TH-350/700r4 swap

[colt45-2007]

I got a buddy of mine that just bought an 83 custom deluxe 2wd 305/TH350... He found a 350/700r4 for cheap out of an 88 c1500 like mine and he's wondering what all he needs to do to make this work, the motor swap will be relatively simple I know, hes gunna take the intake and quadrajet off the 305 and slap it on the 350 and etc but he was askin me what all he needs to make the 350 to 700r4 tranny swap.... Now I have an 88 so I may be wrong on these older trucks but I told him he would need a shorter driveshaft, maybe have to move the tranny mounts and possibly a different crossmember, if this is true what would be the best truck/car to get a driveshaft and crossmember from? I also told him I wasnt sure how the column shift would work going from a 3speed to 4speed.....

Any Info And Past Experiences "Good Or Bad" lol Would Be Great, Thanks

[MoFaster]

The driveshaft is the same and he can use the same crossmember. He will have to move it........ back I think, but he can use the stock cm. I just took a 700r4 out of my 78 and put a 350 back in it. The tranny had a man. lock out valve (instead of the elec. one). Used factory shifter. The kick down cable has a lil diff. mount, but he should be able to pick one up at a speed shop or auto parts store. Hope this helps ya out.

Bill

[kelgar50]

Just a little FYI you cant put the intake from a 83' sbc on anything later than a 85' sbc.The heads from 86' on are cut at a different angle on the mounting surface for the intake there for the intake will not bolt up right.Your friend will need a intake from 86' or later or he would have to put his heads off the 305 onto the 350 which would work but also raise the compression ratio.

[68c10owner]

Originally Posted by MoFaster

The driveshaft is the same and he can use the same crossmember. He will have to move it........ back I think, but he can use the stock cm. I just took a 700r4 out of my 78 and put a 350 back in it. The tranny had a man. lock out valve (instead of the elec. one). Used factory shifter. The kick down cable has a lil diff. mount, but he should be able to pick one up at a speed shop or auto parts store. Hope this helps ya out.

Bill

It depends on what th350 he has. The short shaft which is more common in cars would need a driveshaft change. The long shaft th350 is close to the length of a 700R4 if I remember right. The kick down cable is actualy a TV cable( throttle valve) and need to be adjusted correctly for the trans to shift right. The linkage should work find but the gear indicator won`t be correct. The cooler lines will probably work, the crossmember will have to be moved back some and you`ll have to either buy a lock up kit or just run a toggle so you can lock it up whenever you want it to.

[Albatrossian]

If he had a long tail TH350(9-1/4" tail), the driveshaft will work. If he has the short tail, he'll need a driveshaft about 3" longer. The crossmember will have to be moved about 2". He'll have to drill 1 hole in each frame rail for the bolts. Make SURE the TV cable is adjusted correctly or he'll be putting the TH350 back in after about 50 miles. I put a 700 in my truck and it lasted 45 miles before 3rd and 4th were wiped out because of a mis-adjusted TV cable. If his 350 is stock, it should last as long as the TV cable is adjusted right. The 700 won't handle alot of power stock, it'll have to be upgraded for anything other than stock power levels. Been there, done that too.
Good luck!

[bradf74]

try 700r4.com They specialize in this kind of swap. I did this into my 68 camaro and love it. I used their TV cable sytem and trans internals.

[MoFaster]

Yeah I was just assuming he had a long tail since it came out of a truck. My 700 was behind a 400 w/ about 375-400 hp for a lil over 2 years. I did have an aftermarket converter, corvette servo, Bill Younger stage ll shift kit, heavy duty clutches, man. lock out valve, and he did a little bit of work on the valve body. I think it would have lasted longer, well I know it would have, but I started spraying it and that was the end of it. (sprayed 200 w/gemimi twin plate)

[colt45-2007]

I had no clue at all about the heads being different on 86 and ups, did they change when everything swapped from 4bbl to tbi? As for the TH-350 I feel purdy certain that its the short tail being that its a short bed 2wd but maybe we'll have a stroke of luck and it be a long tail lol... I had a guy at a parts store tell me that a two peice drive shaft out of an 88-98 extended cab would work.... I seriously dont see that working out though.... Well everything seems relatively simple for the most part but hey its not worth workin on if it doesnt give u a challenge haha, It would be a lot more simple if he would just leave the 350 tranny in but he wants gas mileage so thats why hes gettin the 700r4... I'm sure I'll be back on here with questions this weekend

[78 Chevyrado]

Here's some good info. The site wasn't coming up when I put this like here, but try again later, This site has what you need.

http://www.rowand.net/Shop/Tech/Auto...issionSwap.htm

[Damien]

Most, if not all, pickups came with the long shaft transmission, so I think you are going to be Ok on the driveshaft issue.

"Up through 1986, the bolt pattern on all small block Chevy engines was exactly the same. From 1987 through 1995, the four center mounting bolt holes (two on each side) were at a different angle. This change applied only to Chevy cast iron manifolds. The aluminum manifolds were the same. Whereas every other manifold company has a few additional
models to fit these later heads, every one of Professional Products' SB Chevy manifolds will fit all years up through 1995.This is accomplished by slotting these four center holes and supplying drop in bushings which change the bolt hole angle to fit the late heads. On the early heads, you simply use flat washers on the slotted holes. Note this does not apply to the Vortec manifolds, which do not have the four center holes." http://http://www.rjays.com/Engine%2...Intakes-02.htm
Here is a link to an ebay auction for just the adaptor bushings.
http://cgi.ebay.com/ebaymotors/ws/eB...6474&viewitem=

[Damien]

Originally Posted by 78 Chevyrado

Here's some good info. The site wasn't coming up when I put this like here, but try again later, This site has what you need.

http://www.rowand.net/Shop/Tech/Auto...issionSwap.htm

I don't think everything in the linked site above is 100% correct. I did not read through this entire webpage, But there are TH350s with lock up converters. One of his tables says the TH350 does not use a lock up converter. The guy also stated that he was going to use a "600r4/4l60e".

[78 Chevyrado]

Originally Posted by Damien

I don't think everything in the linked site above is 100% correct. I did not read through this entire webpage, But there are TH350s with lock up converters. One of his tables says the TH350 does not use a lock up converter. The guy also stated that he was going to use a "600r4/4l60e".

I'm sure 600r4 is a typo. There may be some errors, but the measurments and part numbers are there, I've verified enough of what he said about a th400 to 700r4 swap for myself that it's not all bad.

[N2TRUX]

Try www.bowtieoverdrives.com as another good source of information and parts for this swap.

[colt45-2007]

Well I've got good news, we pulled the tranny out of the 83 and it is infact a long tail so that was great to find out.... I also remembered that I had an intake that would fit that 350, its off of my old 305 that I took out of my 88 so I'm trading him the intake for his turbo 350 and I'm going to put it in my dads 81 scottsdale thats been sitting in the yard for a year with no tranny, but anyway we are going to put the 700r4 in sumtime this week and remount the crossmember and make sure everything lines up and then this weekend prolly try and stick the motor in....... I've checked out all the links that you guys have posted and printed them out so I think we can get everything done without any problems, Thank You guys very much for all the help, if we run into trouble I'll hit yall back up for some help lol, but seriously thanks again

[MoFaster]