Re: Installing turbo 400 trans to ZZ4 engine.
Uhmmmm, you've lost me
None of the demensions you're giving match anything I'm familiar with from GM ...
GM converters have three patterns - 9.75", 10.75" and 11.50".
Flexplate patterns vary by year of engine/type of rear main seal and ring-gear tooth count. Some are dual-pattern, others are single pattern.
IIRC the ZZ series engines are delivered with the small (153 tooth) 1-piece seal style flexplate. These will have a 10.75" torque converter bolt pattern on them.
Only the earlier (2-piece seal) 153 flexplates, used on the pre-86 engines, have the dual 9.75 and 10.75" patterns for torque converters.
Soooo - you need a 10.75" torque converter pattern to match the furnished flexplate pattern.
If I'm missing something let me know ...
Other V8 things - some of which float
Other V6 things - none of which float
Oh yeah, and 1 "Straight-Six" ...
If a man says something in the garage - and his wife can't hear him - is he still wrong !!!