can anyone tell me how to identify an L16-L18-L20

Engine, Transmission and related drivetrain.
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guzzirik
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can anyone tell me how to identify an L16-L18-L20

Post by guzzirik » 22 Dec 2018 17:58

I have a 1970 coupe with an A87 head and 720l on the pass side of the block. just bought it and curious. Thanks

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zKars
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Re: can anyone tell me how to identify an L16-L18-L20

Post by zKars » 22 Dec 2018 19:48

A little flat pad on the block will have a stamp, either L16, L18 or L20. Next to it is another flat spot with engine serial number

datzenmike
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Re: can anyone tell me how to identify an L16-L18-L20

Post by datzenmike » 22 Dec 2018 21:13

Look behind the dip stick handle, left side...

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You may need a wire brush or sand paper and good lighting to see it.
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs

qwik510
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Re: can anyone tell me how to identify an L16-L18-L20

Post by qwik510 » 23 Dec 2018 05:27

guzzirik wrote:
22 Dec 2018 17:58
I have a 1970 coupe with an A87 head and 720l on the pass side of the block. just bought it and curious. Thanks

Is is possible that it says “Z20” not 720?
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datzenmike
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Re: can anyone tell me how to identify an L16-L18-L20

Post by datzenmike » 23 Dec 2018 15:30

The Z20 is stamped in the middle of the block on the left or driver's side of the block under the two exhaust manifold pipes..

Image

Z22 but Z0 similar.

The Z20 is basically an older L20B block with a Z series head on it. The water jacket holes are differently placed but it uses the same L20B crank but 6 inch rods and flattop pistons. Two different Z series heads were used. One is 57cc which combined with the flattops produces an 8.4 compression for the '80-'81 A10 (HL510) The other is around 46cc and produces a 9 to one compression for the 720's Mileage option truck.


Probably miss reading the L and the B on either side of the L20B
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs

guzzirik
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Re: can anyone tell me how to identify an L16-L18-L20

Post by guzzirik » 24 Dec 2018 08:05

That was easy...It's an L18. I don't suppose there is any way to tell which combustion chambers it has short of pulling it. The serial# is 818213 if that helps

datzenmike
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Re: can anyone tell me how to identify an L16-L18-L20

Post by datzenmike » 24 Dec 2018 10:42

Look along the bottom edge of the head just behind the #1 spark plug. With an L18, probably A87 open chamber which gives an 8.4 compression. There are closed chamber A87 heads around but I've looked and can find no mention of them being used on any N Am cars even though people swear they have them from new. It very unlikely Nissan used the closed chamber heads and 9 to 1 compression as this would foul up the emissions certification, besides it would have to be an option. Never happened. It's much easier to believe the closed chamber head (used in Japan) came here on an import engine in the 70s/80s and was swapped in or on more cheaply than a valve job or rebuilding it. This is why there are dual SU intakes and carbs floating around too.

Open chamber U67 or even the W58 will also work and keep the stock compression but have larger port diameters and in some cases larger exhaust valves than the A87.

Anything is possible after almost 50 years. An L16 210 head will also fit and produce 9.4 compression but it's severely restricted in valve and port size. I did put a 510 head on my L20B while the U67 was being milled, back in the 70s. It ran just fine. (better gas?)
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs

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