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Topic: chilton manual#52500 page3-35
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driftindatsun
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Joined: 01 December 2003
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bullet Topic: chilton manual#52500 page3-35
    Posted: 24 December 2003 at 2:12pm
claims that the 70-73 l16,l18 timing chain has 42 pins,while the 74-80 l18 and l20b have 44.I went ahead and got another chain,counted the pins on the counter,came home put it on(installed the retainer correctly-machine shop boo-boo) and all is good!notch is in the middle of the oblong hole,that is there now,I knew I needed sleep!     Now on to the int./exh.  Be running by this evening!!Thanks, People!!!          Tom S.
72 521,(2)69 521(2),66 520 82 720 4x4,and a few more....
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driftindatsun
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bullet Posted: 24 December 2003 at 2:14pm
Has anyone out here even heard of a 70-73 L18? I was wondering when they were introduced......Tom S.
72 521,(2)69 521(2),66 520 82 720 4x4,and a few more....
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Bleach
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Joined: 04 December 2002
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bullet Posted: 24 December 2003 at 4:24pm

Ya, my Factory service manual for the 1974 truck shows that some of them had an L16 and some an L18. The L18 was the official engine for that year though. Datsunaholic can probably type up a story on the engine transisions during these years!

But, like was said before. The block of the L16 and L18 is the SAME HEIGHT, so the timing chains should be the same. Maybe if you have an odd length timing chain then you need to have different upper and lower sprockets with different number of teeth... just a guess.

Also, the L16, L18 matches the height and parts for all six cylinders. L24, L26, and L28. (not the LD28 deisel) The L20b really is the odd man out. a much taller block and longer stroke. Nice torque for a 4 banger. I wish I had one.

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datsunaholic
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bullet Posted: 24 December 2003 at 5:01pm
The L18 went into production early calendar-year 1973. That was for Datsun 610s which never had the L16 in the US, but there WERE '73 model year 610s. 510 production was ramped down (no '73 Wagons for instance) and the 610 line was ramping up so there was overlap.

The problem is it's nearly impossible to tell what point a '73 Datsun became a '74. The VIN didn't change (both '73s and '74s had "PL620" as the prefix) but there is a cutoff. That cutoff was for SMOG purposes, but Nissan changed out to the L18 by then. In fact, smog was the reason for the L18 as the addition if the EGR and (in California) the smog pump robbed too much power. For 1975 it changed again to the L20B.

There's only ONE place on a 620 that has the MODEL YEAR. That's the EPA Emission label (a sticker) found on the firewall (through '74) or on the underside of the hood ('75-79). Unfortunalely the label is lost the first time you paint the engine compartment, replace the hood, or time fades it. The VIN plate on the doorframe is the manufacture date, NOT the model year. A truck built in 9/73 is a 1974 model year.

That being said- for US market ONLY '72.5-'73 MODEL YEAR 620s had L16's. ONLY 1974 model year had L18. '75-'79 had L20B. That doesn't mean the engine wasn't swapped though- my '76 and '79 have L18s and my '74 has a L20B. For trucks through '77, IF you still have the original engine room VIN Dataplate, you can see if you engine is original because the engine Serial # is stamped on the VIN plate under the hood (not the doorframe one). The only one I know of that's 100% original is my mom's '73. The #'s match. She's had it since new, so we'd know anyway.


One last note- while the L18 was only used in the US for one year, it was used into the mid-80s in other markets. The L16 was used up to around 1980 as well.
'64 320
'68 520
'72 521 V6
'74,75,79 620s
'76,78 4X4
'76 KC
'72 510 Wgn
'78 B210
'78,81 510 Wgn
2X '78 510 Coupes
'83 720 KC

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