Swap th350,th400,700r4

[VinceGMC]

I have a 87 350 rebuilt out of an Iroc and would like to know some differences between the 3 trannies listed above and what would be opinions on which tranny to use in the swap into a 62 SWB. The engine will be carb’d and no EFI.And if I went with the 700r4,what years would be the best,looking to keep electronics and computers to a minumum.

[zenish]

a turbo 400 is very stong and takes a lot of power just to turn it.not a good choise for a stock 350.turbo 350s and 700r4 are simuler in stength and can be built to last.the 700r4 has an ultra low first gear plus overdrive.im not sure if a 700r4 will fit with your frame.the best 700r4s are from 1987-90 but the earlier ones can be updated to 1987 strength.after 1990 theres no hookup for the speedometer cable.

[bowtieguy61]

the 87 350 is externaly balanced so you need a special flexplate that has the weight on the flywheel for the motor, yet has the bolt pattern for the 350 and 400 converter. summit racing has them. you could try elongating the holes in the flexplate on the motor, but id just a new one, they are only $80. the 700r4 uses the flexplate you have on the motor. they make kits to control the 700r4 without a computer. go for the newest 700 you can get, preferably 87 and on. they made improvements in the later years.

[bowtieguy61]

the 400 is the most durable, followed by the 350. but in a relatively stock motor the 700r4 is up to the task and how nice do you think it is to have overdrive, and a 3.08 1st gear!

[stsalvage]

well i have a 1968 3 door suburban and it has a 400 in it with a 350 i'm having to pull the 350 cus it was built wrong and along the way pulling the 400 and droping the 700R4 in for value and if gas prices shoot up again i know i have the over drive in the most part some people build there hot rods to keep and cruze but look at the big point if you ever had to sell it what would you want from a guy that is looking for a truck car or suburban to have in it for the money that your willing to pay thay had a study on people that. most that own old cars we tend to hold on to them for 10 years max in 10 years if your lucky you might find a factrory 396 with a th400 and the update would be a gear vender or a built 700R4 with all them up dates you have a pretty nice peace of cash cus where not getting any younger and crap happens to us old people so if you where looking for a truck or a car what options are you looking for and willing to pay throw the roof for

[kwkenuf]

Huh?,,,, What?

[62ChevyStep]

I am running a 350/700r4 in my SWB 62'.

Had a th350 with a 10 bolt 3.08 before, but I love the 12 bolt 3.73/350/700r4 combo I have now. Cruises 70MPH @ 2015RPM, but will get it off the line with the low 1st and 2nd gears. Can't wait till the 383 goes in.

My 700r4 is out of a 89' suburban, I used the TCI lockup convertor wiring kit. had to have the drive shaft shortened a little but was well worth it all.

[VinceGMC]

Thanks for the info guys.Just trying to determine exactly what i need to swap this drivetrain over.
here is a little info on the 87 iroc engine that is going inside the truck...not really stock.
it has world sportman II heads, TRW forged pistons, comp cam 08-423-8 roller cam.Had to put new comp cam springs to match the cam and they have been fully shimmed and seat pressures have been checked.1.5 ratio roller rockers and lifters.Trying to decide on which intake and carb to run.I have a nice street avenger carb that needs rebuilding so i may use it.Should all be nice once installed.
Our rear is the dana 4.11.on the little 6 cyl 3 speed,about 60 mph and she is wound all the way out...lol

[ed70]

i was running a 700r4/350 set up but i blew the puke out the tranny so now im going 350/350 set up... loved the over drive and the first gear of the 700r4... i am planning on rebuilding it and putting it right back in... this is a temp trans... dont get the wrong idea about it either from me they are really reliable trans i ran it in to the dirt and so did the last three owners... so i believe it has a good life span.

[Fred T]

I would go with the 700R4. Look at www.bowtieoverdrives.com for info on the tranny and install. Properly built, it will hold up pulling heavy trailers behind a 454. The early models had some problems, but these are corrected with the right parts.