700 r4 swap in 71' questions

[joseph.a.hunt]

Hey I have a 71 c20 with a 350 and am looking into swap out my turbo 350 for 700 r4 I've heard its not as easy to swap out. Anyone have suggestions on what needs to be done?
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[JOJABOY]

one suggestion is to fork over $1800-$2000 and have a trans shop do all the work from start to finish. you can save about half of that if you do it yourself. i think a 700r4 with 4.10:1 is definitely worth the money. (plans are in my future) i think i am going to pay someone to do all the work just so i know it gets done correctly and get at least a 12 month warranty.

[SS Tim]

There are a lot of threads on swaps. Couple of things to remember are that any used O/D trans is a core until proven otherwise. If you have a lockup converter trans make sure the lockup is working. KNOW how to adjust the T/V cable before ever trying the trans.. The driveshaft will probably need to be shortened. Finally it needs a good cooler in addition to the radiator liquid to liquid loop.
What engine/trans. was your truck built with and what does it have now?

[stomper]

My biggest challenge was the attachment of the TV cable to my stock Q-jet. The geometry has to be perfect. I ended up using a little $2 spring from Monster Transmission between the end of the cable and the swivel clip thing on the ball stud. It made the stroke shorter and was just what I needed.

Oh and if you do it yourself, get a trans line pressure gauge. I didn't think I would need one and I wish Id have had it from the start. Most of them are expensive but Harbor Freight had an acceptable unit.

[ScottG]

I just did this swap in my '67 a few months ago. A lot goes into it, more than you'd think. I got VERY LUCKY, and picked up a used one that had been rebuilt from a school district employee for 200 bucks. You will probably need to move the crossmember (mine had a TH400, much shorter). Shorten the driveshaft. This measurement is critical, and must be done correctly. I also used the Bowtie Overdrives EZ TV cable kit. Made adjusting the cable so much easier. Cable adjustment, and fluid level or very important!! If your not comfortable tackling these things, then having a reputable shop is the way to go.

[Z10]

I have a friend who owns a transmission shop. He tipped me off to a GM Certified 700R4. Purchased it from my local Buick/Cadillac dealer. Ordered in one from a 90 model Corvette. Paid $1550 delivered. Comes with a shift kit and a 2000rpm stall converter. The only hitch is you need a 700r4 core. So, off to the local salvage yard and picked one up for $75. My friend tells me that the adjustment on TV cable is critical. 1/2" off and you can toast a transmission. Thankfully he has volunteered to come set it after I get it installed.

[long67]

I also really want to do this swap. I was quoted 1800 to 2000 drive in drive out by a shop here. seems reasonable to me.

[formikaus]

I did this swap and there was a little work involved. I grabbed another trans crossmember and bolted it in with the swap. Remember this, 700r4 is longer than a 350 or 400. It also depends on what you have now. If you have a V8, your driveshaft is longer than a 6cyl. I had a V8 in mine so with the longer 700r4, I used a 6cyl. SWB drive shaft. The cable is the life line of this trans. IT WILL NOT HAVE OVERDRIVE WITHOUT IT. The cable I had was stretched a little over time, so I pulled the slack thru the clip that goes on the carb and added some 1oz split shot fishing weights. Hey, it did the job!!! With this cable you can set your shifting points, I have mine to shift into second around 12 - 15 miles per hour. With a stock 350, 700r4, and 308 gears i was getting 18mpg's and around 2300 - 2400 rpm's at 70mph. Definitely worth doing the swap!!!

[Wrenchbender Ret]

I put one in my 70 stepside a few years ago. It has 3.08 rear gears & 350 engine. It drives beautiful. Eases down the high & you cant hear the engine. Gets about 18 MPG.
I did it myself because I wanted it done right.

[myyamr7]

I just met with my local transmission shop a couple days ago to talk about a 700R4 swap in mine. He talked me into a 200R4, said they are a bit lighter, takes a little less power away from the engine, and it's only 3/8" shorter than the TH350, so no driveshaft work needed.
He also said to put an updated valve body in it, the ones out now take over most of the work of the T/V cable...while you still need it hooked up, getting the perfect geometry from the carb to the cable isn't as important.
With the valve body, a new non-lockup converter, and a full rebuild, it's going to cost about $1k and me intalling it myself

[Z10]

Originally Posted by myyamr7

I just met with my local transmission shop a couple days ago to talk about a 700R4 swap in mine. He talked me into a 200R4, said they are a bit lighter, takes a little less power away from the engine, and it's only 3/8" shorter than the TH350, so no driveshaft work needed.
He also said to put an updated valve body in it, the ones out now take over most of the work of the T/V cable...while you still need it hooked up, getting the perfect geometry from the carb to the cable isn't as important.
With the valve body, a new non-lockup converter, and a full rebuild, it's going to cost about $1k and me intalling it myself

Unless built properly the 200r4 is also much weaker than the 700r4. So, if you're not going to be pulling anything and you have modest power, it should be ok.

[kaycee]

I just did this last week still trying to get TV cable set Everything works good except I can't get the dam thing to kickdown.I got a trans that was mild rebuilt with conv. for $700,I have probabally close to $900 into it now and may have to get a specefic cable bracket assym. +$150.I have done everything on my truck paint,body work,engine ,interior ,frame off mods and this freeking trans swap has tested my patients the most.I live on a very tight budget so I could not afford to have someone else do it just hope I can get this dialed in before to long or the TH-350 may go back in