1978 401 in a 1984 J-20,727

MADMAX401

I INSTALLED A 1978 401 IN A 1984 j-20 727 auto, installed flex plate for 401 torque flite trans, bolted the engine to the trans,bolted flexplate to converter, but when you tighten bellhousing bolts engine won't turn over, i loosened bellhousing bolts,engine turns over! what is the problem? MARK :(:

Lifted79CJ7

Sounds like the torque converter isn;t seated correctly. Be very careful, you can kill that tranny if the TC isn't seated right!!! Jack

pyagid

Lifted79CJ7 wrote
Sounds like the torque converter isn;t seated correctly. Be very careful, you can kill that tranny if the TC isn't seated right!!!
Jack

Definatley. Sounds like you need to pull it again and make sure it is seated. SOmetimes they are tricky to get to drop that last 1/2" or so

tufcj

If the 401 had a TH400 auto previously, there may be a very small shim in the crank that centered the GM converter.

Lifted79CJ7

Oh yeah, I forgot about that. My 78 401 was in front of a TH400 and the little piece of metal was a bastard-o to get out, but otherwise the TF won't fit. You also have to remove it if you want to install the bearing to run a manual transmission. Go ahead and bust out the dremel and start grinding that thing out. If it is not that, then it is definitely the Tq Converter not seating correctly. I had both of these problems when swapping in the 401 and TF727 into my CJ7. Jack