I've got a 350 with three speed turbo 350. I would like to get a four speed tranny because I do a lot of highway travel. Should I stick with the turbo 350 and would a four speed 350 still work with my current transfer case or would I have to replace that too?
CK5
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What tranny should I get
- Thread starter google
- Start date
beater_k20
Banned
hmmm... how ironic is this... SEARCH. topic has been discussed several times on swapping trannys. there is no such thing as a "4 speed 350" your only cost effective option would be a 700R4/4L60. if you wanna lay down some coin, you could go 4L60E/4L80E, or switch to an NV4500 5 speed manual.
4l60e or 4l80eneeds computer to run it. and throttle position sensor and a map sensor. if you have t.b.i. setup for fuel it will be much easyer to put in than carbed. if 700 is what you want then can be carbed or efi.
Ever since I asked the question, I figured I would get the answer that there is no such thing as a 4 speed 350. Okey then, how about a way to save on gas without changing the tranny? The tranny is strong, but being that I take the highway to work (no, there isn't another option) I get around 6mpg romping down the road at 4500-5000 (I have no tac) rpm. If the answer is !!!If you can't afford it you shouldn't have gotten it!!!, save it. I can afford it, I would just rather spend the money on a new wench or something. hehe. Any sugestions on that one?
beater_k20
Banned
google said:
a new wench eh? saving gas money to buy prositutes sounds like a hell of a plan to me.
seriously, we have to know what we're working with first. gear ratios, tire sizes, internals on the engine. hell, even an engine size would be a reasonable start.
ok then, here it is. 350 from a vette (that's what I was told anyway) with turbo 350 tranny. I found today that my transfer is a 208... I hear it's good for low end... anyway, i'm currently running 33 12.50, but would like to upgrade in a few months after getting a lift in there. Maby 36in 
I haven't been able to take this thing out wheeling yet. Just got it a couple weeks ago and i've been working mad OT without a day off since. I don't know what the gear ratio is, but the thing has a lot of get up and go. I had a 2000 dodge ram with 360 in it before this and after getting 36in tires, it hardly moved with stock ratio. This will git up and go faster than my dodge did with stock 31s. What I want is something that I can wheel with, but I can still drive on the highway without sounding like a nascar behind the pace car.
Yes, it is shifting into 3rd with no problem. The tranny is in great shap, but not what I need or want for daily highway driver.
I haven't been able to take this thing out wheeling yet. Just got it a couple weeks ago and i've been working mad OT without a day off since. I don't know what the gear ratio is, but the thing has a lot of get up and go. I had a 2000 dodge ram with 360 in it before this and after getting 36in tires, it hardly moved with stock ratio. This will git up and go faster than my dodge did with stock 31s. What I want is something that I can wheel with, but I can still drive on the highway without sounding like a nascar behind the pace car.Yes, it is shifting into 3rd with no problem. The tranny is in great shap, but not what I need or want for daily highway driver.
mudslinger99
1/2 ton status
beater_k20 said:
Now that is funny right there
He did say he has got a 350 motor and a 350 tranny but that is about it...
I hope that your guestimate of 5000 rpm is way off or, {a} you must be running some terrible gears {b} your running that thing wide open {c} you need to shift out of 2nd gear
As far as getting 6 mpg sounds like you should start with a tune up, plugs,wires,cap you know the standard stuff... Changing to a overdive tranny will gain you a couple more mpg because it will lower your rpm at highway speed... But it is not like it is going to double it...
A 700r4 would probably be your best bet to get you overdrive... But you will have to make some drivetrain modifications... How much or how little you would have to change will depend on what you have now..
It's got a new rebuild on the motor and new tune up using all the good stuff. MSD, acdelco, taylor etc.. And last, there is no reason to make fun of me. I don't know alot and i'm not afraid to admit that. That is why I ask the questions. I want to learn and keep this my project instead of a mechanics paycheck. Thanks for the post, most unhelpful
beater_k20
Banned
mudslinger99 said:I hope that your guestimate of 5000 rpm is way off or, {a} you must be running some terrible gears {b} your running that thing wide open {c} you need to shift out of 2nd gear
Changing to a overdive tranny will gain you a couple more mpg because it will lower your rpm at highway speed... But it is not like it is going to double it...
actually, if he's running 33s and stock gears (most likely 3.08s), an overdrive trans is a BAD idea. the 3.06 1st gear of a 700R4 will feel great down low, but at cruise speeds you'll be lugging the motor. not good for the motor or the trans, and milage will suffer.
you need to establish a good baseline. compression test on the engine, as well as a leakdown test. cap, rotor, plugs, wires, a coil wouldnt hurt, change the oil and filter, as well as the trans filter if it hasnt been done in the last 6,000 mi or so. also, change your fuel filter, and run a few tanks of GOOD gas (premium
) through it. see how it runs, and how it does on milage then. then start with tuning it. set your timing, and then adjust the carb. i KNOW you can get better milage than that, i get double that with my tired old K20 with a snowblade on the front. BTW, i've got 4.10 gears, and 30-31" tires on it.chevy400hp
Registered Member
i have 350 with a th350 and 205 and 410s and 33x1250 and mild cam in it and manual,big carb,after market intake,headers,and free flowing muffer and i get about 10.5 to 11 mpg on the highway and the 3000 rpm
