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Numbers not matching what engine/carb is this? (Adult Language)


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I recently purchased this 620.... and some shit isn't adding up. Normally, I'd edit out the foul mouthedness but... well... I warned you. All those whom are offended by reading cursing on the internet... do not pass.

 

There... now that's settled, let's get down to business.

 

IMG_1019_zps6ofp6w9b.jpg

 

This little piggy says L18.

 

IMG_1039_zpsvmsszhtz.jpg

 

This little piggy says L20B 606792

 

When in doubt, side with the block.

 

With the obvious swap... my 1974 Service Manual is kinda nullified. Which of course is where the sheer fucking genius of having an online collective of enthusiasts really shows it's stripes. Can anyone tell me what year of car/truck this would have come from in case I need a... well... anything.

 

The purpose of this is to identify the pieces under the hood, and to address anything that you believe to be clearly out of order. A little ribbing of the OP is also welcome.

 

IMG_1040_zpsfg2kiqof.jpg

 

The wires running over the heater hose actually aren't hooked to anything... like many other wires under the hood.... but what I want to know is, WHAT HEAD IS THIS? Is this the right angle to tell? Please provide your input.

 

IMG_1042_zpsteatstzz.jpg

 

Ok... breathe... who the fuck, fuckity, fuck, fuck, fuck puts a wirenut there?!? That's not how this works... that's not how any of this works.... if you have a picture/comment of how to not do this half assed... please share.

 

I know the picture is sufficiently dark not to be clear, but it looks like the brake master has been upgraded. Of course, I could just be retarded.

 

I'll keep posting pics in just a min...

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Didn't want to lose such fine work...

 

IMG_1043_zpsv9p97q1c.jpg

 

Let me direct your attention to center frame. There are two white tubes that look like they should be connected to something coming out of what I assume to be the thermostat housing. Yes/No? Any clue WTF those should connect to?

 

Yes, that is a metal, paper covered, bread twist tie being used for spark plug wire management... fuck my life... that shall be dealt with soon.

 

IMG_1044_zpskqsupd1a.jpg

 

Let's focus on the carb. Can you tell me what it is? Do you know what air filter that is, and where I can get one that's not full of, what appears to be viper semen and cat hair? Someone had a lot more fun in this 620 than I have...

 

IMG_1045_zpsbhh2rllv.jpg

 

Remember the wires I talked about that didn't seem to go anywhere... well... they have a lot of fucking friends. This is actually what started this. My reverse light, driver side, is on all the time. And my brake lights... don't work. As I go through routine trouble shooting I'll fix it, or start a sister thread. Since the lights don't work... it should probably be titled "Who's In My Mouth".

 

Back on topic, I'm assuming this should not be like this. The truck runs though, so I'll try to sort through this shit and find out what goes where. Is there an easy way to tell what transmission is in it, or do I just setup a fuck ton of mirrors at random angles underneath and hope one of them shows me the number on top of the bell housing?

 

Thanks for reading this, and for your input. I'd love to be able to speak eloquently about my Datsun knowledge... but it's blaringly obvious that I have none. I'll get there though.

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The head us a U67. To verify, look along it's bottom edge near where the battery cable bolts to it behind the fuel pump between number 1 and 2 spark plugs.

 

The L20B is almost indistinguishable from the earlier L16/18 so your manual is hardly missing any info. It has a longer stroke, a six bolt flywheel (not 5) and is 2cm (3/4") taller than the L18 that was in it.

 

The white tubes are a temperature controlled vacuum switch used on the L20B to prevent EGR when the engine is not warmed up. This is not a problem, as who ever swapped your engine kept the L18 intake and exhaust which does not have this anyway. So... no worries.

 

Looks like a Weber 32/36 carburetor. They are much different from the stock Hitachi that was on it. So it will be totally different to trouble shoot and adjust.

 

The '74 was the first year to use the 240/260Z car's F4W71B 4 speed. Very tough and reliable as it is a six cylinder strength transmission.

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Hardly anything original anymore with our vehicles.  BTW, that's a typical see through, in line, gas filter available at your local auto store.  That L20 has a little bit more power and came later than L16 or L18 and yes it looks like a 32/36 weber.  Main thing is that it runs and don't worry about things not matching because after 45 years or so very rare to see engines and trannies matching. The wire nut holding the wires together from the ballast resistor to coil is for house wiring, get better ones. How does it run? Do a compression check.  Other than that welcome and good luck!

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Previous Owner re-wiring is usually from lack or money to properly replace what isn't working, lack of common sense electrical knowledge, lack of 620 truck knowledge (how things work) and installing shitty tape player/fog lights/CB radio or any combination of the above, liberally sprinkled with short cuts.

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The head us a U67. To verify, look along it's bottom edge near where the battery cable bolts to it behind the fuel pump between number 1 and 2 spark plugs.

 

The L20B is almost indistinguishable from the earlier L16/18 so your manual is hardly missing any info. It has a longer stroke, a six bolt flywheel (not 5) and is 2cm (3/4") taller than the L18 that was in it.

 

The white tubes are a temperature controlled vacuum switch used on the L20B to prevent EGR when the engine is not warmed up. This is not a problem, as who ever swapped your engine kept the L18 intake and exhaust which does not have this anyway. So... no worries.

 

Looks like a Weber 32/36 carburetor.

 

The '74 was the first year to use the 240/260Z car's F4W71B 4 speed. Very tough and reliable as it is a six cylinder strength transmission.

Thanks buddy. So I can order parts like water pump, alternator, starter, from the original L18 and they'll mate up? I like to have these things on hand. I have a complete engine and trans for my DD sitting on stands in my garage with everything installed... I just like to have shit ready to go, because things break.

 

There's a lot of discussions about those Webers on here, so I'll read through them. It actually came with an extra one in the "crate o' shit" that was in the bed. Along with a bunch of parts I'm sorting through.

 

I'll cap those EGR lines off so nothing crawls in there.

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"A little ribbing of the OP is also welcome"

 

Challenge accepted.

 

It sounds like you're new to the vintage/classic/collector/old car community, otherwise stuff like this wouldn't lead you to expletives. If you are new, then welcome. If you're not, then I apologize for my judgement.

 

There are many ways in which a L20B could have found its way under the hood of your truck, but the only thing that matters to you is finding out which accessories (manifolds, carb, distributor, etc) are on the L20B now. Some changes occurred between the '74 L18 and the later L20B so if the later bolt-ons are present, then you might consider finding '74 correct replacements. The carburetor and intake manifold are the two items I would be concerned with. If the truck is old enough (not sure what your emissions laws are like up there), I would scrap the OEM carb anyway and bolt up a DGV Weber.

 

The exhaust manifold also may be different as some of the cylinder heads had round (less desirable) exhaust ports.

 

These engines really are very simple so with a little research and knuckle busting, and not that may dollars spent, you should have a good little runner in no time.

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Hardly anything original anymore with our vehicles.  BTW, that's a typical see through, in line, gas filter available at your local auto store.  That L20 has a little bit more power and came later than L16 or L18 and yes it looks like a 32/36 weber.  Main thing is that it runs and don't worry about things not matching because after 45 years or so very rare to see engines and trannies matching. The wire nut holding the wires together from the ballast resistor to coil is for house wiring, get better ones. How does it run? Do a compression check.  Other than that welcome and good luck!

Compression will be checked once I tune it up. Honestly though, it runs well. I don't think I cold take a school bus from a stoplight, but if I wanted a race car... I'd drive something else. I just wanted to know what plugs/wires/cap and stuff to put in there.

 

My worst wiring nightmare experience was swapping harnesses to work to run a Duramax Diesel in a Ford F-350 that had started with the 6.0 turbo diesel.... so these are just a nuisance. I pulled out my mil spec connector kits, then realized... I just need to tape it. I don't race anymore, so why do a bunch of shit that doesn't matter?

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Previous Owner re-wiring is usually from lack or money to properly replace what isn't working, lack of common sense electrical knowledge, lack of 620 truck knowledge (how things work) and installing shitty tape player/fog lights/CB radio or any combination of the above, liberally sprinkled with short cuts.

Yeah, I saw a bunch of this when I bought it. And, to fix it properly I just needed steered in the right direction.

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"A little ribbing of the OP is also welcome"

 

Challenge accepted.

 

It sounds like you're new to the vintage/classic/collector/old car community, otherwise stuff like this wouldn't lead you to expletives. If you are new, then welcome. If you're not, then I apologize for my judgement.

 

There are many ways in which a L20B could have found its way under the hood of your truck, but the only thing that matters to you is finding out which accessories (manifolds, carb, distributor, etc) are on the L20B now. Some changes occurred between the '74 L18 and the later L20B so if the later bolt-ons are present, then you might consider finding '74 correct replacements. The carburetor and intake manifold are the two items I would be concerned with. If the truck is old enough (not sure what your emissions laws are like up there), I would scrap the OEM carb anyway and bolt up a DGV Weber.

 

The exhaust manifold also may be different as some of the cylinder heads had round (less desirable) exhaust ports.

 

These engines really are very simple so with a little research and knuckle busting, and not that may dollars spent, you should have a good little runner in no time.

Lol, actually.. I just curse... A LOT. I'd love to blame the career path I've chosen, but let's be honest.... people that curse frequently usually know better jokes and are more fun to drink with.

 

I could laundry list cars I've had, but here's the summation, I basically took a ten year break. I'm no pro like some of you fuckers, but I started turning wrenches on my own shit in 94'. Feel free to continue to talk shit though, my skin is thick. This is after all, the Internet. The only thing that would upset me is getting banned, cause then I'd have to do this without you guys.

 

I'll look at upgrading the carbs. I was doing some passive research on the mikumi side drafts, but I'll do a lot more reading. Right now I just need a new air filter. Emissions aren't a problem here for anything over 25 years.

 

It does have U67 on the head, is this the more desirable?

 

My target hp will be... decided after all the other problems are fixed. I'm gonna have the seat reupholstered and fix some rust issues. I'm thinking 130 hp though. I haven't really pushed it but it seems happy at 55 mph. Our highways are 60-70 mph so. I won't really be using them.

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I could tell it was a U67 because you have the L18 intake on it with the water cooled runners.... and it isn't connected up. The U67 head does not have the coolant holes in it to match up to your intake. The point of the intake coolant lines is to warm the intake in cold weather and cool it when it is exceedingly hot out. A warm intake vaporizes the fuel more efficiently when cold out. The L20B with the U67 head used an intake and exhaust that was bolted together to transfer warmth. I think it a poor set up and from '78 on, Nissan reverted back to the coolant runners like the L18 had. If you have drive ability problems in  extreme cold or heat this is likely why. The U67 head was used from '75 through '77 and is a good match for your L18 exhaust.

 

The starter, alternator, distributor, water pump, manifolds, heads all swap. L20B and L16/18 flywheels do not.

 

If you want 130 hp swap in a KA24E or KA24DE. Makes 145 hp all day and cheaper in the long run. 

 

 

Len Robertson is up near Sprague. 

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Your underhood picture looks like MY '74 (with an L20B and a Weber on it).  Mine does have a few other changes, like electronic ignition, and I have a different weber.  But basically the same swap, quite common.  Rare for the engines to match on these any more, I've had two out of 20+ Datsun trucks I've owned that had the original engine, and in both cases the original engine was in the bed.with a replacement under the hood.

 

Water pump from a '74 may or may not work- it depends on what's on there now.  A '74 water pump did not have a fan clutch, everything after (75+) did, so if you buy a '74 pump and try to replace the '75-77 type pump you MIGHT have now, you'll find you don't have a pulley to replace it with.  So, you need to look under the fan shroud and see if there's a fan clutch or not.  Fan clutch=yes, you'll need a '75-77 type pump.  Fan clutch=no, you need a '73-74 type pump.

 

Starter is the same. 

 

Alternator SHOULD be the same unless someone rewired it.

 

You have a '74 type radiator so you still need to get '74 hoses when replacing them.  Later radiators had the upper fitting on the other side.

 

Your master cylinder looks like a stock one.  At least yours has the correct reservoirs.

 

The air filter is a typical Weber cleanable filter, you can either get a new one or get a cleaning kit and wash it/re-oil it.  Sort of like a K&N type cleanable filter, same material.  I keep 2 and rotate them- install the clean one, then clean the dirty one and store it until next time.

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I didn't read your thread yet. I will though.

Besides, you have already gotten the answers you need.

I'm more interested in where you live. Your profile says Eastern WA. I'm in Pasco.

Yeah, I'm in Richland, Wenatchee, or Moxee. Currently the truck an I are both in Richland.

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I could tell it was a U67 because you have the L18 intake on it with the water cooled runners.... and it isn't connected up. The U67 head does not have the coolant holes in it to match up to your intake. The point of the intake coolant lines is to warm the intake in cold weather and cool it when it is exceedingly hot out. A warm intake vaporizes the fuel more efficiently when cold out. The L20B with the U67 head used an intake and exhaust that was bolted together to transfer warmth. I think it a poor set up and from '78 on, Nissan reverted back to the coolant runners like the L18 had. If you have drive ability problems in  extreme cold or heat this is likely why. The U67 head was used from '75 through '77 and is a good match for your L18 exhaust.

 

The starter, alternator, distributor, water pump, manifolds, heads all swap. L20B and L16/18 flywheels do not.

 

If you want 130 hp swap in a KA24E or KA24DE. Makes 145 hp all day and cheaper in the long run. 

 

 

Len Robertson is up near Sprague.

 

Excellent. This is a whole lot of answers.

 

Ahhhh the KA... we're well acquainted... I have a lot of other shit to do to this before I'd go KA, or actually worry about upping HP output. Most of my steering components need to be redone, some immediate attention to having a poorly repaired pass floor board and other general maintenance.

 

I'll be slowly working down that list on this truck, then, when it cycles back in next winter... maybe. I'll figure it out. I don't like to jump head first into a swap without having a solid game plan.

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Your underhood picture looks like MY '74 (with an L20B and a Weber on it).  Mine does have a few other changes, like electronic ignition, and I have a different weber.  But basically the same swap, quite common.  Rare for the engines to match on these any more, I've had two out of 20+ Datsun trucks I've owned that had the original engine, and in both cases the original engine was in the bed.with a replacement under the hood.

 

Water pump from a '74 may or may not work- it depends on what's on there now.  A '74 water pump did not have a fan clutch, everything after (75+) did, so if you buy a '74 pump and try to replace the '75-77 type pump you MIGHT have now, you'll find you don't have a pulley to replace it with.  So, you need to look under the fan shroud and see if there's a fan clutch or not.  Fan clutch=yes, you'll need a '75-77 type pump.  Fan clutch=no, you need a '73-74 type pump.

 

Starter is the same. 

 

Alternator SHOULD be the same unless someone rewired it.

 

You have a '74 type radiator so you still need to get '74 hoses when replacing them.  Later radiators had the upper fitting on the other side.

 

Your master cylinder looks like a stock one.  At least yours has the correct reservoirs.

 

The air filter is a typical Weber cleanable filter, you can either get a new one or get a cleaning kit and wash it/re-oil it.  Sort of like a K&N type cleanable filter, same material.  I keep 2 and rotate them- install the clean one, then clean the dirty one and store it until next time.

I'll order another one, and pick up the right spares. It looks like I need a valve cover gasket, so I'll start working on that after lights work.

 

IMG_0954_zpswf8kqokr.jpg

 

I think most of my rear light issues stem from this lovely bumper.... they tried to wire the license plate lights to this by splicing... anyhow more to come as I move forward.

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That's rad. You live here? We got a few people around.

We have get togethers. People from Spokane and Yakima come out to hang.

Technically... I "live" in Moxee.... but I'm there as fucking rarely as possible. It's not a bad place, I just love yakima as much as I love herpes.

 

You're much more likely to find me in Richland or in the woods around Wenatchee. Due to it being officially winter until some fucking varmit says otherwise... I'll be mostly in Richland. Annnnnd by mostly I mean 99.9%.

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Cool. Would love to meet up some time.

Being snowy and cold, my 521 doesn't get out much.

Sure, my 620 is in hiding until such a time as I sort a few things out. I'm around though and I'd be down to meet up and talk shop regardless.

 

Back on topic; this is gonna seem like a stupid question but for wire management, and maintenance records purposes, I'd like to do cap, rotor, wires, and plugs. Do I need to do the points at the same time?

 

Are their "Ratsun approved" (no shit, that phrase was used on Amazon) tune up parts? I've had good luck with NGK parts in the past, but I dunno how those work with the Datsun gods.

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NGK plugs and wires is highly recommended for use on Datsuns. I think they come with them. If they make caps rotors and points, get them also. But definitely the plugs. 

 

Points are cheap, easy to replace and may eliminate a current or later problem you don't even know you have. IIRC you can get about 10K out of a set if you file and set them at 5K. Hell it's probably cheaper to just replace them every time.

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NGK plugs and wires is highly recommended for use on Datsuns. I think they come with them. If they make caps rotors and points, get them also. But definitely the plugs. 

 

Points are cheap, easy to replace and may eliminate a current or later problem you don't even know you have. IIRC you can get about 10K out of a set if you file and set them at 5K. Hell it's probably cheaper to just replace them every time.

Excellent, I'll track them down. I used NGK on my previous 240SX/S13 projects and I run them in my Toyota 22RE's.

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