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1970 Datsun 521 Z24 Swap need help!


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I bought this 1970 Datsun from a family friend, we thought it ran good until we found out it had a motor knock, so we found a 1988 Nissan hardbody for 50 bucks with a Z24 in it.

 

I want to do a swap from the stock motor in the Datsun to the Z24 out of the 1988 hardbody. I am doing this for my senior project, and my father is a mechanic but he hasnt worked on Nissans much at all.

 

I want to use the weber carb off of the 1970 Datsun motor which (correct me if i am wrong) is the L20B, but the intake is different on the Z24. I have looked around a little bit for a new intake that will fit that carb because the carb is brand new and it would be a shame to go to waste.

 

The next thing is engine compartment room.. I have seen a couple of 240sx motors in the 1970 datsun and they fit fine but they looked to be bare of almost everything, such as battery, etc. We have thought about mounting the battery in the bed of the truck, along with a fuel cell so we can get rid of the gas door on the side of the bed. We also want to do some body work so that the bed will be even with the cab all the way back. But in the meantime for my project in class's stake i am more looking for the Motor details for now. I know that the Z24s tend to crack, and we are going to have this one tested before starting but i was just wondering if anyone would have any other projects they could show me with the exact same motor swap into a 1970 Datsun 521.  Thanks!

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z24 will drop in along with the 5speed if it has one with it. the tranny mount woukld have to be shortened a few inches. I would also look a swapping the axle aswell. or even swapping the 521 body on to the hardbody chassis as im sure the hardbody rides much nicer than the 521 and already has disk brakes. weber can be used on the z24 but my neighbor has an 88 but his is fuel injected. id rather go fuel injected than carbed but that's just me

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Alright cool, thanks man. I don't have much money to spend on this project for rigt now. It is just a throw together for the time being and then I'll fix it up a bunch more. I just need it done by like April. The wiring is going to be hard though because we are pulling all the smog things off of it. We basically want to run only the necessary wiring.

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"The wiring is going to be hard though because we are pulling all the smog things off of it. We basically want to run only the necessary wiring."

 

If I was going to do a swap like this, I would get the Z24 running in the donor truck first.   Then evaluate the engine.  Check compression, or ideally a leak down test.  Check oil pressure.  Look under the valve cover.  Pressure test the cooling system.  Check for any trouble codes, if the engine can store them.

 

Then swap the engine, and transmission together in to the 521.  Randomly eliminating,  and without understanding how all the smog controls work will create problems.   PVC is a very good thing.  It does not rob any power.  Evaporative emission control is a good thing.  Do you want to pay for $3.50 to $4.50 gasoline just to have it evaporate out of the tank on hot days?   Gas vapors stored are returned to the truck when it is cold, and this helps the engine run better when first started and cold.  EGR is often used for preignition control on fuel injected engines, and even if it is not, the engine is tuned for it existing, on engines that do not specifically use EGR for preignition control.

 

I do not live in California, but my understanding is that if you swap a newer engine into an older vehicle you have to comply with all the requirements for pollution control for the model year of the newer engine.

 

It was mentioned to also swap the rear axle.  I do not know what the rear axle ratio on the donor truck is, but a 521 has a 4.375.  That means the engine is turning about 4,000 rpm at 60 miles per hour.  The stock L=16 is happy doing that.  The Z24 probably would like lower freeway RPM.

 

So, if you are swapping the entire powertrain, that might be a good reason to put the 521 body on the newer truck.  You get disk brakes. you get more modern wiring, although wiring on a 521 would be simpler.  But if you plan on adding any accessories, 521 wiring is adequate for a STOCK 521, and no more.

 

One more issue if swapping the 521 body on a '88 hardbody frame.  You probably need the title for the hardbody, and the 521 to make California DMV happy.  You may have to get it inspected, and pass to be able to register it.  Make sure you got all the legal issues covered before you do a bunch of work.

 

If you want to be done by the end of April, you got two months.  Forget that.  YOU HAVE 61 DAYS! 

Sit down with your dad.  Make a almost daily plan.   Now get busy, and only take time out to take pictures, and post them.

 

Realistically, with two months to get the truck running, I would use an L-engine, rather than trying to do an engine swap, with an engine that did not come in that model of truck.

 

PS.  Do not ignore your school homework!

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The 620 is wider than the 521. The 720 is wider than them, and the D-21 is even wider, so forget the body swap because the tires will be outside the fenders.

 

If the D21 is 2wd it will have the same differential type as the 521 and you can just swap the third member to run the D-21 ratio in it.

 

The '81-'82 Z22 720 intake will work but the '83 and up Z24 720 intake would be better for your D-21 motor. Then just use the weber on it.

 

You can run the D-21 alternator but you may find that it does not properly clear the idler arm below it and the rad return hose above it. Probably better to use the 521's alternator, sad though it is.

 

Get the D-21's down pipe from the manifold. This will make joining it to the existing exhaust much easier.

 

Get the D-21 rad just in case it will fit the 521. I think it will be too wide. As the 521 and the 510 use more or less the same rad, the VW Rabbit rad should work in it also. The top hose will be on the wrong side but it is an improvement over the stock one.

 

Get the D21 throttle cable it has to reach a couple of feet further to the carb than the one to the L16.

 

Battery might not clear the carb as the 521's fenders are so wide.

 

The 521's speedometer cable should fit the D-21's transmission. You will have to re route it down from the fire wall over the top of the transmission to the rear passenger side. I used a short 4 speed one just like the 521 onto a long 5 speed on the opposite side and it can be done.

 

The 521 drive shaft will likely need some amount of shortening. The drive shaft is bolted onto the 521's output spline which has a flange on it. Separate them and if you look at the transmission you will see a large nut holding the spline to the transmission. Remove the nut and the spline slides out of the transmission. The hole the nut covered must be sealed or transmission oil will leak out. Get a 40mm core or engine frost plug and sealer and pound it into the end of the spline. This spline will fit the D-21 transmission. Shorten the driveshaft as usual.

 

The shifter cover plate on the floor may need to be repositioned to fit the new shifter location?

 

The Z24 has no provision for a mechanical fuel pump so simply get a 3PSI electric pump. Avoid anything higher as webers don't like anything above 4PSI. The Z24 runs a return line from the carb to the tank. You don't have this on the 521. It should run ok without it connected.

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Thank you everyone for your ell and I will most likely be posting pictures and other stuff. The only problem is that the 88 hardbody, is totaled. So the frame is bent and all tort shy. The motor an tranny are mint though, that why we were going to do the swap and since the datsun is a 1970 before 75 it doesn't have to a smogged and no problems with the registration because we aren't going to tell anybody and it will just be paying for registration.. So, it is a difficult thing to explain and I don't have a bunch if money so for 50 bucks to pick up a motor was a killer deal. I'll post pictures today. A little later. Thank you again!

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One thing peculiar to the Z24 motor is blowing the head gasket every 100K. There is a preventative you can do that's in the 720 FSM and I suggest you do this before driving it around. It's easy.

 

Nissan recommends that on a cold motor, you re torque the head bolts every tune up or I would say at least once a year. The procedure is to loosen fully, one bolt, and immediately tighten to the full torque of 60 pounds. Move onto the next in any order you like. Front to back, side to side, whatever you like. This keeps a consistent clamping force on the gasket as it ages. Perhaps do this then temporarily put the valve cover on, warm the motor up and set the valve lash while you have your tools out. Remember COLD motor and one bolt at a time.

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Spend more time researching/reading. This is already answered.

 

 

The 620 is wider than the 521. The 720 is wider than them, and the D-21 is even wider, so forget the body swap because the tires will be outside the fenders.

 

If the D21 is 2wd it will have the same differential type as the 521 and you can just swap the third member to run the D-21 ratio in it.

 

The '81-'82 Z22 720 intake will work but the '83 and up Z24 720 intake would be better for your D-21 motor. Then just use the weber on it.

 

You can run the D-21 alternator but you may find that it does not properly clear the idler arm below it and the rad return hose above it. Probably better to use the 521's alternator, sad though it is.

 

Get the D-21's down pipe from the manifold. This will make joining it to the existing exhaust much easier.

 

Get the D-21 rad just in case it will fit the 521. I think it will be too wide. As the 521 and the 510 use more or less the same rad, the VW Rabbit rad should work in it also. The top hose will be on the wrong side but it is an improvement over the stock one.

 

Get the D21 throttle cable it has to reach a couple of feet further to the carb than the one to the L16.

 

Battery might not clear the carb as the 521's fenders are so wide.

 

The 521's speedometer cable should fit the D-21's transmission. You will have to re route it down from the fire wall over the top of the transmission to the rear passenger side. I used a short 4 speed one just like the 521 onto a long 5 speed on the opposite side and it can be done.

 

The 521 drive shaft will likely need some amount of shortening. The drive shaft is bolted onto the 521's output spline which has a flange on it. Separate them and if you look at the transmission you will see a large nut holding the spline to the transmission. Remove the nut and the spline slides out of the transmission. The hole the nut covered must be sealed or transmission oil will leak out. Get a 40mm core or engine frost plug and sealer and pound it into the end of the spline. This spline will fit the D-21 transmission. Shorten the driveshaft as usual.

 

The shifter cover plate on the floor may need to be repositioned to fit the new shifter location?

 

The Z24 has no provision for a mechanical fuel pump so simply get a 3PSI electric pump. Avoid anything higher as webers don't like anything above 4PSI. The Z24 runs a return line from the carb to the tank. You don't have this on the 521. It should run ok without it connected.

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  • 3 weeks later...

Sorry I haven't gotten any pictures posted yet, I'm trying to but it won't let me post them off my iPhone. So I have to download them to my computer, then upload them but we just got the L16 pulled yesterday so we are going to start purchasing parts we need now. Thanks for the help.

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  • 3 weeks later...

Hey guys so I am running in to multiple problems. The front of the oil pan is on top of the steerin component and we have to make motor mounts that a 1/2 inch to an inch thicker or put a spacer in between the old mounts. Any opinions?

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Drill new holes lower down on the left and right engine brackets. You know, the things between the rubber engine isolator and the side of the block. This will position the motor higher but check hood clearance the Z24 block is 4cm or 1.5" taller than an L16 block. The head and valve cover may be thinner than an L series though and it may fit.

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We ended up okieriggin' some spacers because the way that datzen mike said we should try did not work! So we are going to try these spacers we made and if that works I will make sure to keep up to date with everything. I am planning on putting a five speed in, but we only have a four speed right now, the year of truck the motor and tranny came with didn't add up to the repair manuals parts. Typically it comes with a 2.4L Z24I. The fuel injected although this motor came as carbureted, and a four speed although it should have been stock with a 5 speed. So there was obviously a lot of things change to the donor trucks motor and tranny but I am trying to save as much money as possible to get it going the right way. I'll keep everyone updated.

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How about put another L16 in for cheap= (you dont have much money anyways) and maybe a day worth of labor and call it good.

 

 

I see people think since they bought another rig for 50$ thinking its going to save them money only to spend more money and rig isnt done or worth less.

 

 

guy a few months ago on here Tawney or something like that .

His L156 wasnt idleing. pulled motor and never heard from again.

No idle is a simple fix but he made it harder thinking of doing a KA swap.

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  • 3 weeks later...

Alright guys, so I have made the motor almost fit perfectly but we are running into a few problems won the steering. We had to eliminate the crossmember from the torreon bars and took the tie rod out it get the motor in the engine compartment, but now we put the tie rod back in and the oil pan hit the tie rod still. We swapped the oil pickup from the L16 and te oil pan from the L16 onto the Z24. And it fits a little better, although we are going to raise the motor a couple of more inches to get the clearance on the tie rod. It has been a real pain in the a** but it is almost there. Still can't figure out how to upload photos from y iPhone to here though. Oh well, I'll get pictures up soon from a computer.

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The Z24 engine brackets should work.

 

The tag in the engine compartment should say z24 if carb and Z24i if throttle body injection.

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So like I said before guys, this Z24 has a lot of work into it. It had a brand new camshaft and crankshaft. We swapped out the oil pickup from the L16 an the oil pan from the L16 to clear the tie rod. We are going to make a new crossmember for the Tortion bars as I said before. The transmission is not bolting right up now but we did get the motor to bolt up by using the Z24 mount on the passenger side of the 70 datsun and the L16's driver side mount on the driver side of the datsun it self. I am for sure uploading pictures today around 5:30 or 6. You guys will see what is going on hopefully, it's confusing us too ( as in me and my father)..

 

My father has been a mechanic all of his life and has done plenty of motor swaps but cosidering it isn't a Chevy it is screwing with him a lot also. Thank you for your continued support and it has helped a lot. I'm not used to doin any work on Nissans that's why I am not as knowledgable about this swap, and I'm not giving up on the Z24 in this truck. It'll be a project for sure but try to keep patience wth me as I am only 18 and haven't had much experience with doing motor swaps. Thanks guys.

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I put a Z20 5speed in my 1970 521 back in the late 80's.  It was a chore to say the least.  ended up doing a 3" body lift to clear the Weber.

 

Contact Pierce Manifolds for the adapter for the Weber to the Z24 manifold.  You will need to source a 720 wiring harness and be sure to get the coils for the 8 tower distributor. Remove the wiring not needed for the extra headlights.

 

If you read my 66 520 build thread (link below in my signature) it will explain how I adapted the 720 harness to the the 520/521 instrument cluster.   You will have to adapt the 720 harness to your 521 switches for the ignition, wipers, heater, turn signals, and flashers. I would keep the the 720 fuse block and relays.  Basically you would replace the 521 harness with the 720.  get an 81 to 83 720 harness as they have less emissions and I believe the tail lights are wired the same as the the 521.  In my 66 520 build I used a 1980 harness because I used the L20B the only requires 1 coil.

 

Shortening the trans mount is easy. measure and cut accordingly.  Get a five speed if you can.

 

TransMountMod.jpg

 

Get it running and safe to drive then concentrate on all the little things.

 

If you have any questions please ask and I will try to help you answer them to the best of my abilities.

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