So I have a 71 Skylark with a 70 buick 455 and a turbo 400 longshaft. The car originally came with a 350/th350 but all i can find around here is turbo 400 longshafts Any ways I go to jegs to buy a 12" 2000 - 2300 rpm for $104.99 or a 12" 2300 - 2700 rpm for a $134.00 Which one would I want? for basically a good street car that we will probably run hard every once in a while. 3.73 gears Also Jegs suggests bor big block applications to get a 10" converter but they are like $400.00, won't the 12" work? Thanks!
coan has a sale right now for 10" converter for 350 for a 450+ dollar converter dont get a cheap converter... do a search for (baloon converter) (thrust bearing)
Did you do some work on the engine for more power (cam, head work, headers, etc.) or do you plan to do work like that in the future? If not, I wouldn't worry about replacing the stock converter at this point. With that gearing and a stock converter, a healthy '70 455 will do just fine if you have some tires that bite. Devon
No engine was rebuilt to stock, but I don't have a torque converter now I have to buy one, so I'm cool with a 12"? Which stall should I get? the 2000 - 2300 rpm or the 2300 - 2700 rpm?
The ONLY reason to change to a non stock torque converter is if you have gone to a cam that raises the power range of the engine sufficiently to need a higher stall. If the engine is stock, you want a stock converter. You will gain nothing by putting a higher stall converter in, and you will not enjoy the slipping feeling you get by installing a looser converter. Anyone who buys an off the shelf converter is rolling the dice IMHO. It may be OK, and it may not. No converter will stall the same in ANY combination. That is why they specify a stall range, and that may not even be accurate. Stock engine needs a stock converter, 1400-1600 RPM.
Cool thanks guys! Do you guys think that long shaft th400 will be fine? i can't find a short shaft and i'm going to have to have the driveshaft shortened anyways since mine is for a 350/th350 , I have enough holes in my frame for the tranny brace right? for a long shaft. I can't find a short shaft anywhere cheap
The biggest kept secret is the 13" converter from a 70-73 454 Corvette. Every Stage 1 should have had these but only the Corvette did. They stall about 2200-2400 stock and modified about 2800RPM which would be too much for your stock engine. But stock they would drive very well. Chevy built these because the 454 peak torque was at a higher RPM then Buick with 510' #'s at 2800 RPM. These are so good that I had 2 special ones built for my own use. (Sorry I can't tell anyone what was done or I would have to ... well you know) Thats right 13" for high performance, especially street use. When you have 500HP then think about something else. My brother has built every trans from a tiny toyota to large semi truck autos and sticks, for dragster and other race cars for 37 years. His dragster trans have never had a failure. Not too many can say that. He knows what he is talking about. Save your money and see how cheap you can buy a totally stock converter for a 70-73 (I think 73 was the last year) corvette. I believe that it had only 2 rows of weld beads instead of 3 like the other 13" converters for all other GM cars. Some one at your local trans shop might be able to find you one but make sure it only has 2 rows of weld beads. If you don't have the money don't go switch pitch either. There is a purpose for all that. I have 3 of those also. ( again not for sale) ps. a 12" converter will always slip more at cruising speed than a 13", so don't waste your gas money either!
Dont buy a cheap converter no matter what you end up getting. My suposedly TCI/3200 (bought at a swap meet for 100.00)converter gernaded during a burn out in he water box and flushed metal all through the trans.
Sure, the long shaft will work, you'll just have to shorten the drive shaft. The only other concern may be pinion angle. I would check it, and if it needs to be adjusted, you need to buy a set of rear upper adjustable control,arms.
I agree that you dont "need" a big converter with a stock build. But.....its false to say that you will gain nothing by going with a larger converter. If this were an "all out" drag racing application, the best converter stalls around peak torque. Either a couple hundred rpm before peak torque, or a couple hundred rpm after. Depends if your heads up racing or bracket racing and where you shift(concerning shift recovery) as to whether the best converter is slightly before or after peak torque. Yes...this isnt an all out race car for sure, but there are still plenty of gains to be had if you want em. Even something that stalls 2500 rpm would be a big difference. buicks very own switch pitch transmission proves this very well. The cars they were equipped with get around just fine with a stock converter....but they still accelerate better, even as a stock engine, when the throttle is depressed enough to toggle the higher stall speed. Whatever you do....buy a good converter. Jegs makes a good converter....but not the hundred dollar converter. their XHD stuff is good. Id personally use a 2200-2400 converter with this. Dont worry about slippage with a good converter. I drive around a 4000 stall speed 9.5 inch converter. Its nice and tight and only stalls up hard if you really mat the throttle. Drives darn near like a stock converter during mild throttle street driving. Its no cheapie. Id talk to Coan, Edge, Ultimate converter concepts, TSI(not tci) PTC or that jegs XHD just to name a few that could make you a good product in the 300 some dollar range. Its well worth the investment. no need for anything huge here but I wouldnt put junk behind a torquey engine, and if your buying one....a little bit of stall speed over stock will add some pep without being problematic. as stated you are much better off calling one of these companies and having them set you up with something that fits your needs. a 2500 converter for example acts largely different if you use it in a vega with a higher strug 355 vs a heavy car with a torquey, large cube engine. the "rating" of a converter is just a general guideline. Input toruqe and rolling resistance(vehicle weight) throw a wrench into things. You want a tight converter that has the ability to stall up a little under heavy throttle.
There's a recent thread on the subject of tailshaft length at http://www.v8buick.com/showthread.php?241639-350-TH350-swap-to-a-455-TH400-Tailshaft-Length. As you see, there's not a consensus on the situation. However, for absolute peace of mind I got a short tailshaft and replaced the longshaft on my TH400, even though it had just been rebuilt and the last thing I wanted to do was tear it apart. Didn't have much trouble finding a shortshaft for a reasonable price, although it may be a different story up there in Big Sky country where everybody rides horses.
Greg, I agree with most of what you said, but if he buys something off the shelf, I think there is a good chance that it will be too loose. If he wants the best of both worlds, he has to spend some money and have a converter built for the engine. A converter that stalls a bit higher, and is also efficient (built tight for the street) is going to cost more as you said. For a completely stock engine? I guess that is up to Todd. A good converter will definitely show it's worth at the track, but on the street, he might be better off with a stocker. A good converter is going to smoke the tires for sure. Gonna need sticky tires all the time.
Greg, I agree with most of what you said, but if he buys something off the shelf, I think there is a good chance that it will be too loose. If he wants the best of both worlds, he has to spend some money and have a converter built for the engine. A converter that stalls a bit higher, and is also efficient (built tight for the street) is going to cost more as you said. For a completely stock engine? I guess that is up to Todd. A good converter will definitely show it's worth at the track, but on the street, he might be better off with a stocker. A good converter is going to smoke the tires for sure. Gonna need sticky tires all the time.
oh no doubt about that. I know my post was a little long but I did put in there at the end....definitely dont just buy something. Call so they can get you what you need for that very reason. He needs a tight converter for this kind of app, and although you dont "need" a higher stall speed....if you wanted to add a little bit of stall speed youd want to be sure you dont overdo it. thats why its best to call em up and discuss your needs so you dont end up with something too loose for your motor. truth be told if you wanted to stick with a stock converter, Id probably want an ACTUAL factory converter as opposed to a hundred dollar cheapie from anywhere. Id be willing to bet a real factory converter will be more reliable than the bottom dollar aftermarket ones. As far as the tire spin thing....haha I guess thats all subjective. Not that I built mine with the sole purpose of frying the tires, but it does smoke them easy and I call that a good problem to have. If you want something maybe a little more tame and/or predicable, definitely nothing wrong with that but its good reason to keep the converter close to stock.
