Here is a link for ya, with pics, explaining the differences.
http://www.babcox.com/editorial/ar/ar119838.htma little more info:
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Measurements for ref: (I know, im answering my own questions....)
Proper Deck Heights – Blocks & Heads
Whenever you go through an engine or cylinder head re-build, there will be some amount of "re-surfacing" that has to be performed to either the block or the head. Most frequently, it's the cylinder head. This is also known as "decking."
For machining purposes, deck height on an engine block is the measured distance between the "Center Line of the Main Journal" to the "Deck Surface". This can only be performed with the engine block disassembled and the crankshaft removed. Toyota factory heights would be:
Early 20R Blocks 75-80 9.120"
Early 22R Blocks 81-84 9.120"
Late 22RE Blocks 85-95 8.930"
For easy identification purposes, with the engine still assembled, deck height on an engine block is the measured distance between the "Oil Pan Rail" (bottom of the engine block) to the "Deck Surface" (top of the engine block). Toyota 20R, 22R and 22RE engine blocks have these factory deck heights:
Early 20R Blocks 75-80 11.280"
Early 22R Blocks 81-84 11.280"
Late 22RE Blocks 85-95 11.090"
Deck height on a cylinder head is the distance between the bottom of the "Camshaft Journal" to the "Surface of the Cylinder Head" itself. Toyota 20R, 22R and 22RE cylinder heads have these factory deck heights:
Early 20r/22R Heads 75-84 3.290"
Late 22R/22RE Heads 85-95 3.130"
These numbers are especially important if you have purchased a pre-owned engine and have no idea what, if any, modifications were made prior. In other words, it's a starting point in establishing how much re-surfacing has already been performed to the head or block. Example: If you have a late 22RE cylinder head that has a measured deck height of 3.110", then it is probably safe to say that the head has been "decked" approximately 0.020".
c/o LC Engineering
From personal experiance
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Did you know that 20 r motors and 22r motors all use the same crank and conecting rods from 79 through 95?
Early 20R Blocks 75-80 9.120"
Early 22R Blocks 81-84 9.120"
Another weird fact is that even though these blocks had the same deck height the 20r uses flat top pistons and the early (td)22r uses dome pistons due to a head change.
The ID difference between the two being a 20R has round intake ports in the head and the 22R has square
Some 20r info:
1975 1982 20R Cylinder Head
Round Intake Port / Round Exhaust Port
80 / 81cc Chamber
In. Valve Dia. 43mm / Ex. Valve Dia. 35mm
More info I found:
The short deck has a slightly lower block than the tall deck. (duh)
The short deck uses a 2 less links in the timing chain. 96 vs 98 links
I have been told that the 96 link single row chain can be upgraded to a double row by using a modified early 22R timing cover, oil pump, drive spline.
The 20R exhaust manifold had air injection that mounted on the manifold top and no oxygen sensor mount.
The 22R does not and some do and dont have an oxygen sensor mount.
The 20R exhuast manifold outlet has a single outlet into the exhuast pipe.
The 22R exhaust manifold had dual outlet.
The 20R exhaust manifold usually had 1 lower center mount stud.
The 22R exhaust manifold usually had 2 lower center mount studs.
Some early 22R exhaust manifolds had single lower center stud hole.
Some 22R exhaust manifolds had both configs of holes and had 3 holes.
Aftermarket exhuast manifolds usually fit all 20R/21R/22R by having all possible holes.
(
http://ourworld.compuserve.com/homep...pho/eng20R.htm)
On some of that I'm not so sure, I think the 22R also had the air injection. Plus, after 20 years, who knows what has gotten swapped out.
Here are a couple pics to help ya identfy what ya got.
20r ehaust port shape
22r exhaust port shape
