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Betty Boop - 72 Datsun 620 - Build log


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Hey guys, I decided to track the information and research in the process of building up my 620.

She's got unknown miles, bought from a kind older Mexican guy who barely spoke English and really stretched my Spanish skills, drove her home with the stupidest smile on my face.

 

Base Condition:

1972 620 Shortbed Single Cab

Stock rims, mismatched tires, gotta love it

L16 with Hitachi SU carb

4 speed transmission with a ridiculous amount of shifter slop

Leaks from everything, everywhere. Even the gas tank.

Ripped seatbelts

Some fancy upholstered seats

A stereo that only turns on when the ignition is on but not running with bare speakers stuck to the back of the cab by the driver magnets (now all in the trash, they were 8 ohm home speakers)

Cracked windshield

Leaks in the windshield seal

Odd bends in the hood corners that don't line up with the fenders

Coat hanger battery hold down

No center mirror

Side mirrors have blindspot mirrors on opposite sides for some reason

NO RUST

I'll add more stuff as I find it

 

Security of a 70s Truck

So far, I've been working on being able to lock her up when I take her out.

 

The lock mechanism on these trucks is weird. It only functions when the door is closed. Which is a bad design, in my opinion. I like opening my door, locking the door, then closing it. Can't do it on these. For some reason, the drivers' side wouldn't function, so I pulled the mechanism out and found there was an interference with the lever that attached to the lock rod and the lever that actuated the latch. Definitely wasn't going to be able to bend it back into place and it honestly didn't look bent, so I took a Dremel and ground down the lever until the lock lever would slide into place. Only took a little meat off the latch lever anyway.

 

It'd be interesting to see if there's a modification that will allow these doors to be locked while they're still open, but the way this mechanism is set up I'm not seeing a way to do it. I'll definitely be checking out the latch mechanisms in the later Nissan D21 for reference and to see if they're easy to adapt.

 

I bought some replacement door lock cylinders for a late 90s Pathfinder and a couple strips of sheet metal. The 70s lock cylinders Nissan used were terrible, and it's now 45 years since these locks were built, soooooooooo. A little filing and drilling and the door keys will have a nice little upgrade. Doesn't hurt that you can't really find replacement lock cylinders anymore.

Also got a chance to use the 3D printer to make a lock rod knob.

 

Pictures of this process coming soon.

 

I'll be updating this as further stuff progresses.

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I may not have understood your instructions, because when I tried it this morning nothing happened. The door remained unlocked. Did they have that feature in the early 620?

Also correction, I found out it's not actually a Hitachi SU carb, it's the Hitachi HI-2. Haven't found the 72 FSM floating around so I've been using the 73 FSM for reference, but there are a few small differences.

 

Ignition Inspection

Pulled off the dizzy cap this morning out of curiosity and realized not only is it dual points, the second points set is completely snapped! The guy did try telling me something about los puntos but I didn't quite understand what he was telling me was wrong with them. Now I know. Luckily, the previous owner has a small treasure trove worth of the little parts you wouldn't expect to find, so there were two practically new points sets included in the spare parts. Swapped one in and adjusted to .020" gap with the lobes at peak height. Don't know how to check dwell though. Never had a car with points type ignition.

 

Also found out the spark plugs were some worn out Champions with nearly no electrode left sticking out of the insulator so I got a set of AC Delco R43XLS -- These are the ones with the protruding insulator element of the original NGKs and the same relative heat range, and Autozone had them in stock. So I slapped em in. I can't really see the timing marks on the wheel so I also picked up some Wite Out to mark the notches. On this one apparently the first marking on the wheel is actually 5*ATDC, but it also has the most prominently ground notch. I did verify the second notch was TDC by pulling the valve cover off and while I had the spark plugs out. Borrowed the lady's nail polish and a spare paint brush so I could mark ATDC in pink and the rest in white. 

 

Afterwards confirmed after warming up the timing sits at about 9* BTDC, with about 3* of variation at idle. But seeing as I don't have a tach, and the idle sounds high, I'll wait until my optical tach comes in before dialing in the timing. I guess it would make sense for the timing to be a little advanced if the idle is too high. 

 

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Use the NGK/Nippondenso as many US spark plugs will have a slightly differnt pitch on the thread and it becomes hard to get out later even with antiseize. Had this happen with the Motorcraft plugs.

The 2nd set of points is for like 3rd gear switch and I really dont use the 2nd set of points myself anyways

 

 

I put 10-12 deg on my 521 pick up

 

 

High idle might be choke still on?

 

 

change out fuel filter

Edited by banzai510(hainz)
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All Datsun cars were this way, I think the truck was too. Open door and get out. Push the door lock down. Hold the outside handle up while closing the door. Door should lock. Tell the truth I had a '78 620 and... I can't remember.

 

0.017" to 0.22" points gap is perfect.

 

Only use NGK plugs. B6ES This is right out of the '73 620 Factory Service Manual.

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The 73 was equipped with an L18 and L16, right? Would that be the same plug in the L16 for the 72? The NGK part number I have for the 72 is BP5ES, and B6ES for the 73, but I didn't find the part numbers in the service manual, just torque specs and gap specs. I got the part numbers for the spark plugs from davidcmurphy.com. Excellent source of manuals and write ups, as is datsun510.com.

 

Side note, while going through the piles of parts under and behind the seats I found a paper copy of the 79 service manual!! So that was a total score. 

 

I'll take Mike's recommendation for the B6ES. Some more research and a bunch of people mention the L series really only likes the original NGKs, so yeah I'll be swapping back out to the brand name. Only difference I noticed in the two is heat range and the B6ES doesn't have the projected electrode like the BP5ES. I don't understand how the transmission gear can activate the second set of points. Is it electrically activated? Vacuum? 

 

I might be doing something wrong with the whole door thing, but I'll look at the mechanism again after I get the new lock cylinders to swap in. Currently when I press down on the rod and pull up on the handle, all that happens is the door doesn't shut at all and the lock rod stays up. The cylinders just came in the mail today, so I'll be installing them over the next few days. Right now they look like they'll be almost a direct swap. 

 

To Weber or Not To Weber

The tach came in. It's idling at about 1600 rpm warmed up, dropping it any lower and the engine shuts off. Choke stays shut, and the engine won't run with the choke opened manually, even after warming up. I suspected a vacuum leak, so I went to the local parts store, picked up a fluid displacement pump, and picked up a pack of cigars from the gas station. Hooked up the cigars to the inlet of the displacement pump, and the brake booster nipple on the intake hooked up to the outlet of the pump. I found smoke coming out of both the throttle shafts on the carb. Quite a lot too. This would explain why is was so freaking hard to limp the truck home when I bought her. A closer inspection also showed the Hitachi was leaking fuel from the top segment of the body and the middle segment of the body. Debated about a Weber 32/36 swap or rebuilding the Hitachi, but the lack of documentation and parts support for the Hitachi sold me on just getting the Weber. Yes, the rebuild procedure is in the FSM, but still. Also, even regasketing an old Hitachi won't fix the throttle shafts leaking. So that's out the window. The base plate gaskets alone are nearly impossible to find. A new Weber is, well, new. So I'll be following the Weber tuning guide on here with that. 

 

Appeasing the Landlord

I got my first nastygram from the landlord today, a warning about oil stains on the pavement. It's a fair complaint. The old girl definitely has some incontinence issues. So on top of the new carb to get her running, I'll have to at the minimum change the oil pan, oil pump, and valve cover gaskets. I went ahead and ordered a master gasket kit with the spark plugs. I'll be running a compression test in a few days to verify the head gasket condition, but I really don't want to change it if I can avoid it. I expect the exhaust studs will snap if I tried to remove the manifolds at this point, and I don't want to deal with that at the moment. I'm riding this lease out until I can get a proper garage to do some of the more exciting stuff. 

 

Ok, Maybe Some Rust

So I looked deeper under the parts and nonsense left laying around the truck, cataloging an inventory as I went of all the sweet stuff that came with it. Betty's got some surface rust, but nothing terrible, honestly. The back of the driver's side will need to be addressed relatively soon, but I want to replace the rear window (it's a combination of broke glass and silicone) and the front windshield seal before addressing the surface rust. I hear people despise rust encapsulators or rust converters. In the same breath I also hear people warn against aggressive sanding and oil-canning. It's down the road from the work being done now, but it's on the horizon. 

 

Lock cylinder swap pictures coming in the next few days!

 

 

 

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On ‎11‎/‎14‎/‎2018 at 12:50 PM, datzenmike said:

When locking. try pushing the lock button down. Then lift up on the outside door lever while closing the door. Door is now locked.

 

Datsun did this so you can't accidentally lock the key in the vehicle.

along with almost every other older mazda, Nissan,ford,ect 

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The L18 was only used for one year... '74. That's a build date between October '73 and Aug '74 found on the driver's door jam.

 

B6ES is the correct plug for a '73 L16. If you look behind the dip stick handle on the side of the block, the engine size is stamped there on a flt boss. 6 and 5 is the heat range with 5 a colder plug. The P is for projected tip.

 

Check the intake for any hoses that may be off. Pinch the large brake booster hose at the rear.

 

Gas shouldn't leak from the carb.... check the fuel level on the front glass. May be over filled and flooding

 

Door. Yeah I probably am wrong about the truck door locks. Cars work this way. Try spraying the latch mechanism with WD-40 first.

 

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is the speed screw for the carb turned in all the way?

maybe the idle jet is plugged.?  look at the fuel filter and open it. If lots of dirrt and rust maybe thats it.

 

as for the 2nset of points On truck I could never fint where this switch is. On 510s its on the fire wall. Really who cares run the single set of points and adjust to say 10 if possible. the the points on the engine side with the bigger condensor

Edited by banzai510(hainz)
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Transmission switch for 4th gear. I think no advance below 4th gear? Also a carburetor or throttle switch for idle and full throttle (again I think) some have a temp sensor in the cab so no advance when below 50F. 

 

Just remove the second set and time it properly and you have full advance all the time!!!!

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It looks like the 92-97 Hardbody lock cylinders are practically a drop in swap for the doors. (Well Auto P/N DL-NS-92) The keys are the same style, and I was gonna complain about it literally being essentially the same construction as the lock cylinders of 20 years earlier, but the feeling of being able to walk away from a locked truck feels much better than walking away from a truck that anyone could open. Only issue was flipping the lock clips to the other cylinder and installing the passenger side cylinder in the driver's door and vice versa. 

 

I didn't really feel like pictures were necessary considering how simple it was. I'll take some anyway when I have some daylight, I typically work on the truck at night. The lock rods snap into place on the levers of the new lock cylinders, and need minimal bending to get the actuation just right. The tactile sensation of locking the door feels overall mushy. I think lightly notching the door lock lever in the lock mechanism may increase the feeling of the lock snapping shut. I have an idea to modify the door latch to lock while it's still open, but that'll wait until the engine is running right. 

 

Don't LS Swap It!

Thanks for the tips on the ignition setup. I didn't know that removing the second set could actually be beneficial. I'll study the FSM some more and try to understand the layout. There is what appears to be a rudimentary throttle position switch attached to a bracket that sits on the carb base mounting studs. Perhaps that controls the timing switch. 

Since I'm considering the Weber conversion, I'll also be considering electronic ignition. I don't want to regularly be gapping my points every 6 months and replacing them every year or so. But I refuse to go any further into the conversions until the engine is running right. Determining the Hitachi to be a problem point, and, after pulling the carb off and verifying nowhere else leaks when I tape off the intake opening with the smoke tester, I've decided I'll go with the Weber carb conversion. I'll try to get her running well with just that. I generally don't like parts swapping unless I'm sure of the benefits of the parts swapping.

 

So now for the waiting game.

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The Lock Cylinders Strike Back

The lock cylinders setup is actually picky now that I've been running it for a few days. At first I didn't notice it, but it looks like the cylinders don't actually return to their centered positions after locking or unlocking. I'm having trouble visualizing how the linkage would have to function to allow the lock rods to move back to center without interference with the levers in the latch, but I have another set of latches on the way for experimentation. I have a feeling there's an elegant solution to all this, but it hasn't hit me yet, and I'll continue to play with it until I find an answer. 

 

It's Working, It's Working! ...Okay No It's Not. 

The Weber swap worked beautifully. Per the instructions I did go and grab a static fuel pressure regulator to plumb into the fuel inlet to the new carburetor (Mr. Gasket P/N 9710) and installed an inline fuel filter in addition to my original fuel filter I had near the firewall (changed the element in that one). I did unhook the vacuum advance as some had recommended, and capped off the line on the intake. Fired right up. Idled at 600 rpm, sat happily there with a nice little loping sound. 

Okay maybe not so beautifully, to be honest. I had to limp home after about 30 minutes of driving around town, testing it out. Suddenly the engine just lost power, refusing to gather speed under load, but would rev up fine under no load. I never learned how to diagnose rich or lean conditions from feel alone, but if I had to guess, I'd say it felt lean. The only thing that would get her back up and running well enough to get home was to crank the fuel pressure up to 3.5 psi from 3 psi.

Maybe I popped the diaphragm of the mechanical fuel pump from the additional pressure before the regulator? I know using a returnless static regulator will increase pressure before the regulator as a side effect of decreasing the pressure after. So now I need some fuel pressure data. 

I don't have a fuel pressure gauge that measures in the realm of 0-15 psi, mine is for EFI systems 10-150 psi. That's on the purchase list, along with some stainless steel pipe fittings to tee into the supply line for the carb. 

 

Side note, did run a compression test, and cylinder 2 is sitting at 140 psi cold, the rest are 155-160 psi.  I'll run the test again with a warm engine, see if the numbers are any different. 

 

Sorry for the lack of pictures. I tend to get into working on it and completely forget about taking photos until I'm already done for the night. 

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 the vacuum advance runs from the base of the carb to the distributor. pretty simple. You should run it.. Never run the vacuum adv from the intake manifold. throws the timming all off.

 

 

1/2hour??????of driving? choke still On? or not working roight after warm up.

 

cylinder 2 might need valve adjustment but should stillrun fine at 140

 

why the pressure reg? if stock fuel pump then its not really needed.  remove it and see if that is the proplem.

If ypou popped a diaphrame you might get a gas in the oil crank case so smelll for gas.

Fuel pump workes or it dont..pull the output hose and point in safe directi and hit the key and see if gas squirts out.

 

99% of the webers I installed work right out of the box.

 

 

no need to add all that fuelpressure and gauge crap on a L motor. its fine.

 

see if gas is squirting in carb when you cycle the linkage.This will show the accell poump working and the fuel is in the bowl.

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  • 2 weeks later...

Been a minute. Finals are going on, but that hasn't stopped me from ignoring my studies to have some wrenching fun!

So a few things to update. One, the weber work is pretty much done. Turned out the screws holding the adapter plate loosened. Vacuum leak. Installed with lock washers and threadlocker this time, and gave it one half ugga dugga torque on a 4 inch right hand screwdriver. Drove her around for about a week with no major running issues when fully warm. Two, the rust was worse than anticipated, as when I peeled back the paint it had moved underneath the paint and it flaked off the interior. No rust holes, but one of the cab mount bolts was getting chewed through pretty badly. Sourced two of them from Mcmaster-Carr (12mm shoulder bolts, 65mm long for the rear) and I'll be finding suitable hardware to replace the old nasty stuff. Ideally I'd replace the cabin mount bushings, but the only source I can find is some unbranded Taiwanesium stuff on ebay, or use universal bushings from Energy Suspension (nearly 150 bux for six bushings of unknown fitment quality). I'm not too certain how I'll address the bushing situation, but that's a future me problem.

 

Third, I've got a few ideas going through my head regarding the locking mechanism, and I've printed a few concept prototypes. But I haven't taken mechanics of materials yet, so I'm not too sure which design would function best or fail first. Once I've finished a couple different designs and printed functional prototypes, I'll post some pictures for critique. They're designed to disengage the exterior door handle when locked instead of immobilizing the door handles, and to unlock and open when the interior door handle is pulled. I don't think I'll ever need a deadbolt system. 

 

Fourth, I finally sourced a back glass. It's a solid pane glass, when only sucks a little bit. I kinda wanted one that has a sliding door like my old D21 did, especially with no AC (yet). Paid a bit more than I'd like for it, but hey, it's better than the "custom one off" prices I was getting from nearby glass shops. I'll be looking at Vintage Rubber for seals. There's definitely water leaking in through the old seal, and also through the front windshield near the driver's side I can see where a trail of water runs down during the rain. 

 

Fifth, I've got ripped seatbelts, and one of my friends is studying Materials Engineering and wanted to tackle the process of rebuilding a seatbelt until I can get a new set as I complete the interior. I know it's a lot of work for a normally $100 or so replacement part, but it's a fun study, and she's got a lot of fancy textiles machines I've never even heard of until now. 

 

 

 

Seat Belts, Everyone!

We pulled specs from FMVSS 210 and FMVSS 208 for reference on what needs to be done to keep in compliance. Not that anyone will be testing the seat belts, but to give us an idea of the ball park performance characteristics the belts were designed to perform at. As they came out of the truck, not only were they ripped, the mechanisms that autolocks the belt under a quick pull didn't work at all. So when I pulled them out and inspected them, I noticed one was missing a piece entirely (someone already tampered with these then, and knew they didn't work... sigh...) and the other had a cracked cam that operated the mechanism under sudden acceleration. 

Ia6zT4F.jpg

 

As you can see there's some missing bits.

 

I pulled the cam out and took some quick measurements to get an idea of if it's too tight to work as a 3D print.

TsZkZd0.jpg

Then I went on to model it with its critical dimensions more or less eyeballed off the calipers. 

The printed piece came out nicely, it functions as it should with a definite lock under sudden pulls, and only functions when the belt mechanism is upright. We ordered some replacement webbing from seatbeltplanet.com and my fried went on to measure the stitching sizes and types, and we are now sourcing some suitable replacement thread and looking for standards that define what sort of threads are typically used. So far it looks like multifilament nylon around 60 weight or so would be equivalent to what's already on the stock seatbelts. 

I ordered 7 yards of a charcoal grey 7 panel 2" webbing, which should be plenty for the two belts. They were both pretty bad but looked like they were 108 inch seatbelts when they were intact. 

 

Once we get everything stitched up and back in the truck I'll start looking for replacement seats. The current bench seat sits too high and I can barely see out of the truck, and my thighs hit the steering wheel. It also sits a little too far forward for comfort maxed out. I'm looking at the Bajas from Corbeau, but I'd like something comfortable but with lower seat height. It'll be a tight fit, to be sure. There's a Summit in Arlington, so I'm thinking about stopping by there to sample some different seats.

 

A big thanks to y'all for the help with the carb setup!

 

 

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  • 3 weeks later...

This update is a little more pic heavy, as certain areas have drawn more attention than others and things get fixed.

 

Belt? Where we're going, we don't need... belts.

Haven't had a chance to get into the door latch mechanism yet. I've found several leaks in the cabin that have demanded my more immediate attention, as well as the interior rust treatments (remember when I claimed no rust? silly me). The driver's side seat belt is done, and it seems to be a little too short for my liking even though we matched the length of the broken belt that came with the truck. Maybe that's why the belt broke... Those pictures will be added once my friend who helped me with the belt comes back with her phone that has all the belt pictures on it. It may also hold off until the belt has sufficient length.

Interesting note, the plastic sliding belt clip part was originally a light blue, as was the belt. We had the idea of using clothing dye to color the blue parts black. For the belt clip, it worked amazingly well. For the silicone belt retraction mechanism cover... not so well. 30 minutes in the dye mix and nothing happened to it. We'll go at it again next time around to see if we can come up with a good color change method that doesn't involve paint.

 

Road Block by Fuse Block

The electronics pretty much died on me. No headlights, no park lights, no turn signal, whole bunch of nonsense. Visual inspection showed me a burnt fuse box. I mean, I knew it was gonna need fixing anyway, the previous owner's wiring jobs for the radio and signal flashers did not bode well for any electrical work. It was Christmas Eve, I didn't have any major plans, and decided my Christmas present to me was gonna be a running truck.

WUCyXfX.jpg

Book work shows those are NOT the proper fuses either. No wonder it burnt out. 30 amp fuse... 30 amp alternator... hmmm. HYDV9oL.jpg

Autozone fuse block (P/N BP/FB6-ATM) and a test bracket I hammered out just to get a feel for how it would mount. jAmSATP.jpg

Results of research on the fuse block layout. 72 was different than how 74 and 79 did the layout, but I stuck with the 72 layout because it's a temporary fix anyway.

JqYq3fx.jpgeDhieMC.jpg

3D printed an insulator/separator for the individual blades coming off the fuse block. Thought it might class up the joint a bit more, as well as stop inadvertent knees from bending and blades.

W1Jbg8x.jpg

First test fit. I couldn't get my heat gun out to the truck because of a lack of suitable extension cord, and since that's on the fused side of the circuit I decided oh well. Just put another insulator on it.

Bracket needed a remake with a longer mounting flange to match the holes on the original fuse box. So I made a second one and finished mounting up the box. LFh807T.jpg

Tucked up under and out of the way. I still need to make a label for the cover, but there's an idea involving sandpaper and a laser engraver that may prevail for the cover. We shall seeeeee...

 

 

It's Such a Pain in the Glass

A couple days pass and I get some more free time to do some fun stuff. Decided it's time to install the back glass I sourced from a guy out in California... the only dude I found who was ballsy enough to ship glass through FedEx. Got a new seal from Vintage Rubber and installed the back glass. rwx4IsB.jpg

From this...

 

ivn59td.jpg

To this!

 

I'm going to be treating the entire cabin for rust now, so eventually the window is coming back out so I can address the miniscule rust developments in the mounting, but they really are quite tiny in comparison to other areas of the truck.

 

So some progress has been made. I'm a little bummed I haven't had time to come up with anything fun for the doors yet, but I'm sure it'll come to me.

Still need to make some new paper gaskets and address the mounting issues I keep having with the Weber working itself loose and giving me some lean issues while I'm driving, but I'll get to it. It's also oil change time, though I have forbidden myself from spending any more money on the truck until next payday. I have plenty of parts and materials to keep busy as it is.

The driver's side floor pan is going to be replaced, and I'm debating how to go about it. I have rivets laying around, but I still need to polish my metalworking skills to make a more suitable floor pan. The first and second attempts are pretty much garbage in my opinion.

 

More updates to come!

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