1/8" of an inch is ok. Normally they just touch or have a couple of mm.

You mentioned the transmissions turns with the engine. You should be able to turn the converter by hand using fingers or a screwdriver to line up the bolt hole to the flex plate.

If you can't get the converter to turn without turning the engine then the center section on the convertor is probably not lined up with the back of the crankshaft and not entering the crankshaft.

How did you fit the transmission. Did you use the bellhousing bolts to pull it in or did it push up by hand?

It's been a long time since I seen one of these in pieces, and that was in a VL commodore. Memory is fading.

Can you post some photos of the convertor.

I pushed the transmission in by hand it bottomed out on the block pretty easy. My new question is how sure are you about the 1/8" gap between converter and flywheel? i would think that they would touch when the converter was bottomed out on the flywheel so as not to bow the flexplate to the converter  

You've measured everything but the flex plate.  It seems like you either have the wrong flex plate or it's installed incorrectly. 

Position of the starter gear is not confirmation that it's the right one and installed correctly.

I have two flex plates If you would like to compare measurements. 

1/8 inch is about the distance of the spacer / washer.

I would be happy to post some measurements of the flexplate . i will do it tomorrow as I am at home and the car is at my shop. I have the big washer towards the engine and the smaller washer like spacer towards the converter. If I flip the flex plate over the teeth rub the block

Pilot thickness will be important.  Does "big" mean thick or large diameter?  

http://www.carpartsmanual.com/datsun/Z-1969-1978/engine-280z/piston-crankshaft/22

  On 8/1/2020 at 4:42 PM, carcrazyken said:

I pushed the transmission in by hand it bottomed out on the block pretty easy. My new question is how sure are you about the 1/8" gap between converter and flywheel? i would think that they would touch when the converter was bottomed out on the flywheel so as not to bow the flexplate to the converter  

As I said, digging up memories from 33 years ago working in an automatic transmission shop. We use to do an "upgrade" in the commodores. It was a simple heavier spring set in the valve body. You could get these transmissions to churp the tyres going to second gear with a bit of tweaking in the valve body.

Normally the converter will just touch the flex plate or maybe a couple of mm off. 1/8" is getting close to maximum, but it should pull together.

I don't think the 3mm is a problem. The 23mm covertor to flexplate when the transmission is fitted is a problem.

The convertoer has two prongs to drive the oil pump. Can you measure them they should be about 20mm if my memory serves me correctly? 23mm will mean if you get it to bolt up to the flexplate, the pump will disengage.

#22 is on the engine side and #25 is on the converter side

Some thoughts for your puzzle...

Did the flex plate and spacer/adapters come with the transmission, or did you get them separately?

Did the bolts come with the flex plate and spacer/adapters?  How much thread engagement is there for the bolts?  If the flex plate is too toward the engine the bolts should be too long.

I can't find a distinct break point or how the various parts go together or what the difference is but Rockauto seems to indicate that there was a different flex plate before 1975, and after 1982/1983.

Hey Zed,  Ken’s transmission conversion came from my 78 280. I am doing the manual conversion on mine. I provided everything for his conversion directly off of my car. The trans package was a complete set.