well i bought an 1985 Iroc-Z with a 400 sbc, Turbo 350 but no title, so i was thinking of swapping the engine into my 89 RS. Is this a good move, or is the 350 a better investment, it's going to be a daily driver only but with some kick in it to keep the ricers at bay. My only concern is my t-5, can it support its power and is the swap even worth it, i have a 305 in it right now? Thank you

 

do you know what your rear end ratio is?

 

its all in what your wanting. 400's are known for their torque. But honestly, if your going to keep this your DD, keep with the 350

 

Just FYI the 400 small block is an externally balanced engine so the flywheel and harmonic balancer have to be for a 400,you can't use the flywheel off the 305 or a 350 with that engine.
Other than that it should be a plug & play,just get the right flywheel and harmonic balancer.

 

My built 400 makes over 500hp and 500 ft lbs, it is internally balanced now but it is a very extensive build.

 

T-5 was not offered with the 350 because it could not handle the torque. Compaired to the 350 the 400 is a torque monster. the 400/350 combo can be a good match if the 350 has been beefed up.Many of the SB 400 came with TH400 from the factory.

 

I'd really prefer to keep the car a manual transmission cause its a whole lot more fun and for that little extra fuel mileage. What about a t-56 swap or maybe rebuilding the t-5? Also has anyone heard of a 400 sbc with a tpi unit. I have TBI on the 305 right now and carb on the 400 and a 400 TBI doesnt interest me AT ALL, what would you guys do?

 

i think i read somewhere its the design of the t-5 that makes it weak. not the gears. but dont quote me on that. i think your best bet would be the t-56 swap.

 

i like the 400 sbc but people tell me they have really thin cylinder walls. so they can do damage if they happen to overheat. just a heads up.

 

I have heard that as well, so if you are interested, you can do like what I am doing and using the 400 pistons and crank to make a wicked 383 stroker witha 350 4 bolt main block. just a suggestion. I know some here will pont out you could buy one for less headachs that cost about 5 grand ( and it do look sweet), but something about the " ya I built it myself" thing I kinda like.lol.