720LA

Thanks all. I'm encouraged by K_trip's comments. Think that's how I'll spend my Friday off work. Maybe I can repair it. If not, I'll hit all the local pick-a-part yards. Happy holiday to all.

I'm wondering if anyone knows an alternative to buying an exact replacement for the turn signal switch. They're so damned expensive and my 1980 720 has a bad one. It's the non-intermittent, non- cruise control. I'm not really worried about authenticity. Right now it sort of works because I have a rubber band supplying a little bit of pull toward the dashboard. But I always have to remember to turn the left signal off. I'm pretty sure I can figure out a separate switch for the high beams.But finding an aftermarket turn signal switch that would fit the steering column might be kind of challenging. No? Anyone done it? thanks, Scott

Yes it really is getting about ten, and it's entirely possible that its a combination of things. You mentioned stuck open thermostat? Its got no thermostat in it. Would that impact gas mileage? Very interesting. I also read somewhere that an exhaust leak before the catalytic convertor can have an impact similar to a vacuum leak which is interesting. Maybe I better start fixing things one at a time and see what effects the way it runs and the gas mileage. I'll post each time I get some stuff done and let you know what the results are just for posterity.

Another good point. The plugs have been in long enough now so that I should be able to check that out. I'll check that tonight and maybe adjust the valve clearance and take a good look at the ignition circuit wiring to look for iffy connections. Thanks for staying in touch on this.

Thanks a lot for taking the time to try to help. I'm still baffled though. New plugs, wires, cap and rotor. Fuel level looks good when running (maybe even slightly low,) choke is open when warm, timing could be retarded by at most 1 or 2 degrees but I'm sure it wouldn't be enough to make it run this bad. Vacuum advance works. I can smell gas but not raw gas - it just smells like it's running really rich, and it's probably just because I've got some exhaust leak and rusted out floorboards so I'm just getting exhaust smell. (I haven't wanted to spend money on the exhaust until I can be sure I can get it running better) No fuel leaks - no puddles. Valve clearance is a good question, but the problem seems like it gets a little worse and then a little better, so that doesn't seem like a valve clearance issue to me, but I could be wrong. Maybe one evening this week I'll go through them and see if that gets me anywhere. Even when it's a little better though, it's bad. It has barely any power and I really have to avoid hills. If the matchbox is bad it wouldn't be intermittent like this - right? Isn't it the case that it's either bad or not bad? Another thought I had was that maybe I should start replacing wiring. Maybe there's a bad ground someplace or a bad connection somewhere. Anyway, again, I appreciate your help. Scott

Hi all, My L20B engine runs awful, and I'm not sure if the problem is electrical or if it's fuel. I'm leaning toward carburetor issues though, because it also gets less then 10 mpg. The only reason I was even thinking that it might be electrical is that sometimes it cuts out like the spark gets interrupted. But from reading up on this site about how the carb works I think maybe the BCDD Solenoid is stuck and is constantly enriching the air and fuel. Does that make sense? But for the price of that solenoid I could buy real estate in NYC! What the hell! Anyone know any way to solve it that is more affordable? Or better yet - how do I test it so that if I"m wrong about it being stuck I don't waste time and money? I really don't want to give up on this truck but I just can't get it to run decent. Any help would be really appreciated. Thanks, Scott

I would like to try this mod for practical reasons. I'm not sure my matchbox works. the truck has multiple problems. One of them is that it feels like it's losing sparking intermittently. I'm thinking if I can try a different module cheaply it might be a good way to figure out if my module is bad. Does anyone know how to wire it up to take the place of a matchbox?

Hello everyone, I'm wondering if anyone can tell me how to replace my matchbox with the Chevy module. I've got a 1980 720 with the L20B that has only four plugs and the matchbox dizzie. After hearing about this mod I did an image search for the HEI module and I see several variations on the number of prongs that they have. I see one that has only two prongs. Would that work? Would love it if it increased the spark a little bit - especially if it saved money over buying a replacement matchbox. thanks, Scott

Thanks to all. Having access to the workshop manual is really a great resource!

Does anyone know if this mod would work on my 1980 L20B in my 720? I'd really like to try it. Mine is barely running now and I don't want to spring for the price of the matchbox module if I can avoid it. Thanks for any advice anyone can offer. Scott

Thank you all. I think I am going to buy one from a newer year now that I've read all your comments. Even if there is something or other that I have to modify, as long as the basic shape and dimensions are the same I don't mind a little extra work to get clean gas into my carb. Alright! Thanks!

Hi all, My gas tank on my 1980 720 is a mess. I've worked on a motorcycle tank before and actually cut it in half, welded a big patch in one half and welded it back together. But it was a lot - and I mean a lot - of work. I'd rather not do that with my pickup's tank but I have to do something and I can't find a replacement. I can only find them for 1982 or 1983 and newer. Come to think of it I'm not sure they were Kingcabs, which mine is. I think mine is approximately an 11 gallon tank which is making it kind of hard to find anything similar. Everything looks like it's just a little too big. Does anyone know of a tank of similar size and shape that I might be able to adapt? I keep toying with the idea of finding a small plastic tank from something newer and trying to adapt it. Or - any other ideas? Come on you Datsun geniuses! Let's get thinkin! Scott

Hi everyone, I have a rough 1980 720 King cab and I would love to start making some real progress on its many many issues. I mean, this thing has really got some issues. Actually some of it's issues have their own issues. The wiring is a complete mess and I'd like to - one circuit at a time - start getting everything working nicely. In order to replace the blower motor circuit, I need to figure out where in the circuit everything belongs. I've looked at wiring diagrams but they don't really give me an accurate understanding of how to simply replace the whole circuit, which is really the route I want to go. I don't want to bother with trying to figure out where shorts or bad connections are, because I think they are so plentiful that I'll be too old to be allowed to drive it by the time I get everything working. So I just want to disconnect power from the old circuit and run it through a correctly rated fuse, through an appropriate relay, through a switch and through the three speed resistor thingy, and then to the motor. But I don't know the order of those things. Is the relay supposed to be before the switch? Can anybody lay some pearls of wisdom on me? Thanks folks, Scott

Thanks for the replies. Much appreciated.

Hi, I have a relatively rust-free 1980 720 that needs a ton of work. I think I want to keep it though, for all the obvious reasons. It's light, easy to drive, great visibilty and there's just something about it that's adorable. Having said that, the gas tank is really pissing me off. It was full of rust. I did the nuts and bolts and shaking and draining and doing it again and doing it again thing. That was exhausting! Put it back together and then found multiple pinhole leaks. Cleverly plugged em with screws and rubber washers. That worked. But I have two fuel filters - the original by the tank and an inline up in the engine compartment - and they both keep filling up with rust. I either have to cut the tank in half and weld in new metal (really don't want to do all that welding!) or find a replacement tank. I'm under the impression that this tank was only used in 1980. Does anyone know? Or is there another tank that I might be able to easily adapt? I'm sure I can take some measurements and go to a pick-a-part yard and find something close that I can make work, but I thought there might be a Datsun fan somewhere that knows just the right tank. Please? Scott