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Th350 to 700r4

Holey76 - Square Nut

Holey76 - Square Nut

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Hi all.
Im wondering how many of you have swapped a th350 for a 700r4, and what your thoughts are on the end result, generally speaking.
 
I like the 700R4 better than the TH350 in 2 ways. Lower 1st gear makes for better launch. Overdrive helps a good bit if the rear axle ratio and tire combination is in the proper range.
The 1-2 gear split in the 700R4 isn't as nice as the TH350, however.
I swapped my C10 from TH350 to 700R4, and I have two K trucks with the 700R4, but they never had a TH350.
 
any issues with the 700r4 ? ive heard some ppl say its riddled w problems and unreliable.
the reason i ask, is that i just built and instaone. havent fired it up yet, but also built a 375hp 425flbs 350 to mate up. im a bit nervous that the trans wont do well.
 
(i could have sworn i replied, but its gone) ive heard ppl say it unreliable. ijust built a new one, and havent fired it up yet, but about the plunk a new 350 in front of it, sitting at 375hp and 425 ft lbs. im jervous and nerky that the 700r4 may not do well...

on a side note, i saw your post about stopping in glenwood, are you in western co or eastern ut ? (am in gj)
 
Holey76 said:
any issues with the 700r4 ? ive heard some ppl say its riddled w problems and unreliable.
the reason i ask, is that i just built and instaone. havent fired it up yet, but also built a 375hp 425flbs 350 to mate up. im a bit nervous that the trans wont do well.
Click to expand...
I haven't had problems with any transmission that I have had built. Stock type builds are not the way to go. This usually fixes the original design issues, but improper builds can still happen.
I do make sure to set the TV cable properly and I always go for a shift kit. I have one that has been behind a mild big block for 40 K miles or so.

I'm in GJ.
 
Have you researched what it takes to swap a 700R4?
It has a different tailshaft length for 4x4 when compared to a TH350.
 
Ya, i bought a shorty (11.18"? I think) from offroad design. No problem mating to no203. I had to move the crossmember back 1.6", have both driveshafts modified, the usual... How much does your rig with the BB weigh ?
 
I did add hd and xtra clutches, sungear, wide band, large servo piston etc etc, but still kinda wondering if the 700r4 will handle a hard launch in an old k5 (?5k lbs) but after you saying youve had no issues, i guess the guys that did have issues, may have had weak builds, too many horses (huh ??) Or too heavy vehicle ? Idk
Holey76 said:
Hi all.
Im wondering how many of you have swapped a th350 for a 700r4, and what your thoughts are on the end result, generally speaking.
Click to expand...
Fast trucks & slow women.
 
I have been running a stock 700r4 in a 7000 pound k5 for 16 years. Never an issue. But @6872xtc will confirm that I am super easy on my truck. No HP and a smart right foot has made the drivetrain last.
 
My big block truck weighs 5100, my '90 Jimmy is 5600.
My '70 K10 has been to the dragstrip here once, burnout contest in Olathe once when they used to do that. I showed a couple of cars in Moab how to do a proper burnout... a couple of times..
My '72 C10 has a small roller cam in a 406 small block and hasn't had a problem. It weighs 4200, IIRC.
I believe that you should be fine, as long as you pay attention to TV cable adjustment, keep it full of oil and verify proper convertor lock-up in 4th.
 
That's all sound advice I'm not a huge fan of speeding tickets, so this won't be pushed real hard. I believe the tv cbl is right, but I'll fine tune it when i get it fired up. As far as the lockup, I'm using a B&M controller, so I'll set the speed for around 40. I have to admit, my burnouts are out of practice and i may need to do a cpl once in awhile, just to make sure i haven't forgotten how
Always loved the 70 ck10 trucks. I wanted one as a kid
 
When you swap a th350 for a 700r4, the transfer case goes rearward 2". So the tc linkage doesn't reach anymore.
So cable shifter ? Or extend linkage ? Can't see the linkage at the floor shift, cuz it's obscured by the transmission. How do the rods detach from shifter ?
 
700r4's will only hold up to a blown sbc, if you drag race them, and also enter a drifting event! LOL This has only been proven in a 3500 lb Monte Carlo, so you might want to hold off on the drifting in the Blazer.
 
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