Hybrid 2xR Late Block Build

This will be an on-going thread as I put this together...
I've been planning on a new engine for some time, as the bottom end of the original 22R in the sleigh is still OE with about 300,000 miles, and the nicely modded 20R head has close to 200,000 miles of very hard use - some would say abuse, and that has been with a stage 2 cam, then a stage 3 cam, then a Comp 280, and now back to another stage 3, so it has... "issues". The valves have now sunk so far into the head with the 6,000 RPM runs and stronger Erson springs that I had to clearance the rockers so they wouldn't hit the light weight Erson valve retainers, but they still do, so sounds like the valves are out of adjustment, the valve cover mating surface is warped, the head surface is so eroded that it barely seals a head gasket...
Here's some of the damage the poor head has incurred
Yes, it is warped on the top - that's the surface the valve cover seals against, between 2&3: [You must be registered and logged in to see this image.]

Broken rocker due to failed cam lobe, I think from loss of oil during hard cornering - time for the "Gary M rocker mod": [You must be registered and logged in to see this image.]

Rocker bounced into the valve cover, leaving this hole: [You must be registered and logged in to see this image.]

I did drive it home - about 75 miles on three cyls and had it on the road the next day, and have put probably a good 10,000 on it since then, including a "Cruise to the Coast" and to PSTOF.

Here's that head when "new": [You must be registered and logged in to see this image.]

Exhaust port: [You must be registered and logged in to see this image.]

Stock exhaust: [You must be registered and logged in to see this image.]

My exhaust: [You must be registered and logged in to see this image.]

Intake port: [You must be registered and logged in to see this image.]

SI stainless valves, bronze guides: [You must be registered and logged in to see this image.]

After much work and studying, I've learned that I need even bigger valves, much more porting, and more compression. The oversize SI stainless undercut stem 20R valves and "mild" porting were great for building decent power from off idle to over 5,500 RPM with a stage 2 cam in a DD getting almost 29 MPG freeway in a 2800 lb wagon with an automatic, but runs out of power at around 5,800 RPM with the stage 3.
For those of you who don't know why 20R heads are better, they have very straight intake ports compared to the 22R ports that have a twist to them which is a compromise between a strong, torquey bottom end, and a swirled higher end that runs out way too soon. I love my very modified 20R head, but...
In all of my studying and experimenting with the 2xR engines, I have found a number of interesting facts:
The early 22R pistons weigh over 500g each, but the late 22R pistons are about 400g each.
The 20/early 22R rods weigh 35g less each than late rods (yes, they are different - don't mix them up).
All crankshafts are the same.
The 20R and early 22R combustion chambers are "open chambers", the late 22R heads are closed chamber. This means that the late heads have a "quench area" (actually two). This is where the pistons come up close to a machined flat portion of the head, and squeezes the combustion gasses into the much smaller combustion chamber, which leads to a better burn.
The conclusion I have come to is that I need to build a late bottom end. This will save almost one pound in piston weight, and using early rods, the rotating assembly will be 140g lighter than a factory late bottom end, minus what is removed when I polish the rods, have the crank lightened, knife edged, polished...
I also need to find a way to make a 20R head work on a late block, and change the heads into closed chambers. This requires milling about .160" off of the head, and welding material into the chambers. I'm looking far a streetable (I'll make it a DD - most say I'm nuts) 2xR hybrid that puts out a solid, legitimate 175 crank HP, runs to 6,500, and pulls at least 26 MPG in the wagon on the open freeway.
For starters, I figured I need to do a mockup head so I'm not wasting a good head should this not work. So I'm working with my machinist on this concept, and to be able to see closer what is going on, I took the original junk head off of the (ex) wife's '79 Celica, and got it ready:

According to LC Engineering, 20/early 22R heads measure 3.290", but this "virgin" measured [You must be registered and logged in to see this image.]

Here it is on the head stands, marked and ready: [You must be registered and logged in to see this image.]

And here it is, half ready (punny) to go to the machinist: [You must be registered and logged in to see this image.]

Here's where a .155" cut will be: [You must be registered and logged in to see this image.]

suscribed to this thanks for bring alot of knowledge on 22r's

Next step completed...
The head back from the machinist, has been milled to 3.139, leaving .009 to equal a virgin late 22R head.

Unmilled - at 3.285 [You must be registered and logged in to see this image.]

Milled [You must be registered and logged in to see this image.]

Setup to cc - yes, watching NASCAR [You must be registered and logged in to see this image.]

cc'ing late head... [You must be registered and logged in to see this image.]

came out to 58.3cc [You must be registered and logged in to see this image.]

The early head came out at 59.3cc [You must be registered and logged in to see this image.]

So what this is saying is that if you are using a 20R head w/o changing valves, milling 0.130" off will give you an increase in compression, but I'm not sure how much, as I'd need to take the last .009" off of it to figure final compression.
If you are using larger valves, and I'd certainly hope so, depending on how deep your machinist sets them, milling 0.120 is probably enough. This means that the timing chain won't quite fit... The deck of the block will need to be milled the other .010", and then probably a couple thou taken off of the pistons to keep them at or under deck height. You can get down to .030", and the gasket is .040" anyway, so the (flat top) piston can actually stand up .010".
The next issue becomes valve to piston clearance, depending on your valve size and cam choice. I'm planning on 48mm intakes, and the LC Engineering set comes with 40mm exhaust valves and all of the seats to upgrade the 20R head, but that makes the exhaust valves 84% as big ias the intakes, which is overkill. IMO, 38mm exhaust is fine, as that is still 79%. Recommendations are 70-80%, and they can be on the smaller side as compression increases.
So my next issue is how much can I deck the block and keep the pistons at the deck height. Then again, having the top ring land shorter decreases the "crevice volume" - the space around the ring land that stores air/fuel mixture, which doesn't burn, leads to washing the cyl walls of oil and contaminating the crankcase. I'm heading back to the machinist to see how much he thinks he can mill a piston top, as I cut a late piston in half to inspect - pics to follow.
I'm working on a couple other pieces of this puzzle, and will post them up as I sort them out. I also need to check what a factory piston to deck clearance is and is supposed to be. I did measure the piston dish and valve reliefs -

valve reliefs are 2cc [You must be registered and logged in to see this image.]

late piston dish [You must be registered and logged in to see this image.]

I spilled two drops - the dish is actually 7.5cc [You must be registered and logged in to see this image.]

So now I have all of the numbers to figure the compression ratio, and am almost ready to squeeze the trigger on putting this thing together for real!

More to follow...

Okay, I'm finally getting my new engine going. The old 2xR hybrid is toast, and the current $40 20R is burning more than a qt of oil per tank of gas.

I've been studying compression ratio info considerably, and came to the conclusion that with an aluminum head, "quench" pistons at .035"-.040" clearance, and at least 220 intake duration at .050", plus polished pistons and combustion chambers... shouldn't have any problems at 10.5:1. Since increased compression is "free" power, I'll take all I can safely, and I think 10.5:1 is about the max for a DD w/o any concerE with Supra AFM and TB, since the motor will definitely need the airflow! The next step will be MegaSquirt. Then I’ll finish a 20R head, milled to run on a late block, running my Holley 390 CFM 4bbl until I mimic Teranfirbt (on celica-gts.com) with ITBs on my Cannon sidedraft manifold, which should be the final incarnation.
The reason I’m going with a late motor is for the 100g each lighter pistons that have quench with the late clns about running on pump gas. The old motor was 9.7:1 and ran fine on regular, but had much more power with mid-grade and no noticeable seat of the pants difference with premium.

The plan is for a very tight late LASRE (short deck) 22R, with almost every part hand massaged in one way or another. It’ll initially start as a 22R, then when I get the wiring finished, an ’85 (TCCS) 22Rosed chamber heads, and will still have quench with the milled 20R head. I’m using early rods, polished and shot peened with ARP bolts, which will be over 40g lighter than late rods.
I have yet to check cranks to see if there is any difference between an early 20R crank, late 20R, early 22R or late 22R, but have started working on the late crank that came out of the block that I’m using.

The first head that goes on it will be a well ported 22R head, but unfortunately will have stock valves, as I simply can't afford the extra costs of oversize valves and the machining with the rest of this. I have a few of the late heads laying around, so will work on another one right away to get oversize valves.
The engine will (initially) have a Crane stage 2 cam, as that is the best I have around. An odd fact though is that Crane states that the power range of the stage 2 is 1,800-5,200. Sounds a bit low to me. I'm not sure what the final cam will end up being... The stage 2 cam states "9.5 to 10.75 compression ratio advised," I'll be cc'ing the pistons and head(s) to get to the gnat's ass on CR. The block will be zero decked to ensure .035" piston to head (quench) clearance. As the pistons say on them, they are 1.00mm oversize (.040"), which makes the engine 2417cc - 51cc bigger than stock. The block has been bored, but I need to get some of these pieces finished so I can mock it up to measure piston deck height before it goes back to the machinist for decking, and also for him to shot peen the rods, resize the big ends and install new pin bushings, and balance the crank.
I have a 96 link double row timing chain, but still need to modify an early cover to run on the late block. Yes, I will document it, so anyone else can do it. I also have an "OldMage" double row adjustable cam sprocket as well.

Oh - another advantage of the late motor is narrower rings which create less drag.

The pistons came from John’s Foreign Engines (22re.com). The two lightest ones were 419.8g each, another was 420.0g, and the other was 220.1. Not bad out of the box, but I’ll have them to within .1g when I’m done. Their pins were within .05g, and the rings had no measurable difference. I was going to spray the tops with the heat paint, but the more researching I did seemed to indicate that mirror smooth piston tops were better.

Any questions or comments, shoot away!

Pistons out of the box:
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Starting work:
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Getting there:
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Piston tops finished, after working from 220 grit wetordry up to 2500 grit, then multiple applications of Mother's Aluminum Polish:
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Piston bottoms before:
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Getting there:
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Crankshaft work, not finished:

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Connecting rods
Rough cut:
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Before and almost after:
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