The overbore wont be a problem. These blocks can be punched out to 94mm with no problems.
What pistons are you running?
How much did you take off the head?
What head gasket are you running?
With the right fuel management you can run almost any setup reliably.

 

going to run stock type pistons, havnt had the head machined yet...Ill tell them not to take any more than needed.

Ive had good luck from engnbldr's gaskets, going to run that im sure.

What about arp head studs? Wouldnt that cancel out any worries of blowing a head gasket with the upped compression.

Can you explain the fuel management you mentioned above? Do you mean having the carb tuned perfectly? Thanks for your help

 

First, you cant run stock pistons with a 20r head on a 22r block. The deck height is different.
Also, the 20r head needs to be cut to the same height as a 22r head. I dont remember the exact # but over .150" needs to be removed. Yes its alot, no its not a problem.
ARPs are definately recomended for high horsepower apps. The stock bolts are fine for stock to mild builds.
My preference for the head gasket is MLS, LC makes these. (The block and head must be surfaced specifically for these so be sure to tell your machine shop what gasket you are running.)

 

You can run stock pistons regardless of whether your hybrid will be based on an early format, or a late type. For the 84 and earlier hybrid, the head need only be properly surfaced for flatness, and the gasket type being used, composition, or MLS. LC does not make the MLS gasket they offer, Cometic does. If you're using an 85 and newer block, the 20r must be milled to 3.775 end thickness, depending on the allowance of the egr port. Cam choice is going to be critical, so do not fall into the trap of buying a cam because you think the numbers look sexy. Do the math. Use the appropriate head bolts for the format you choose, early type are longer, and will show false TQ. figures when used on the late format. On the late hybrid your end compression will be over 10.0 with
+.015 deck height. With the early type you'll need to address the #3 chamber on the intake side as the ring dome has a habit of needing clearancing of about .005. Pay attention if you're going to build one of these, and get the facts straight, you'll see a much better end result. THE MOST IMPORTANT< OVERLOOKED ITEM: If you're cutting a 20r head to use on a late block the dowel pockets will be too shallow, this will allow the head to bottom on the dowels, and not crush the head gasket, you'll see nothing but blown gaskets because of this. You'll need to have the dowel holes properly drilled.

 

Are you planning to port the cylinder head? A stock 20r head wont flow as well as a stock 22r head.

 

20r/22r hybrid

Here's some questions I asked.

what type of 22r block are you using? some older 22r blocks are 0.190 taller.

block info
Engine Block Identification
1975 - 1980 20R Block
Deck Height 11.280"
Stock Bore 88.5mm - 3.484"
Maximum Over Bore 90.0mm - 3.544"

1981 - 1984 22R Block
Deck Height 11.280"
Stock Bore 92.0mm - 3.622"
Maximum Over Bore 93.0mm - 3.662"
Big Bore Forged Piston Kit 94.0mm - 3.701"

1985 - 1995 22R-22RE "Laser Block"
Deck Height 11.090"
Stock Bore 92.0mm - 3.622"
Maximum Over Bore 93.0mm - 3.6662"
Big Bore Forged Piston Kit 94.0mm - 3.701"

Using a 20R Head on an 85-95 22RE Block.lc's technotes
It is possible to run a 20R Head on an 85-95 laser block. In order to keep the cam and crank centerline consistent with an 85-95 head, you must mill the 20R head to a measurement of 3.130 (measured from the bottom of the front cam journal to the deck of the head). Remember to re-machine the oil passage back into the deck surface of the 20R head after milling to retain oil passage to the top of the motor.

 

OOps, your right, I forgot about the early 22r. Im so used to dealing with late blocks.

 

hmm, i didnt know anything about all that. Maybe ill just stick with the 22r head.

 

So is it early or late. An easy way to tell, the early has pop up pistons and the late are basically flat with a small dish and eyebrows cut for valves.

 

so these are the 2 types of stock pistons

81-84 22r


85-95

 

I'm running an 84 block built by LC, and a 20R head also build by LC. We used the studs that LC sells as well as their gaskets. I've got about 25,000 miles on it right now. I eventually fuel injected it via a chevy 4.3 tbi injection unit, and I'm pretty happy now that some tuning has been done to it. If I had to do it over again though I wouldn't bother with the hybrid since a well put together 22re will do just fine, and you dont' have to mess with one off parts or running chevy stuff.

 

Ive been running this setup for a while and have had no problems. I have an 83 22r block with the popup pistons and a 20r head. When i had it rebuilt i used a toyota head gasket and it works great. Also put an LC stage 2 cam in it. Dont think its going to be a hot rod because its still just a 4cyl yota.

 

There's no increase in compression with the 20R head. I've been running a hybrid in my daily driver for about 5 years now. And yes, it's a worthwhile upgrade if you need to do head work anyway. Don't go overboard on the cam or you might not like it so much, and degree the cam to about 1-2* advanced.

 

its an 82 block so its the tall block. Im not expecting hot rod gains, im not even going with bigger valves. Ill install about a 440 lift cam.

 

I don't feel it's worth it if you're not going to touch the head. 20r valves are smaller than 22r. Ran one for a few years with 22r valves, ported with polish chambers and stock 160,000 mile cam. Ran better than stock 22re's with headers. Very slight average increase in compression. Not enough to worry about. 2 to 4 cc's per chamber.

 

why is it that your end hight of 3.775 dose not match with lc's 3.130?

:homer:

 

Because LC does not set the standards for DOA Racing. They do their thing, I do mine. Trail Gear is running my hybrid, this engine uses the measurements I've quoted.

 

Running 22R valves in the 20R head is a bad idea. The 22R valves are shorter by about 1/8" IIRC, so you either have to sink them into the head (lowering compression even more) or your valvetrain geometry is way off.

Tim, so the EGR port is the thinnest part of the deck surface? Over on the exhaust side right? That's new info. Is that the only important part to attempt measurement when figuring out if a head can be milled far enough for a late-model hybrid?

Also Tim, have you ever done the 20RE intake port modification, and if so do you think it's worthwhile?

 

Running 22R valves in the 20R head is a bad idea. The 22R valves are shorter by about 1/8" IIRC, so you either have to sink them into the head (lowering compression even more) or your valvetrain geometry is way off.

As I see it, your adjusting screws will only be down farther. The rocker rests in the same place. True, not what it's designed for, but I'm not sure it's a bad idea.

Now a regrind cam with a smaller base circle alters the resting spot of the rocker. This has more affect on how the rocker contacts the valve versus 22r valves.

Plenty of people doing both with no problems

 

Tim will you explain this alittle better, kind of confused me.

Use the appropriate head bolts for the format you choose, early type are longer, and will show false TQ. figures when used on the late format.

Do you mean, ONLY use 84 and OLDER head bolts for 84 and older blocks, and vice versa for 84 and newer blocks?

Tell me if i have done this hybrid right:

Block will be bored no more than .020 over due to risk of blowing head gaskets with the already upped compression with the hybrid setup.

Head milled JUST ENOUGH to clean and flatten surface. Stock 20r valves and components, with a decent top end cam(this is more of a DD)

Going to use arp head studs, so head gasket issues shouldnt be much of a problem if I do everything right.

I dont care about flow numbers and all that who-raa. I wanted a reliable truck with a bit more punch than stock. By the way it is an 83 22r. Thanks for the help.

 

Block will be bored no more than .020 over due to risk of blowing head gaskets with the already upped compression with the hybrid setup.

I'm sure Tim will get back to you with answers to most of your questions.. He's been building these for years.

I wouldn't sweat .020 over - I've done blown motors at .060 over. LC runs turbo stroker motors at .080 over - at which point not all blocks make the cut.

The less you can cut the cylinders the better.. If you're really worried, you can have them checked out ($$). For a non-blown application, I see no problem..

Tim's the expert!

 

Tim, the cam will have 440 lift, thanks for the tips on the clearances.

About face cutting the exhast valve, i have no clue what that means or accomplishes, the head just went to the machine shop for a valve job, should i call and request that procedure? sorry for all the silly questions, i just want to learn as much as i can, that way i have no excuses for not having a strong motor.

 

Ask the machinist to perform the face cut on the exhaust valve, it WILL help flow. Intake flows in, exhaust flows out. Picture this in your mind and you'll see the intake port has a task quite different from the exhaust port, exhaust has to exit the cylinder opposite of the way intake flow enters, understand? The face cut smoothens this.

 

no.. I had mine bored .40 over and it was running 220 hp strong...