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Discussion Starter · #1 · (Edited)
I just bought a 68 camaro with a 454 (somewhere between 500 and 600 hp) running a 700r4 transmission. I have no idea if the tranny has been built up or not. I have been getting mixed opinions on whether or not the 700r4 can handle the torque of a big block. I could get the 700r4 built up by a local shop for about 1300 that they say will handle the 454 with a 3 yr warranty. For some reason i am stuck on 3.73 gear ratio especially if I do go with the 700r4. I did find a shop that i can get a th400 for about 700 that should handle the 454 with ease. If i do go with the th400 would 3.73 be to much or would i be a little better off going with the 3.55. What gear ratio would you guys go with? I'm pretty sure i will have to adjust the driveshaft if i switch trannys which I will be doing because I need to rebuild and put a different rear end in as well. I only intend to use the car for weekend drives and the occasionally red light romp.
I would love to have your guys input. Thank you
 

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I have a 2nd gen with a pretty stout 385 sbc, 700R4, with 3.73 gears. Unless things are a lot cheaper where you are, I know from experience that a $1300 rebuild in Chattanooga, TN will not stand up to 500lb torque with 275/40x18 tires. Not saying that it doesn't have anything to do with my driving habits though. Yes, the 700R4 can be made to live in that condition, but it will cost a bit more. And I really do love to click it into overdrive, the lock the torque converter for highway cruising. Should mention that a $400 Evilbay lockup converter won't last long either.
 

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I'm running a sturdy 454, built 700r4 and 3.73:1 12 bolt posi in a '68 Firebird. Love the combination, both OD and lock up. Ran a big block with turbo 400 and 4.11 gear previously. Not much of a highway car. If built right, especially if only going to run street tires, a built 700r4 will live. Replace sun shell with an aftermarket piece.
 

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Yes, the 700R4 can be made to handle it. Can your guys do it for tat price Anyone’s guess but if they know your use case and will warranty it for 3 years go for it. As far as rear gears that depends on how you will use the car. If this is primarily a street car, I think 3.73s are to low because the 700R4 has a pretty low first gear. A good rule of thumb is to multiple you first gear ratio by the rear end ratio and compare the product to 10. If the product is over 10, your final ratio is to low. For you I, 373 x 3.06 = 11.4. Going the other way, 10 / 3.06 = 3.27. That may be pretty a pretty tall gear so you can also use tremec’s speed calculator to to see what your speed is at a certain cruise RPM. It doesn’t have ratios for the 700r4 but you can change them. With a 26” tall tire with 3.73s you are turning just under 2400 rpm at 70 mph in OD. That’s pretty good so 3.73s would work pretty good unless maybe you are wanting to cruise in the 80mph range. The only “issue” with 3.73s on the street is that 1st gear almost useless with the low first great of the 700R4. That was my issue what I had 4.10s with my Muncie. With the torque of that big block and the really low gears, you might struggle to find traction on the street if you get on it. But, if you do it will generate excessive smiles per hour. :). I’d say, leave the 3.73s in for now, rebuilt the 700R4 and see how you like it.
 

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Discussion Starter · #5 · (Edited)
Thank you everyone for your input. I just came across a th400 that i picked up for 400 bucks. I think I am going to go that route. In my little experince and just listening to everyone's input on the issue the 700r4 just seems like a bad investment for me. If the one I currently have was working flawless this conversation might change. However, I am in a position where I am going to have to invest money into a tranny. I think the th400 will fit what I want to do more than what the 700r4 will. I am not concerned about crusing down the highway. I am looking for what i call the wwrr (weekend warror redlight romper) I am going to coin that phrase hehe lol😀. I found a local guy that is kinda a legend rebuilding trannys that can rebuild that th400 for 650.

So now that I am for sure going with a th400 I am now left with another question. Which torque/stall converter should I go with? I was thinking about a 2400-2500 rpm
 

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Discussion Starter · #6 ·
My dad has a 69 nova running a 383 stroker with a th400 with 4.10 gears. I love the way that is set up. Just so you guys have a clearer picture of what my main goal is.

Thanks again for your input Bruce, CorkE and 68fbird
 

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Your welcome. Good luck.
I changed the 4.10 for the 3.73 before swapping out the turbo 400 for the OD. A little more highway friendly but not much difference in fun factor.
Match stall speed to cam duration if you know. Any idea what was in the car for stall?
 

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Discussion Starter · #8 ·
Your welcome. Good luck.
I changed the 4.10 for the 3.73 before swapping out the turbo 400 for the OD. A little more highway friendly but not much difference in fun factor.
Match stall speed to cam duration if you know. Any idea what was in the car for stall?
Unfortuantly I do not know what stall it came with. I am not sure even on the cam duration I asked the guy i bought it from what cam he put in but he couldnt remember.
 

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So now that I am for sure going with a th400 I am now left with another question. Which torque/stall converter should I go with? I was thinking about a 2400-2500 rpm
Unless you have some radical cam that needs to spin to 7k rpm to make its power....a 2400-2600 stall is very common for modified (cam) motors

Personally I stay on the smaller side (2200) stall. Once you get past that, IMHO, you should consider a larger or additional external trans cooler

I have a Hughes TC
 
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