based on small block making 350-400 hp. Not a big stroker so the converter will actually stall higher then rated. Also do I need an anti ballooning plate? Although I understand the physics of a torque converter it still seems there is a dash of voodoo to it and getting it wrong either direction can cause problems. Any advice would be appreciated.
Curious about your intake manifold selection for that camshaft and hood clearance? I have brand new B&M 40412 in unopened box, it’s advertised 2500 stall. $270 shipped
 
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