G52 2.0L Head On A G54B 2.6L

[camoit]

From the Archives

OK everyone. Here is what I found out by taking detailed looks and some measurements. In regards to the intake and exhaust ports. They are the same size. Same bolt pattern. The only thing I found is on the 2.0L NON-Jet head there is a small hole that connects the exhaust ports together using a common rail in the head. This is for the fresh air injection into the exhaust. You will need to plug them.. As for the intake ports the 2.0 head is missing the cute little grove that connects the jet valves to the intake. The only BIG change is the depth of the combustion chamber and the exhaust valve is dished this gives it just a little more CC. This along with the extra depth of the combustion chamber makes it a 2.6. They might have a different rods but I'm not going into the block.

So the answer for the early First Gen is YES get a 2.0L head and stick it on your 2.6L but the fuel pump DOES NOT FIT. You will need a 2.0L fuel pump.

The change over happened in 1983. Then there are some major changes. On the intake manifold the 2.6L has a tube for the air jet system. Just take a look and see if the port is blocked by a flat spot on the head and the gasket. Last is the fuel pump hole. It is just slightly different. Studs not bolts. I will update this page as I do the swap.

NOTE:
Make sure you use thicker gaskets. This will keep the compression the same. If necessary use shims. Take your head to a machine shop have them check to see how thick it is. If the head has been surfaced or planed you must a thicker head gasket. If you don't you can have timing chain problems. Then the chain is to long and the cam timing is retarded along with the adjuster out of speck. If the gasket is to thick then the cam timing is advanced, this is better then retarded. If unsure what to do go with advanced. You can correct this with ignition timing...... Use a 0.073 thickness head gasket if you have had any machine work to the head or block or the parts are not standard, so you will need the thicker gaskets.

Tech Note
first gen Head 54.50 CC
2.0L first gen Head 55.90 CC
Measured head thickness. Head gasket surface to valve cover surface.
NEW: 3.543 - 3.548 inch's
Minimum 3.523 inch's. Anything less your head is junk.



NOTE THE AIR INJECTION HOLES. YOU WILL NEED TO PLUG THEM OR YOU WILL HAVE AN EXHAUST LEEK..



VALVES ARE THE SAME



AIR INJECTION PORT

[camoit]

Plug this hole.



Ok here is what I have found out about my head swap. The holes that are shown above will cause you a problem. IF, the only head gasket available is the narrow one. It’s ½ inch smaller.



If you only can get the narrow one this will leave the holes open for a big exhaust leek between the head and block. The passage that the holes are open to is for air injection into the exhaust system. You might be able to find the proper head gasket that will go all the way to the edge of the head. This will save you time and money. The air injection on early 2.0 car engines the air is sent into the timing chain cover just above the water pump on the left side of the block. On the 2.6L this hole is plugged, as seen below.



The air then is routed up to the head then flows through the passage to the hole and into the exhaust system. Newer engines just inject the air directly into the manifold and not through the head. So here is how I fixed the problem. There are several ways to fix the problem. One is it to weld the holes closed. You can have them welded at a shop. But for my application I went another way. I didn’t want to spend the money to weld it. I now have $1850 bucks into the project of getting this thing up and running again in a truck that is worth $600 bucks.
On with for the repair. How to fix the problem of the holes in the heads. To fill the holes I used some tapered drive pins.



I cut them down so there would be less to remove inside the exhaust port with the die grinder later. I then cut down the fat end and checked the fit. I wanted them stick out of the head just a little after setting then in with a hammer. I want them to protrude above the head surface somewhere around .080 of an inch.



With them sticking out of the head just slightly it makes them self-drive into the hole after the head is installed, locking them in place by the block.



There is no way they can fall out or come loose. I ground the pins down inside the port after tapping them into place.



After setting the head and torque down the studs I could check to see if my idea had worked. If all goes well then they should drive into the exhaust port just a few thousands. Here is what it looks like after installation. Then just grind off the last bit and there plugged.



I picked up some ARP 20,000 Psi head studs. They cause some small problems of there own. The valve cover won’t seat all the way down. This is due to the PCV oil baffle on the cover. All I did was bend the side tabs outward. They hit the shoulder of the nut it self. This causes a leak at the rear of the engine. The engine I have is a California engine. All I know is that it is a 2.0L that came from a car not a truck.



Now to finish up the swap I used the old fuel pump from the 2.6L just to plug the hole. I removed the pin, arm and spring, Now she runs just fine again.

[robertson5347]

Hello, I'm back since the weather has warmed up so I can get back to work on my truck. This gives the cc info. for a 1st. gen. head. What is the cc. for the 2nd generation 2.6 head? Will a 1st. gen. mechanical lifter head work in place of 2 gen. hydraulic lifter head? Are they any markings on the heads which determines where they came from or what engine they fit?

[pennyman1]

Yes they will interchange if you use the complete head assembly - cam, rockers, etc. The main difference between the 2 heads are the rockers, valves and keepers - the mech head uses 1 length of valves and keepers, and the hydraulic head uses a different length valve and different style keepers. They can be interchanged between heads if you swap all valves, rockers, and keepers. The replacement heads work for both types of valvetrains for this reason.

[camoit]

The only thing that I can see the first gen blocks don't have an oil passage drilled for oil to the cam. It was a splash and spray system. No bearings. I don't think they can interchange unless you fed the oil system some how.

[pennyman1]

There is an oil passage - its just routed differently. Go to http://b2600turbo.com/index.html for all the details on each type of head for a 2.6 - the 2.0 g52b are the same as the stock early 2.6 heads

[jw81408]

hey guys..on a little different angle.. if I buy a fuel injected 94 2.0 to put in my 87 mm, can I simply just change the intake to my carb intake??

[pennyman1]

what is the 2.0 head off of - if its a car head it won't work without major changes. There were no 94 2.0 motors in the trucks that I am aware of.

[Malaking_TT]

What will the CR be after swapping the head? I'm new to Mitsubishi's but have a lot of Toyota experience and a common myth in the Toyota world is a 20R head on a 22R will increase the CR but in reality it's nearly the same because a 20R has an 8.4:1 CR while a 22R had 9.0:1 The combustion chambers were almost the same size.

[pennyman1]

this swap raises the compression ratio as the combustion chambers are smaller on the 2.0 head vs the 2.6. about a 1/2 to 3/4 of a point.

[robertson5347]

This is from a previous post I had about 1982 2.0 head vs. a 88 2.6 head. These measurements are close. I used a space saver shim and supposely brought down the compression ratio to 9.8 to 1. Anyhow it seems to run better.

I found another issue, When I went to put a new head gasket on the probably 82 head. I found a considerable difference in the diameter which was about 0.5" smaller (3.25") than the original head (3.6") that I had not noticed before. When I CC'd the head, the replacement head was 60cc's with a compression ratio figured at around 10:1. The original head was cc'd at 74 cc's with a compression ratio of about 8.6:1. Would this high compression ratio be the cause of predetonation and why it looses power above 50 mph? Any suggestions? Do I need to dump the high compression head in favor of a same year stock head?

[pennyman1]

the issue you have is the fact that the 2.0 head motor had dished pistons vs the 88 2.6 with flat top pistons. the 2 together push the compression ratio over 10:1 without the shim. If you want to lower the compression ratio back down close to stock, there are companies that make thicker head gaskets to any thickness you want. Or you can run alcohol injection to fix the detonation issue. where are you setting the timing to, and is the advance working properly?

[abeemanator]

So I have a 2.6 and it has mechanical rocker arms on it but the "new style" valve cover sits too low and the rockers hit the valve cover... not my doing but the previous owners.. so what valve cover is the right one to use? Is this a 2.6 head or not? It has mechanical rocker arms along with jet valves

[camoit]

This is a G52 2.0L Head On A G54B 2.6L
I used the 2.6 valve cover. I went through with as much detail as I could in the post at the top.
The post is using the new 2.0 head on an early first gen. The early first gens have the large came bore hole in the head and valve cover. Later models had hydraulic adjusters and the small cam bore made it appearance. The G52 2.0L is a large bore cam hole with the distributer in the head.

[pennyman1]

if the rockers are hitting, either grind the ribs down or find a different valve cover from an older motor, like a k car or caravan with a 2.6.

[noahwins]

I drove a 2.6 for the first time up from LA to SF and fell in love with the torque and propeller plane sound of the 2.6 while cruising down the freeway in 3rd in the A904 Torqueflite. First time driving an Astron and it won't be the last.

B2600turbo.com has rotted away with time but here is an archive. Click on the various years and blue dots on the calendar to pull up snapshots of the site. Not all of the links work but you can piece it together with a little hunting through the archives.

https://web.archive.org/web/20130515...b2600turbo.com