L24 swap into 85 720 2wd

[By tha powa of grey trucks]

Hello, 

Today my z24 has given me reason to rebuild it or replace it. I've been plagued by broken parts that can't be sourced like the vacuum advance so I'm leaning towards swap. I've noticed most people get ka engines but I'd like to make this unique and maybe easier with the L24 from a 240z same year as my truck. I've found one local and it's complete. Are the bell housings different? The look the same in images. Starter and ring gears different? When did they start putting Nissan on the valve covers? Was the datsun 240z ever computerized? I hate the 1 computer in my truck.

[Stoffregen Motorsports]

Interesting choice of swap for sure. To answer your question, no the bellhousing is not the same. The bolt pattern is the same, but the clocking is different. You can easily swap in the correct transmission or swap bellhousings to get the clocking right.

 

But a long six in a pickup may be a tough fit. A V6 would be a better option, and that's coming from a guy who absolutely hates just about every V6 on the planet. I've never met one that sounds right.

[By tha powa of grey trucks]

Thank you for telling me about the bell housing! How bad is the clocking? The warden... Erm I mean fiance has allowed me to get the engine but as much as possible has to be recycled aka trans radiator alternator.

[datzenmike]

Won't fit. The L24 is at the least, 190.4mm or 7.5" longer. So go out and measure, and the fan will be in or in front of your current radiator.

 

The L24 and your Z24 'lean' at different angles. The L24 about 12⁰ to the right of vertical and the Z24 about 6⁰ to the left of vertical, a difference of about 18⁰. If you put a Z24 5 speed onto an L24 the shifter will be over to the right 18⁰ and in the passenger's hip. 

 

The L24 is nice but newer 4 cylinder engines fit and make at least as much power. A KA24E or KA24DE from a D21 Hardbody can easily be converted to a Weber down draft with a n aluminum adapter plate, and an L20B matchbox distributor and drive spindle swapped in to get rid of the CAS.

 

The KA engines will bolt up to your 5 speed.

[By tha powa of grey trucks]

I had concerns about dimensions and shifter placement. The fact that the engines only an hour away and that the bell housing pattern matches makes me still want to try it. Worst case I go full send and make it all fit. Alter the trans crossmember, shifter and cut the radiator forward with electric fans instead of the clutch fan. Also sourcing fuel injection parts would probably throw me over budget compared to carbureted L24

[datzenmike]

Already addressed getting rid of fuel injection on a KA engine from a D21 Hardbody. Put a Weber on an adapter plate and an L20B distributor, even a points distributor will work.

 

 

Look where your crankshaft pulley will be moved 8" forward... right into the cross member running under the radiator. The L24 oil pan will not clear the steering cross rod and the bolt in cross member that supports the front of the torsion bars. I have no idea where the L24 engine mounts are in relation to a 4 cylinder mount on the frame.

 

Just because you have this engine, is the worst rationalization for using it. The best engine swaps are ones that fit. Don't do this, it will end up in the wrecking yard because no one will want it, and too hard to fix what's been done to it.

[By tha powa of grey trucks]

It will be ok. I appreciate your concern and rational input! Believe me when I say most people would have pitched the truck 30 years ago before grampa rebuilt it with 2 other 720's. It's got a solid straight frame and in 2021 I put in the 3rd set of floors so I went with 16ga floors and 14ga mounts this time. Overall it looks like it's in decent shape just not straight. Drives nice stops better than anything in my fleet great heat but not worth a thing because my families cobble work. There is always a solution for whatever obstacle someone will run into on a swap. Wether the radiator is rehomed to the bed or I have to build a crossmember to clock the engine and trans. I'll do whatever I have to, split the difference 9 and 9 degrees notch and bend the shifter graft part of the z24 oil pan on relocate sump reshape lower core support. It will never be a show truck but I truly want to try this. It'll cost me little more than the $750 engine itself and rebuild kit compared to buying a ka rebuilding it too then swapping a $450 webber kit and different distributor. I have the steel tools and now thanks to you and the other members crucial information to make the L24 work in a 720 albeit at its dimensional limits.

[Stoffregen Motorsports]

I say go for it, but please, do it right and finish it. I have grown tired of seeing half finished projects rusting away in side yards or wrecking yards.

[By tha powa of grey trucks]

Thank you and I'm eager to start! The guy is bore scoping it and doing leak down tests on it before I pick it up. Says he's got 4 more L24 and 7 L28 if this ones in poor shape. He was concerned about fitment but believes it's possible with fab work as well. My welds are usually a bit heavy but they never fail me. I think I can reshape the lower core support with serious heavy flat stock and do the same with the crossmember. I hope the accessories and starter all work or I'm gonna be in the dog house with the old lady hahaha

[datzenmike]

If I can't talk you out of it then indeed go for it. Once the L24 is fitted it's no big deal to fit an L28 even. Look for an L series 4 speed, probably they will throw them away. You can swap the front case half onto your 720  speed. Only thing needed is a new 56mm counter bearing to replace the too large 62mm that's on it. Of course if you can find an L series 5 speed then just swap it all in.  

 

The bulge in the L24 oil pan will have to be moved probably to the rear to clear and the pick up tube modified to fit.

 

The front cross member under the radiator can be modified but you can't eliminate it as it adds rigidity to the frame rails.

[bottomwatcher]

Document this in a build thread and prove us wrong. This will be interesting.

[Stoffregen Motorsports]

Have you ever done this kind of work before? There are lots of details to consider before the cutoff wheel gets used.

 

Will you have enough clearance at the front for your accessory drive and radiator fan? If you're pushing forward 8 inches, there may only be room for a pusher fan in front of the radiator, and this may even be in place of the grille. Do you want to see an electric fan where your grille is supposed to go?

 

Can you cheat the motor back a couple or few inches? If this is a 2wd truck, the only issue would be the shifter location. Shifters can be heated and bent to any shape you like, so consider that. Crossmembers and driveshafts can be modified, moved, shortened, etc. And if cutting the firewall, cut out a piece and move it back, then fill in the gap. That's the easy way, but not necessarily the nicest way.

 

I have a 5/8" rule here in my shop. No component should be less than 5/8" away from anything. This is crucial when dealing with moving parts like alternators, power steering pump pulleys, and especially exhaust manifolds and tubing. Any closer than 5/8" on the exhaust, and the heat will melt paint or your feet.

 

To your comment of heavy steel, it's not always wise to combine different thickness of material. Meaning, if you cut out a section of sheetmetal, filling it in with flat stock can have its problems. The two metals won't have the same flexibility and cracks can develop over time. Trial and error is the only way to find this out.

 

I still want you to try. It could be a cool truck when finished.

[By tha powa of grey trucks]

I have done this type of fab work before. Not necessarily engine fitment but a lot of structural rust repair and friends projects over the years. Im sure I can make the alterations safely.

 

I just looked at the z24 plugs rockers coolant and oil. Decent looking plugs and valve lash is in spec oil and coolant look good. Still runs but its down at least 1 cylinder but only knocks off idle. Not sure what's happened inside but doesn't matter now.

 

The Only accessories on the front will be the water pump and alternator, no fan no power steering. I've decided the radiator is going to have to live in the bed with electric fans. I'll enjoy seeing the rotating assembly from the front, it should land right behind the grille. 

 

There's roughly 1 3/4 inch behind the block where egr tubes are. If you measure 8 inches from the head of my z24 forward it lands just half way through the radiator. Leaves 1 1/2 inch clearance for head from upper core support. The water pump pulley on my z24 protrudes 2 and 3/4-7/8 hard to measure that assembled. Assuming the L24 pump and pulley is similar it will sit safely behind the grill with roughly 2 inches to spare . It looks that the alternator will fit in the original opening for the radiator as well. The crank pulley will just barely go through the top of the lower valance but still sit behind the front bumper. Oil pump will be my biggest problem so far. I'll have to experiment with clocking and mount height to mitigate how much needs cut out for that.

 

And thanks again for the wealth of knowledge! Absolutely outstanding help!

[By tha powa of grey trucks]

Picking up the L24 and a 4 speed this afternoon. Engine might be from a 71 240z judging by head/block combo E88 and P30. Not sure how to post photos here from my phone. I'll document it on YouTube and post the account here once videos are up if that interests anyone.

[Stoffregen Motorsports]

I believe you need to have a minimum amount of posts before you can add pics.

[By tha powa of grey trucks]

That's fair. I'll just update on here till I get enough recorded to post on YouTube.

 

  Which by the way the engine and trans is home and stripped as far as I can go without the seal kit. I couldn't be happier with it's overall condition. It leaks absolutely no oil. Im ordering a distributor. The very first and last exhaust studs are snapped off in the head. Aside from that everything's looking good. 

 

  It came with the flat top hitachi carbs. For some reason the little plunger rods are through the plastic caps on top of them. Is that normal? Ones pulled way out and bent. Could be straightened though. I'll put a kit in em but I feel like those plunger rods or whatever they are shouldn't be pulled out and bent.

 

Next couple days off I'll push the truck in the drive and pull the engine.

[datzenmike]

Those '74 L26 flattop SUs (aka boat anchors) were considered the worst. Early SU carburetors were not very emission friendly so Nissan changed to those flattop SUs for the '74 model year to try and need the standads, but they were incredibly complex and difficult to tune. Mechanics hated them and many refused to work on them. Owners often threw them away and put the earlier round top ones on. Not at all cheap today.

 

With a really small 4bbl?

 

https://www.ebay.com/itm/355470126880?itmmeta=01HTXFK19AG5N7KAKFEF7NTET9&hash=item52c3abaf20:g:yaEAAOSwGNVlz-FW

 

Arizona Z car

 

[By tha powa of grey trucks]

That'd be an ideal solution. I'll still do my best to bring these hitachis back to life but I will buy the adapter as soon as possible.

[datzenmike]

I've heard dozens and dozens of remarks against the infamous Z car flattops and only one saying they were extremely good performers.  I think this is after they are 'de-smogged' and some things removed and disconnected. Z Therapy who rebuilds the 240z carburetors says to just throw them away.

[ElliotV]

3 hours ago, By tha powa of grey trucks said:

That's fair. I'll just update on here till I get enough recorded to post on YouTube.

 

  Which by the way the engine and trans is home and stripped as far as I can go without the seal kit. I couldn't be happier with it's overall condition. It leaks absolutely no oil. Im ordering a distributor. The very first and last exhaust studs are snapped off in the head. Aside from that everything's looking good. 

 

  It came with the flat top hitachi carbs. For some reason the little plunger rods are through the plastic caps on top of them. Is that normal? Ones pulled way out and bent. Could be straightened though. I'll put a kit in em but I feel like those plunger rods or whatever they are shouldn't be pulled out and bent.

 

Next couple days off I'll push the truck in the drive and pull the engine.

I'm curious to see where this project goes. The parts truck I picked up recently is pretty much dedicated to be a 4x4 toy/project I wonder if a guy would be able to make the i6 work with a custom oil pan and pickup tube. Definitely would be weird and cool two of the most important factors for a project in my opinion.

[Skib]

1 hour ago, datzenmike said:

I've heard dozens and dozens of remarks against the infamous Z car flattops and only one saying they were extremely good performers.  I think this is after they are 'de-smogged' and some things removed and disconnected. Z Therapy who rebuilds the 240z carburetors says to just throw them away.

 

 

Flat tops are not worth putting any effort into lol to the bin with them.

 

Swapping the L24 isnt worth the effort either.... for the whopping 80-100hp.

[datzenmike]

Their rated 150 hp was gross back then also and not net.

[By tha powa of grey trucks]

A truck with a running engine is worth a lot more than a truck with 1 or 2 hurt wrist pins. 

Don't worry skib It'll get built either way. I have a family obligation to keep grampas truck on the road. This 720 served my family the last 40 years and it'll continue to do so.

[Stoffregen Motorsports]

If you are going to use the truck for truck things, and maybe even a little off-roading, I would also ditch the SUs. The nice thing about that 4 bbl conversion is the carb. It has an accelerator pump. SUs do not. Cold starts with an accel pump are easier.

 

That said, I've never liked the dual DGV conversions for Z cars. For some reason they always dieseled a lot on shut down. I think it was because of the shape of the adapters. They had a big pee trap shape and fuel would puddle in the bottom.

[By tha powa of grey trucks]

Trucks engine is all stripped down just sitting on the crossmember. I'll get the neighbors lift out tomorrow and the dirtiest part of the job is done! Time to start fitment and disassemble the 4 speed.