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I got it one piece at a time........


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I purchased my 4wd 1986 and 0 720 pickup about six months ago from a family friend who decided he was done messing with it for $900. It did not run. I had been looking for a small pickup that could get good gas mileage and haul around my tools for summer work (still working on the MPG part), I was looking at toyotas and Nissans and trying to figure out which one to go with and now I am sold on the Nissan/Datsuns. After messing with it for a couple hours we fixed stuff like spark plug being backwards and messing up the firing order and got it kinda running.




After getting it home we went to get fuel but it did not make it to the filing station and left us on the side of the road, so we eventually figured out it was the ignition control module due to information on this forum, so I bought one at Oreillys (oops) then after burning up three of them I asked for my money back and paid more for a descent one. It was still undrivably gutless so we advanced the timing all the way and cleaned up the carb and fixed air leaks and stuff, but it could still barely climb a hill. Then my mom was driving it across the bridge at rush hour and we figured out what was wrong, the timing chain tension-er was in the oil pan and she was high and dry. The valves had contacted pistons and it was sucking air from the exhaust and blowing it out the carb. I was gonna buy and 720 84 with a blown up trans to donate my trans to, but it sold before I made it to pick it up and out of sheer tenacity decided to keep going with this 720. So I had a friend pull out the 1985 engine and put in a used 1984 engine from a wrecking yard at 236931 miles (yeah it is on its third engine). Now it works most of the time. I did break pads a couple days ago and have a line on some manually locking hubs, new fenders, and I need a tailgate and a couple other things. I have made a couple posts since I joined a couple days ago, but I decided I needed a build thread as this is not going to be a quick and easy project. It still leaves me on the side of the road regularly (read about once a week), but it is a good first rig to learn on and thrash. What seats can go in these? Mine are shot and I will be making a run to the wrecking yard soon.












Edited by captain720
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Average fuel mileage on these bad rides is in the mid teens, just fyi. Not impressive.


Rodeo seats are known to bolt in. I believe dodge neon also. Do a Google search "ratsun 720 seat swap" or similar to find more info.


Is the vacuum advance hooked to the carb?


You can remove the black plastic can in front drivers engine bay. Its the vapor canister and since it's Not hooked up, you can just pull it. The one line remaining likely goes back to the gas tank. Just plug that hose with something. I use that box to hold spare fluids.


The brass nipple on the carb, connected to anything? Take a closer up couple of pics of the carb area.

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The brass nipple on the carb is not connected to anything, thanks I was just about to ask about the canister. Also the big silver tube things that are connected to the exhaust manifold, do I even need them? Or can I just remove them and plug the holes with brass plugs? They are ugly and get in the way. 

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If I lay the hammer down at a stop light or something it really stumbles and lurches and does not accelerate quickly, but if I start slow it goes nicely. It makes very little power under 2,000 RPM, but once it gets there it hits the power band like a two stroke and will put me back in the seat if I hammer it then. Is it normal for these to do that with the Weber? Or is it jetted wrong? How do I know if i have the 38/38 or the 32/36?


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Nipple might cause vacuum leak, can't tell in pic where it really goes on the carb.


Tubes to the exhaust manifold were for secondary air injection to help the catalytic converter function better. Yes they can be removed and plugged if you have no emissions to worry about.


I strongly suggest driving the truck till the exhaust is stupid hot, then soaking the retaining nuts liberally with PB blaster. Then doing that 3 or 4 more times. Then get a wrench on one while and use impact to break them free. Hit the wrench repeatedly with a hammer till they pop loose.

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Could be indicative of tuning issues, bad accelerator pump, or vacuum leaks.


However the 32/36 often slugs if you gun it as at 2/3 or 3/4 throttle the second barrel snaps open. Below that you are only on the 32mm barrel in the carb. Above that, you are using 32mm and 36mm barrels. 32/36 is known a progressive carb because of that two stage setup. The 38/38 is a synchronous carb, using two 38mm barrels equally together all the time.


Take close up pics of the carb all the way around, best you can. Take the top off and take a couple pics down the carb as well. We can help you identify which carb.


Unsure about the nipple just now. Start by plugging it with just a rubber vacuum cap and go from there.

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Welcome to Ratsun


The brass nipple on the bottom of the carb on the pass side is for the vacuum advance. It goes to the distributor.

Just below it is the air/fuel mixture adjustment. I don't see that hose, just spark plug wires.



A 38/38 Weber has same size barrels, on a 32/36 they are different sizes.


Granny in hotpants, photobucket is slow tonight.





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The last engine was backfiring out the carb so bad that it soaked the filter in gas, that is why it looks crumpled and funny. The gas makes it expand and crinkle up so that the clips press down and make it look weird, I will get a new one next time I am at the part store. What filter do you guys use? I have an EMPI one on right now.

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That's the EGR valve. Part of the smog system.


Lockleaf makes a good point about having to smog your truck.


I don't have to so the only vacuum lines I have are the power brake booster and vacuum advance to the dizzy.


The egr valve, cat converter, secondary air injection lines, and probably some other stuff are all gone.


Keeps it simple.


The barbed brass fitting you have on the top front corner is plugged on mine.


Looks like you have the vacuum advance hose for the dist.

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Shiny thing is your egr valve. You can just ignore it. That vacuum connection on it won't create a vacuum leak or anything. Removing it requires making a small block off plate and plugging a pipe on your exhaust manifold.


Is your truck engine cold or hot in that photo? Where does that black wire (which is attached to your electric choke) connect to? And the black vacuum line right below the electric choke, where does that connect?


Take a pic looking straight down the carb. I'm not good enough to be sure but i believe you're running a 32/36.

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I live on the East side of the mountains so no smog checks over here! :) Little black vacuum line goes to the dizzy, the electric choke is currently drawing power from a coil (more of a side of the road fix, I will make it better as soon as I have time). I drove about 5 minutes before taking the photo, but the temp gauge was not much above cold.


Is there supposed to be something filling these holes on top of the valve cover?




Gauge was almost up to halfway like normal in this photo.



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"It still leaves me on the side of the road regularly (read about once a week)"







Welcome to old car ownership & welcome to the circus we call Ratsun. Like that truck.

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Choke sounds like it's working fine then.


I still can't tell about the carb:)


Are the brass colored plates the same size or different sizes?


Swap the vacuum hose from the carb point it's on to the brass nipple. Cap the now open vacuum connection. See if truck driveability improves.

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