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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: JohnnyPopper on October 21, 2020, 06:34:38 pm
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I looked into swapping out the TH350 to a OD, move the cross member, etc, north of 2-2.5K
Had the brainiac idea to change out the Diff from 3.73 to a 3.08
I know there is a mid point, what 3.48? but I don't think I would see much difference.
It's a daily, I don't offroad, I don't haul loads, just don't like doing 3-3500 rpm to keep up with traffic.
While here, does anyone know the max torque rpm for a crate Goodwrench 350?
I'm first to admit that I don't know how far down the rpm will drop, so if this is a fools errand, please flame away!
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Keep the 3.73:1 and change to a 700R4
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Thx VZ, that's what I think the ultimate solution is.
I faintly recall a comment about there being a year range where that trans was bad-is that on your radar?
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87 up are the best years but that was 33 years ago so, finding a good used one is just a bad gamble. Buy a reman unit, they come with 3-4 year warranty
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I'm a "deep gear" guy. While I don't think that most folks need something like 4.88s or 4.56s, I would probably never go any higher than 3.73s on anything with body-on-frame construction. For me, it's not a hauling or offroading thing. It's an enjoyable driving experience thing. My Mom has a 2008 Tahoe with the small LS and high gears. It's a great and reliable vehicle. Unfortunately, with the really small V-8 and highway gears, it'll barely get out of its own way. Nothing even starts happening 'til about 3000 RPM.
I agree with you on the 3.73 versus 3.42 thing. I don't know that you'll be able to tell a difference. I have two '86 K30s, one with 4.10s and the other with 3.73s. Both get the same fuel mileage (give or take a tenth or two of a gallon, here or there). And, the only time I can tell a difference is when there's a load behind them. Other than that, they feel pretty-much identical.
I was in my teens in the 80s. And, my mind has never relinquished the thought of the 700R4 being a turd. So, to answer your question, if something is engrained in my head that deep, there must've been a few years that were less than desirable.
My only experience with the 350 was knowing of a guy who made about 300-325 ft/lbs. with the Goodwrench 350. I believe he was running a Quadrajet. If I remember correctly,...and don't quote me on this...I think it was way up there, like in the 3500 to 3800 RPM range.
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Just Curious: Can anyone state what the rpm would be between differentials in a 3.73, 3.48, or 3.08:1? Sorry for the ignorance, I was never schooled on this discipline.
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https://purperformance.com/p-29669-rpm-calculator.html
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I was in my teens in the 80s. And, my mind has never relinquished the thought of the 700R4 being a turd. So, to answer your question, if something is engrained in my head that deep, there must've been a few years that were less than desirable.
My thoughts exactly.
I know I'm a little late responding to this (sounds like JohnnyPopper is already involved with the gear swap).
I know technology has come along way since the 80's. Like Vile said, some 700R4's come with a great warranty now, but my mind is still stuck in the past.
Some will cringe at this, but in the early 90's I replaced my 700R4 in my 88 Jimmy with a turbo 350. The 700R4 was due for its 3rd rebuilt and I said enough is enough.