4AGE block differences explained (incl. some eyecandy)

[Bean]

Here some info that recently came up again, I condensed it to post it here (click the pictures for bigger versions) - thanks to the involved members for sharing:

In this picture 3 defining things can be seen
[list] 40mm crank, distinguished by the shape of the counterweights (comparison pic will follow)

12point rodbolt nuts common on 20V blocks, early (3rib) 4AGE are regular hex (like the maincap bolts)

the "extra meat" in the block wall @ #3 journal was also only introduced later with the 7rib generation.[/list:u]

so why is this intriguing? this is a changeover block from Toyota (probably from around 1987) as pointed out above it has many features from the newer generations but one important one from the first generations which is the 40mm crank. Also something that can't be seen very clearly is the above block doesn't have oil squirters.

As mentioned before here is a pic of a 42mm crank notice the difference on the counterweights which are equally shaped on the 42mm but not on the 40mm (this is one reason why the 42mm is 1kg heavier).
here's a better picture for comparison
and a nice collection I guess Dan put together as well


next we have a close up of the 10:1 pistons, you'll notice the flat are is higher than the outside edge. The 9.4:1 pistons have this area lower.
here the comparison, thanks Dan and some more specs

next the 7 ribs, clearly seen in this picture
compared to 3ribs

now to add to the confusion my own block, which is a 7rib WITH oilsquirters doesn't have the additional "meat"


Now want might to want to jump to conclusion and say easy 7ribs without squirters had this additional meat and the others don't. As usual it's never so easy as I found this picture:

7ribs no squirters and no meat - this particular block is a late model MR2 1987-1989

I also came across this picture from Ben Willson back in 2007
20V left and 16V right... now I'm not a 20V expert but I know they use different oilpan patterns and there's supposed to be a slight difference in the openings on top where the oil drains back from the head too...


Connecting rods - I also dug up these pictures from the internet showing the different connecting rods used in the 4AGE series.




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