changing transmisions out what do i need?
 

I have a 400 sbc with a th350 attached to it, and I would like to use my 700r4 with it, what do I need to take the th350 off the 400sbc and then put my 700r4 and stock stall on it?

thanks
Matt

Should bolt right on. You may need to use the flexpalte for the 700R4 but since your car is an 84 it has a 2 piece rear main so it should all be OK. It's been so long since I've owrked on the old stuff but I think all the pre-85 stuff was exactly the same bolt patter wise as long as it was chevy stuff.

the 400sbc should require a ext balanced flywheel. most likely the 400sbc/th350 flywheel is a 165tooth flywheel. i believe youll need a 153T one for the 700r4, BUT that will also have to be ext balanced since your 305 one is neutral balance.

Damn, the cheapest one i found was like 300 bucks, plus it says i need to upgrade clutches.

oops, haha, i meant to say flexplate, not flywheel. there should be a ext balanced flexplate for a 700r4 available at a reasonable price. lemme go look now...

the 400/th350 flexplate MAY work IF a 168 tooth flexplate will clear the case/bellhousing of the 700r4. i know a 168t will not fit in an f body T5/t56 bellhousing. but since gm used the 700r4s on other vehicles, it may be bigger to clear a 168. If it does clear the housing, then you need to see if the convertor bolt pattern(3 bolts) will match up with the 700r4 convertor. If not, then you need to get a new flexplate with External balanced and the proper TQ convertor bolt pattern. 168t versions are available for under 50 bucks or so, but you need to research if a 168t will fit in the 84 700r4.

the attachment bolt holes are the issue -- you need to keep both the front pulley and the flexplate together as they are weighted for a 400 SBC motor -- i do believe the converter will bolt up to your 400 the only thing you will need to check mixing parts like this is -- ( with the converter in place and the thans bolted up to motor you need at least .75 to .100 thousands travel ) back and forth on the converter with the two pieces bolted together -- if the converter cant be pulled back and forth when bolted together don't do it something is wrong -- hope you get what i an saying -- and the holes for converter to flexplate need to match up as well --- jz

I used the stock 168 tooth 400 flexplate when I bolted my 400 up to my 700R4. Everything cleared just fine.

- Justin

the factory 400sbc flexplates are dual pattern for the TC, so you should be able to jsut bolt up the stock 700r4 stuff to it and go

AWSOME! my head aches, about using the th350 are gone :) Thanks alot tim and justin, Do i need gaskets or anything like that??

nope, just get those bolts snugged in good and you wil be ready to rock.

if it was putting a T56 in , ive done that 4 times already, i have some experience and could help.

you will need some parts to install the trans into your third gen... a different driveshaft and crossmember

I think you mis-read....he's got a 700R4 in there now, but he didn't think that it would directly bolt up to a 400sbc.

- Justin

yep i thought it was 700r4 to th350..thanks