>>>*Lots of information in this post, if I may, here are a few clarifications:

You can't bolt the 20R head on a late 22R short deck block without milling the bejeebus out of it. (Chain won't fit)..We won't do it, it seriously weakens the casting, suddenly head gaskets become "MY" head gaskets again....

So this combination is most popular using the 20R head with the early 22R tall deck block.

On compression, there is no real difference from using a stock 22R early head, combustion chambers are roughly the same, 81-83cc or so.. So they won't ping unless something else is wrong.

Now remember that the 20R head has tiny round ports and smaller valves. *Still, I hear the often repeated claim that it will outflow the 22R head.

K...It doesn't....*Bit like tying a rope around a horse's neck to make him run faster...But I keep hearing that, along with claims of 200+ horsepower to the rear wheels...*Bout the same my 11.96 second 1/4 mile Corvette made back in the good old days..

What it DOES do is run differently. The small port, (now we are assuming no mods here but there are folks out there that are magic with a die grinder..)

*Anyways..the small port develops velocity sooner, the driver feels that. Nice snappy response at low end, always a fun feel with a daily driver..Then: The 22R head has a Vortex, or swirl ledge under the intake valve, in the port. That works well to give nice throttle response, but kinda gets smack in the way when one wants to twist the dickens out of the rpm band.

It simply acts as a wall at higher RPM, so the tiny little 20R port gives nice low end response and will actually wind higher.

So: Put some bigger valves in the 20R head, open the intake ports into a nice tunnel shape (flatten and widen the floor, *yep, gotta fix the intake, too....Don't get carried away, sensitive...) Bit of short side radius work, little nick in the intake runner wall tricks a couple of CFM in there..there is a tiny dead air spot that this helps, All this does is expose more fuel droplets that fall out of suspension to the airstream, remember the engine runs on fuel, not air, and air is easy to move. Fuel can get problematic quickly, which is why I quit paying attention to flow benches and airflow numbers years ago..

Nice for comparisons, I use results on the track for that..still, a flow bench can find those dead air spots, and that is an asset.

*K..I am nuts, but I have a LOT of trophies on my walls...and 43 years to back it all up..*LOL**..so at MY age, even if I am wrong, I get to be right..

Now the 20R head will not only offer that sweet early rpm throttle response, but it will also make power equal to the 22R head, or close, perhaps better if the work is right. AND nice top end, too.

Sweet...

Compression DOES NOT CHANGE from what the 22R head/22R block delivers, you can write that down and take bets on it...

The engine just runs differently, and properly set up, is fun....Hope this helps...*EB