Z20 and L20B Interchangibility

[610racecar]

I have the opportunity to get a Z20 out of a 1980 510 for my 1973 610 race car. The 610 currently has a L20B with a 5 speed. The 1980 510 parts car has a Z20 with an automatic tranny. Is there any difference between the blocks for auto and manual trannies, or will either tranny bolt right up to the Z20?

 

Marc in Indy

[parrot45]

I have the opportunity to get a Z20 out of a 1980 510 for my 1973 610 race car. The 610 currently has a L20B with a 5 speed. The 1980 510 parts car has a Z20 with an automatic tranny. Is there any difference between the blocks for auto and manual trannies, or will either tranny bolt right up to the Z20?

 

Marc in Indy

 

 

there shouldnt be any difference between the blocks fitting a auto or manual, but im im not sure if a l series tranny would bolt to a z20, and vise versa

[zerow]

You will need a Z20 bell housing - The L-Series bell housing has a different engine-to-transmission angle (The L-Series engine tilts and the transmission stays level). If you use the L-Series bell housing with the Z20 engine, the transmission will tilt the wrong way.

[datzenmike]

First, if swapping the Z20 into your dime you will also need to keep and use the brackets bolted between the block and the rubber idolater mounts on the frame. This will keep the motor properly oriented in the bay.

 

 

The Z series motors sit almost vertical in the engine bay while the L series are tilted 12 degrees over to the passenger side. The vertical shifter in your car now would have to rotate 12 degrees over toward the drivers seat if you try to bolt to an Z series motor. Also the trans mission rubber mount would need a wedge shape added to support it if leaning. This can all be avoided by getting the front case from a Z series transmission and swapping onto the transmission you have now. This will have the proper rotation of the mounting bolts and keep it in it's original position.

 

This is the tranny front bolt position for bolting to an L series motor. The two bolt holes at the top are the two top ones in the block.

 

This is the bolt position for a Z series motor. Here you can see the bolt holes are located further to the driver's side of crnterline to accommodate the different tilt of the Z compared to the L series motors.

 

 

Z series blocks are essentially the same as the L20B. There are slight changes in the cast in ribs. Very late L20B blocks are the same casting as the Z20. Visually the dip stick holes and engine ID stamps are on opposite sides. The cranks are identical and fully counter weighted. Bore and stroke the same but the Z20 uses two different combinations of piston/rods depending if carb or EFI and both are totally different from the L20B. EFI Z20 use flattop pistons and 6" rods while carb Z20 use dished pistons with longer piston pin heights and shorter rods. Because they use flattop and dished pistons, two different size Z series combustion chamber heads are also used.

 

To avoid having to swap transmission front cases you could just swap the Z20 block in and use the L20B oil pan and pick up, all timing parts forward of the steel block, engine mounts, L head with intake/carb and exhaust. If this was a Z20(s) carb motor the piston dish is slightly smaller than the L20B and the compression would go up slightly. If this is an EFI Z20 motor then it would really go up. (9.9 to 1)

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[610racecar]

[

 

To avoid having to swap transmission front cases you could just swap the Z20 block in and use the L20B oil pan and pick up, all timing parts forward of the steel block, engine mounts, L head with intake/carb and exhaust. If this was a Z20(s) carb motor the piston dish is slightly smaller than the L20B and the compression would go up slightly. If this is an EFI Z20 motor then it would really go up. (9.9 to 1)

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Could I use the Z20 block as described above with the Z20 head and use my L20B intake/header, or are the intake/exhaust ports different?

 

This is great info- THANKS!!!

Marc

[datzenmike]

Yeah they are totally different. The Z is called a cross flow head with intake and exhaust on opposite sides.

[610racecar]

Yeah they are totally different. The Z is called a cross flow head with intake and exhaust on opposite sides.

 

Interesting- the pic I have of the engine is not a crossflow, but instead is like my L20B. Perhaps it already has a L20B head on a Z20 block, or perhaps the whole engine is an L20B. I will contact the seller and see if he can get me a serial number off the block

 

Marc

[sinner720st]

how about a picture of the engine, and there should be a casting in the side that says what motor it is

[datzenmike]

The L series are stamped on the block just below the head and behind the oil dip stick.. The Z would be on the other side below the front intake runner.

[610racecar]

http://community.ratsun.net/gallery/image/3234-datsun-z20-engine/

 

how about a picture of the engine, and there should be a casting in the side that says what motor it is

 

Here is a pic of the motor I am looking to buy. The owner says it is a Z20S, but it obviously is not a crossflow. Needless to say, I am confused. It looks just like my L20B in my 610

 

Marc in Indy

[wayno]

I am unable to access that link Marc. I get an error page???

[datzenmike]

L20B/Z20/Z22 or Z24 block.... no way to tell from the picture but definitely an L head.

 

If an L block the dip stick will be above the starter. Look behind the handle on the dipstick and on the top edge of the block between plug #3 and #4 will be stamped the engine size. If a Z block, look on the top edge of the driver's side of the block half way back.

 

 

L series location...

 

Z series location

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[wayno]

Hi there Datzenmike, if I am unable to find a Z22 short block, am I better off using my Z20S block with all my L accessories or use the L20b block? I have my ported W53 head with 260Z valves at the machine shop now being rebuilt, and I was looking for a Z22, but have had no luck yet.

[610racecar]

Okay, it is definitely a Z20 block. The dipstick is on the driver's side of the block. Since it has the L20B head and manifolds, can I swap on my oil pan/pickup and motor mounts and drop it into my 610, or do I still need to get the front part of a Z20 tranny case as well?

 

Marc in Indy

[IrvinM]

Hello, I am fairly new to Datsuns. I just got a 1975 Datsun 620 pick up and I am looking for parts. Yesterday I found something that looks like a Datsun 510 with the year imprinted 1981. It looks exactly like the one in the picture.

The one I found has a Z20 engine in it. I would like to know if I can use the same carburetor on my truck. My truck has an L20B engine.

[datzenmike]

The Z20 will have a threaded post coming up from the middle of the carb using a wing nut to hold the air filter housing on. The L20B is different and clamps around the throat of the carb. Probably you can make it work if you also use the Z20 air filter. Check that the Z20 carb linkage pulls the same way when turned around and used on the L20B. THAT I'm not sure of.

[datsunaholic]

Z20 carbs pull the same way.  It just uses a longer cable to reach across the engine bay.  My '74 620 had a Z22 carb on it when I got it.  I used a 720 air filter for a while, then went with a Weber.

[Gery]

I came across a 1980 200sx with a z20 and 5 speed transmission.  Could the entire power train replace the power train in a 620 kc (currently automatic)?  If so, how difficult a swap is it and what benefits (besides getting a 5 speed tranny, which I would prefer to an automatic) and losses would this involve.  

Also, could I ever hope to pass a California smog test?

[datzenmike]

The Z20E was fuel injection and would be a lot of work to swap into a carb 620. You would still need a 620 clutch and brake pedal to make this work. Check with the DMV but it would have to pass the smog test for a newer year '80 200sx.

 

Advantages are easier faster starting and better idling, better mileage, all this in any weather. Possibly better (only slightly) performance.

 

Not the entire drive train, only the engine and transmission. The H-165 differential is much too weak for a truck.

[Gery]

Thanks, Datzenmike!

You are a veritable wealth of knowledge.

[Stoffregen Motorsports]

15 hours ago, Gery said:

I came across a 1980 200sx with a z20 and 5 speed transmission.  Could the entire power train replace the power train in a 620 kc (currently automatic)?  If so, how difficult a swap is it and what benefits (besides getting a 5 speed tranny, which I would prefer to an automatic) and losses would this involve.  

Also, could I ever hope to pass a California smog test?

As a general rule, when doing an engine swap, or "Engine Change" as the CA BAR calls it, you need to utilize all of the engine components from the vehicle that supplied the new engine. This can include fuel system, EVAP system, exhaust system, complete intake tract, emissions electronics, air pump, etc. It can go as far as requiring the original fuel tank if it has breathers and EVAP parts on the tank or in the filler neck.

 

Check with https://www.bar.ca.gov/Consumer/Referee/Referee_Centers.html for more info. You can call them, but you leave your info and the questions you have and a referee inspector will call you back.

 

It is not a simple procedure, so if you're going to go through the hassle of having an engine swap certified, you'd be better off choosing a more worthy engine, like a KA24E out of a D21 Hardbody. For roughly the same work, you'll have about 50 more HP and more modern electronics.