torque converters
- Thread starter Buster
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Screaming Metal
Active Member
A TC is a piece thats a double edged sword. The torque converter is made for a heavier car, to get your rpms up into a usable range to launch a big massive car at the lights on the dragstrip. They were in diff. dia.'s, and in diff. stall speeds.
You could use some stall in a light car, but, it makes them jerky and unsettling slipping away from a light. If you have a high winding motor in one of these little cars, with little low end torque, it'll help get you away from the light clean. If you got a torque monster sitting up front, you'll be breaking stuff and stressing stuff out.
As one who has seen more TCs in my career than I care to even try to guess at, I myself wouldn't go above 2000-2500 rpm. You should be able to flash stall your regular converter at 1800 or so if a smallblock. It depends on the torque of your motor also.
SINCE your not coming off the line in a 3300lb camaro at 3800 rpm with slicks and a 4 link.....I'd say tun a stock converter. Converters also make alot of heat with the slippage, and with a 383, you have a good bit of torque, with the 3.56. If things are anywhere near right, you should fry the skins out back easily.
In my opinion, and this is just my 2 cents, as light as these cars are, you really don't need a converter. A warmed up HP 350 with a stock Tc going thru a turbo 350 into a 3.56 rear.....it'd be hell on the street. You couldn't hardly get that thing to hook up! Unless you had slicks and some moose juice.........
Well, unless your Ted Brown!
You could use some stall in a light car, but, it makes them jerky and unsettling slipping away from a light. If you have a high winding motor in one of these little cars, with little low end torque, it'll help get you away from the light clean. If you got a torque monster sitting up front, you'll be breaking stuff and stressing stuff out.
As one who has seen more TCs in my career than I care to even try to guess at, I myself wouldn't go above 2000-2500 rpm. You should be able to flash stall your regular converter at 1800 or so if a smallblock. It depends on the torque of your motor also.
SINCE your not coming off the line in a 3300lb camaro at 3800 rpm with slicks and a 4 link.....I'd say tun a stock converter. Converters also make alot of heat with the slippage, and with a 383, you have a good bit of torque, with the 3.56. If things are anywhere near right, you should fry the skins out back easily.
In my opinion, and this is just my 2 cents, as light as these cars are, you really don't need a converter. A warmed up HP 350 with a stock Tc going thru a turbo 350 into a 3.56 rear.....it'd be hell on the street. You couldn't hardly get that thing to hook up! Unless you had slicks and some moose juice.........
Well, unless your Ted Brown!
Hey there Buster. I'd go a bit more still on the converter.At least a 2500 It will make the car more responsive and T-Buckets being so light you can put a higher stall converter in there and barely feel it. The higher stall will help the idle better , and stop the rpm drop when putting it in to Drive, and stop it trying to creep when idling. I had a 2200 behind a big block in a Pro /Street car, and you wouldn't even know it was there. I have a 3000 in my Model A truck now with a 383 and it's perfect. I had to upgrade the trans cooler though! make sure you put in the biggest one you can under there.
Buster
Member
I have already cranked engine up, idles great at about 1200rpms . Everything is ajusted now, had to change intake to dual plain . Couldnot seal intake leak with single plain, Wow lots of power. using holly 650 spredbore. thats reason i asked about stall on converter,since engine idles about 1200rpm. buster
Mike
Well-Known Member
When you are developing a new combination, the camshaft, compression ratio, the intake manifold, the torque converter and the weight of the vehicle are all joined at the hip. Read that line until you have it memorized, then write it on the blackboard 500 times.
Light cars do not want loose converters, unless the engine design is such that a loose converter is necessary to get the motor up into an RPM range where it is happy. And in order to reach that RPM range, a trans brake might become necessary, because vehicle weight will not provide enough resistance to make it happen. Read what Screaming Metal had to say.
If you do not already have a stock converter, look at the TCI Street Rodder Converter. In a T, it will likely be 250-300 RPM looser than a stock converter and that's going to be plenty for such a light car.
I realize the torque converter manufacturers need some way to gauge and compare converter stall speeds, but go back and read that sentence you were writing on the blackboard. If someone hands me a 3,000 RPM stall-speed converter, my question (and the *only* important question, BTW) is to ask what combination provided that slip speed. A very torquey 454 in an Impala? A mild street 305 in a Camaro? A mild 383 in a T-Bucket? Because (get ready, because there is going to be a quiz) those vehicles are all as different as night and day and they are not going to be able to achieve the same stall speeds. Pull that 454 out of the Impala and put it in your T-Bucket and the very same converter is not going to give you the same stall-speed as it did in the heavier car. Because the T doesn't have enough vehicle weight to pin the car to the ground. Yes, I've had people buy loose converters and then come back to gripe about the converter not stalling as high as it was advertised. Yeppers, and that is because their motors wouldn't make enough torque to pull a sick whore off a toilet seat.
If by "Thumpper cam", you are referring to the Comp Cams Thumpr[sup]TM[/sup] series of cams, that isn't much to be concerned with. Anyone who has been in the high performance aftermarket for 7 minutes has already talked to at least 3 customers who want a 3/4 cam for their car. We took an old cam that had some lobe damage and knocked the front four lobes off. I kept it under the counter at the speed shop and when someone asked me for a 3/4 cam, I would toss it up on the counter. There are only three camshaft profiles available - the RV cam, the 3/4 cam and the full-race cam. Screaming Metal, am I lyin' or dyin'? And no, I'm not joking. People would walk into the shop and base camshaft selection on, "gimme the biggest cam I can get to use with my stock torque converter." :suicide: And after reading that line, I bet there are going to be 100 people who are suddenly taking great interest in their shoelaces. Some people simply are not interested in building power in a particular RPM range, they just want a rough idle. So, Comp Cams decided to grind some cams to fill that market.
A Thumpr[sup]TM[/sup] cam in a 383 is going to be tamed considerably by the engine displacement. That same cam in a 283 would be a temperamental pig, but your inches will settle it right down. To a point where you will ultimately be happy you ended up with a dual-plane intake, because it's going to work a lot better than the single-plane would have.
You get all those sentences written yet? Good, now erase them and take this wet sponge and wash the blackboard. Because you're going to write them again. Camshafts play a hand in cylinder pressures, as do compression ratios. Camshafts are designed to be most effective in certain RPM ranges, as are intake manifolds. Engines want to be happy, so it is necessary to find a torque converter that will allow your vehicle's weight to make the motor happy. Then you get to find a tire height and rear gear ratio that will accomplish the same. Think about all of this, the next time the guy at the speed shop starts asking you questions before just tossing his own 3/4 cam on the counter.
And bear in mind that it is deadly simple to identify power loss in a car. Loss shows up everywhere, in the form of heat energy. You take a given quantity of gasoline, try to atomize it in a stream of air, squeeze it as tight as you can and set a match to it, to make as much heat energy as you can make. Then you move the majority of all that heat energy you worked so hard to create into the exhaust system and into the cooling system. Ever notice that torque converter manufacturers warn customers to install aftermarket trans coolers? That is because a loose converter will transfer more, yeah, you guessed it, heat energy into the fluid. The next time you drive your car, watch the temperature gauge rising as you drive. The energy you are using to heat up that 4 gallons of coolant is energy you are not transferring to the ground. When someone comes along with a car that has no radiator, you'll know that company has found a way to make their engine design more efficient, because there is no longer any heat energy being wasted to warm coolant.
Light cars do not want loose converters, unless the engine design is such that a loose converter is necessary to get the motor up into an RPM range where it is happy. And in order to reach that RPM range, a trans brake might become necessary, because vehicle weight will not provide enough resistance to make it happen. Read what Screaming Metal had to say.
If you do not already have a stock converter, look at the TCI Street Rodder Converter. In a T, it will likely be 250-300 RPM looser than a stock converter and that's going to be plenty for such a light car.
I realize the torque converter manufacturers need some way to gauge and compare converter stall speeds, but go back and read that sentence you were writing on the blackboard. If someone hands me a 3,000 RPM stall-speed converter, my question (and the *only* important question, BTW) is to ask what combination provided that slip speed. A very torquey 454 in an Impala? A mild street 305 in a Camaro? A mild 383 in a T-Bucket? Because (get ready, because there is going to be a quiz) those vehicles are all as different as night and day and they are not going to be able to achieve the same stall speeds. Pull that 454 out of the Impala and put it in your T-Bucket and the very same converter is not going to give you the same stall-speed as it did in the heavier car. Because the T doesn't have enough vehicle weight to pin the car to the ground. Yes, I've had people buy loose converters and then come back to gripe about the converter not stalling as high as it was advertised. Yeppers, and that is because their motors wouldn't make enough torque to pull a sick whore off a toilet seat.
If by "Thumpper cam", you are referring to the Comp Cams Thumpr[sup]TM[/sup] series of cams, that isn't much to be concerned with. Anyone who has been in the high performance aftermarket for 7 minutes has already talked to at least 3 customers who want a 3/4 cam for their car. We took an old cam that had some lobe damage and knocked the front four lobes off. I kept it under the counter at the speed shop and when someone asked me for a 3/4 cam, I would toss it up on the counter. There are only three camshaft profiles available - the RV cam, the 3/4 cam and the full-race cam. Screaming Metal, am I lyin' or dyin'? And no, I'm not joking. People would walk into the shop and base camshaft selection on, "gimme the biggest cam I can get to use with my stock torque converter." :suicide: And after reading that line, I bet there are going to be 100 people who are suddenly taking great interest in their shoelaces. Some people simply are not interested in building power in a particular RPM range, they just want a rough idle. So, Comp Cams decided to grind some cams to fill that market.
A Thumpr[sup]TM[/sup] cam in a 383 is going to be tamed considerably by the engine displacement. That same cam in a 283 would be a temperamental pig, but your inches will settle it right down. To a point where you will ultimately be happy you ended up with a dual-plane intake, because it's going to work a lot better than the single-plane would have.
You get all those sentences written yet? Good, now erase them and take this wet sponge and wash the blackboard. Because you're going to write them again. Camshafts play a hand in cylinder pressures, as do compression ratios. Camshafts are designed to be most effective in certain RPM ranges, as are intake manifolds. Engines want to be happy, so it is necessary to find a torque converter that will allow your vehicle's weight to make the motor happy. Then you get to find a tire height and rear gear ratio that will accomplish the same. Think about all of this, the next time the guy at the speed shop starts asking you questions before just tossing his own 3/4 cam on the counter.
And bear in mind that it is deadly simple to identify power loss in a car. Loss shows up everywhere, in the form of heat energy. You take a given quantity of gasoline, try to atomize it in a stream of air, squeeze it as tight as you can and set a match to it, to make as much heat energy as you can make. Then you move the majority of all that heat energy you worked so hard to create into the exhaust system and into the cooling system. Ever notice that torque converter manufacturers warn customers to install aftermarket trans coolers? That is because a loose converter will transfer more, yeah, you guessed it, heat energy into the fluid. The next time you drive your car, watch the temperature gauge rising as you drive. The energy you are using to heat up that 4 gallons of coolant is energy you are not transferring to the ground. When someone comes along with a car that has no radiator, you'll know that company has found a way to make their engine design more efficient, because there is no longer any heat energy being wasted to warm coolant.
Buster
Member
Thanks Mike best answer so far. I have a new stock converter, will try it first. I realley don't won't a T to race. just a show car that sounds good, not out to kill myself. I also have one that is 1600-2200. Just a couple hours to change if nessary. Have not drove car yet. Still working on body.wiring and lights. buster
Screaming Metal
Active Member
Dawm I love it when MIke gets on the Jazz! Hahaha.....
---- Screaming Metal, am I lyin' or dyin'? And no, I'm not joking. People would walk into the shop and base camshaft selection on, "gimme the biggest cam I can get to use with my stock torque converter." :suicide: And after reading that line, I bet there are going to be 100 people who are suddenly taking great interest in their shoelaces. Some people simply are not interested in building power in a particular RPM range, they just want a rough idle. So, Comp Cams decided to grind some cams to fill that market.----
Mike is correct! He's our Lovable Much Worship-ed Local TechnoGod! The cam is the personality builder in the motors. Choose the wrong cam, and you'll be miserable!
If your stock unit isn't slippery enough for you, try the other one, since you've got them already. I'd only go higher if you had a all-out Roller motor that won't idle under 1500 and it falls on its face at anything under 2500, a race oriented intake like a Victor, Jr, and a 750+ cfm carb.....like at least in a 10.5 full sized bracket car.
Remember, you can get a econo-altered and stick a mild 350 in at with a powerglide and run 10.30's all day long, and with tuning, high 9's.....YOU FLASH STALL THAT SAME CAR OUT AT 2500-3000, and you don't have wheeliebars, your gonna be looking for a good frame guy when it comes back down!
---- Screaming Metal, am I lyin' or dyin'? And no, I'm not joking. People would walk into the shop and base camshaft selection on, "gimme the biggest cam I can get to use with my stock torque converter." :suicide: And after reading that line, I bet there are going to be 100 people who are suddenly taking great interest in their shoelaces. Some people simply are not interested in building power in a particular RPM range, they just want a rough idle. So, Comp Cams decided to grind some cams to fill that market.----
Mike is correct! He's our Lovable Much Worship-ed Local TechnoGod! The cam is the personality builder in the motors. Choose the wrong cam, and you'll be miserable!
If your stock unit isn't slippery enough for you, try the other one, since you've got them already. I'd only go higher if you had a all-out Roller motor that won't idle under 1500 and it falls on its face at anything under 2500, a race oriented intake like a Victor, Jr, and a 750+ cfm carb.....like at least in a 10.5 full sized bracket car.
Remember, you can get a econo-altered and stick a mild 350 in at with a powerglide and run 10.30's all day long, and with tuning, high 9's.....YOU FLASH STALL THAT SAME CAR OUT AT 2500-3000, and you don't have wheeliebars, your gonna be looking for a good frame guy when it comes back down!
Screaming Metal
Active Member
And really, when you look at these cars and study them, thats all they are, street driven Econo-Altereds.......
Mike
Well-Known Member
Without a whole lotta SFI certification.
blownt
Member
the 1600-2200 converter will work with what you have in the bucket. But once you start to drive it and come to a light, you might not be too happy with it. You will prolly get a leg cramp from holding the brake pedal down so hard or else slip it into neutral while sitting still. You will be much happier with a 3000-3500 stall converter. Plus it is ALOT more fun to drive.
Mike I had to laugh at the 3/4 cam thing. We had a big cam, out some big diesel behind the counter, must have been about 5 feet long, and when that customer would come in and ask for the biggest cam made. Yep we pulled out this big diesel and cam and ask if that was big enough. The looks were priceless.
I have to agree with Blown T on the stall speed. I have tried the stock converters in Ts and they don't cut it. I have also tried some with just about 500 more RPMs and they still won't slip enough at a light. I have the 3500 stall in mine and while does not stall that high. That is how it was advertised, it actually stalls about 3000.
I have to agree with Blown T on the stall speed. I have tried the stock converters in Ts and they don't cut it. I have also tried some with just about 500 more RPMs and they still won't slip enough at a light. I have the 3500 stall in mine and while does not stall that high. That is how it was advertised, it actually stalls about 3000.
Yeah, I put a TH400 with a stock TC from unknown donor in my bucket and had to stand on brakes at stop. Replaced it with a B&M Holeshot TC, I think it was 2800 stall, and no more problem. The B&M unit was smaller than the stock. I thought about a 350 with lockup TC (GM made them in early 1980's), but heard it was a weak unit.
tfeverfred
Well-Known Member
I run a stock '84 305 SBC. I use a stock '86 tranny with the stock converter. Works great and I don't have to stand on the brakes. So....
jimbo01
Member
I have some confusion on what torque converter I should be using with the information that I have read. I will be running a stock 302, c-4, 3.73 rear end and steam roller rear tires. Would the stock converter work with this set up? I'd like the car to be responsive and be able to smoke the rear tires and not have to lay on the brakes at stop lights. This car will be a weekend cruiser around town with very little highway driving.
Well there you have it, completely different answers from one end of the spectrum to another.
I've always went conservative on torque converters especially on heavy cars, I went the other way on the T bucket because my thought was it was such a light car it wouldn't slip the converter too bad, so I went with a 3000. We will see soon, it is almost time to fire this combo up.
I've always went conservative on torque converters especially on heavy cars, I went the other way on the T bucket because my thought was it was such a light car it wouldn't slip the converter too bad, so I went with a 3000. We will see soon, it is almost time to fire this combo up.
roadmonster
Member
Did anyone else notice the carb? You do not want a Holley spreadbore in a T. It's made for a heavy car and even so is far inferior to a Quadrajet. Your vacuum signal is likely to be poor which will affect idle and shifting. That may be why it idles so high. A good vacuum signal at all times is what will make your T fun to drive. I have a brand new 2200 converter still in the box because my stock converter is so much fun. Sacrificing driveability for performance is no fun on the street.
Mr T Bucket
Member
I suppose for me, it's going to come down to my best educated guess. Finding that happy medium between the leg-tiring crawl at a stoplight and blowing all the extra fuel on board just to get it to move out of the garage, might take a try or two. Probably more aggravating than picking a stall rpm is picking a converter manufacturer, but available stall numbers may play into that decision too. 302 stroked to 331 with stock GT40 heads and a comp cam (262/270 & .493/.500) with a 1300-5600 rpm range and pre-planning for a blower down the road type of compression around 8.5:1 has me leaning towards the lower end of the stall range for the time being. It's probably the one part in my whole build that I haven't had a clear vision on what I wanted. Maybe that's the problem. That is, so far it's been about what I wanted in the T and the converter is more about how I want it to work. Factor in this manufacturer may be 500 rpm off from another and it's amazing that as many people get it right with the first stab as they do.
This would be a good tech article topic. TC's are a real pain. With a torquey motor and a lightweight car (i.e., most buckets), you either have to stand on the brakes at idle with a stock TC, or go with a looser one, knowing it's slipping like crazy, hurting mileage and making heat. GM made a lockup TC/tranny combo called the TH350C in the early 80's, but I've heard it's not as strong as a plain TH350, and I don't know if you can even find one, or anyone who knows how to rebuild or modify one. There must be a better way; do any of the new computer trannies have lockup TC's?
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