1980 720 king cap

[1980_720_RB]

So on a whim i have purchased an old datsun pick up . I have owned several 84 and 85 z24 datsun/nissan trucks over the years and know them pretty well . With this truck ( 1980 ) i have found the motor is from a much later year , the intake is from an 80's z 24 with the typical 2bbl carb . A lack of power is the most noticeable problem i am having , other than that , after some tuning and carb work it runs very well . So , what is the easiest way to identify the year of the motor ? This would greatly help me to tune the motor and carb and maybe fix my lack of power problem .

 

Thank you -

[Sealik]

Well....if its an 80....should be a L20B...but

Engine leaning the opposite way as compared to the Z22/Z24?

Pics

[wayno]

Welcome to Ratsun

Is the engine carb on the drivers side?

Does the engine have a valve cover like this?

[1980_720_RB]

i just opened this account after a discussion with a fellow in a nice station wagon mentioned the sight - i will try to post detailed photos of the motor and relative parts in question asap -

[1980_720_RB]

My link photos of motor -

[ggzilla]

That's an L20B, so it is about 400 cc less than a Z24.

It's the stock 1980 engine. The Z24 is the newer engine.

 

[elmerfudpucker]

This is the Z24's lil brother a Z22

 

Nice thing about your L20B is you can get mods easier.

[wayno]

That looks like a badass horn on the inner fender well, and it does seem to be an L20b with a stock looking carb, a weber might help with the power a little.

This is my L20b with dual SUs, disreguard the garden hose between the valve cover and air filter, that was before Ratsun, when I used fram oil filters also, I know better now.

[1980_720_RB]

well that clears things up a lot - the carb may just need a re jetting nbd - that is an old aluminum electric organ siren on the inner fender my friends always know it is me out front . i swear by NIX oil filters and , if i could count the times i have used creative fixes - like garden hoses . i am not looking to rat rod this truck however i would like to tow a 12-14' camp trailer with less hassle going up hills . thank you all for your help -

[ggzilla]

L20b with a stock looking carb, a weber might help with the power a little

 

The stock 720 carb flows more than a Weber 32/36.

 

Yes, the 2WD 720 is jetted leaner than the 4WD. So going up a few sizes in the main jets might help. But first just check the site glass, and if the fuel isn't on the line, adjust that, it could make a big difference.

 

But most likely it's just the smaller engine combined with a higher final drive gearset. That makes a HUGE difference in how it feels.

[wayno]

well that clears things up a lot - the carb may just need a re jetting nbd - that is an old aluminum electric organ siren on the inner fender my friends always know it is me out front . i swear by NIX oil filters and , if i could count the times i have used creative fixes - like garden hoses . i am not looking to rat rod this truck however i would like to tow a 12-14' camp trailer with less hassle going up hills . thank you all for your help -

 

The L20b in a 521/620 will struggle with a 14' camp/travel trailer, and the 720 is heavier, that is probably why datsun/nissan put an engine with more torque/bigger in the 720 the very next year it came out, and a couple years later a torque monster Z24, but one has to like the simplicity of the L20b, they have few problems, and as long as you keep oil and antifreeze in them, they last a very long time, and likely can be fixed on the road with a screwdriver, cresent wrench, some duct tape and a fuel filter, which everyone should have one in there glovebox.

I don't know a lot about downdraft carbs, so it may be true about re-jetting yours may help, I just know that most say it made a big differance putting a weber on their engine, but the same results may have been achieved by re-jetting the stock one, or just rebuilding it for that matter.

[elmerfudpucker]

The L20b in a 521/620 will struggle with a 14' camp/travel trailer, and the 720 is heavier, that is probably why datsun/nissan put an engine with more torque/bigger in the 720 the very next year it came out, and a couple years later a torque monster Z24,

 

+1 on that Wayno! My truck is 3k lbs dry and had about 700lbs of gear, the trailer was 800 lbs dry and had about 900lbs of gear from Tacoma WA to Canby last year on I-5 in 5th with no issues! I have hit the CAT scales at 4760 lbs in the truck alone with 80 psi in the monroes and the Z22 did great. L's are easily faster but the Z's have more grunt! ;)

[Skulptr]

Z24 is definetely what you would need for better towing for a little truck. A few months ago, I tipped the scale at the scrap yard at just under 10000lbs. Had a 12' flat bed, and both the truck and trailer were loaded to the gills with steel. I came back again later that day with no trailer, after load out the weight I dropped from the truck bed was 2500lbs. I also added a leaf in the rear too otherwise none of this would have been possible. You might want too look into that too, towing a trailer with toasted springs and shocks is dangerous

[1980_720_RB]

some 14 years ago i had an older dadsun truck (76ish) with an L20 b motor that was out fitted with a mazda intake and a 2bbl side draft 38mm delorto carb any one happen to know anything about that - in all my years as a mechanic i have never heard or seen it again . and yes a good carb tune up and timing the motor is in order for sure -

[1980_720_RB]

also brakes and suspension are the next big rebuild - going with air bags in the rear and have adjust the torson bars on the front as it was lowered and needed to be raised and balanced , with that done the rear suspension is next to be gone through and , this truck will be getting a complete brake rebuild from the calipers/cylinders on up . I took some time to adjust the accelerator pump on the carb and that made a huge difference in acceleration power and it is climbing hills a bit better now . i will find some time to go through the throttle body and check the float position this weekend - again thank you all for your input it has been Very useful .

[wayno]

also brakes and suspension are the next big rebuild - going with air bags in the rear and have adjust the torson bars on the front as it was lowered and needed to be raised and balanced , with that done the rear suspension is next to be gone through and , this truck will be getting a complete brake rebuild from the calipers/cylinders on up . I took some time to adjust the accelerator pump on the carb and that made a huge difference in acceleration power and it is climbing hills a bit better now . i will find some time to go through the throttle body and check the float position this weekend - again thank you all for your input it has been Very useful .

 

If your going to buy new rotors and calipers, I would look into changing over to the vented rotor/caliper type, there just better IMO.

[ggzilla]

Yes, Dellorto carburetor is common. But remember the 1976 pickup weighed a LOT less than the 1980-up pickups.

[1980_720_RB]

new calipers vented rotors and ceramic pads are in order . the side draft was on a L20 b with a ( mazda ) intake that was my curiosity ... tomorrow i will be going through the carb and timing the engine after i am sure everything is right ish , than a test drive probably followed by a post of the results . thanks for the input i will use it as best i can ...

[1980_720_RB]

ill start this with a laugh , the base of the carb was loose - and some of the gaskets were worn - the float is right so with all that repaired and the engine timed it runs much better , smother acceleration and a little more power up hills - i will most definitely be up jetting that carb in the future as i have decided that that might well make the difference i am looking for . thanks again for all the input this forum rocks