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720SX project - 84 720 + KA24E from an S13


720SX

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Project 720SX (Nissan 720 + 240SX KA24E)

 

Storytime (skip for updates)

 

(Images are Imgur links below)

 

Here's my 1984 Nissan 720 pickup. I picked it up in Virginia about a month ago on a whim - I had been looking for a relatively clean Toyota pick up of a similar vintage with some sort of drivetrain issues so that it would be cost effective, but then I found this absolute gem on Facebook marketplace for $500. It lived in Virginia with its owner, a 17-year-old high school kid. The motor was apparently knocking, but could run, but it was unable to be started. Curious.

 

My buddies and I made the trek six hours down to Virginia with a U-Haul dolly to pick up this beautiful classic automobile. We asked the owner if the tires on the truck would last us for the drive home and he literally laughed. Thinking we’d be fine, we began our trek back to Lancaster, Pennsylvania, and not 30 minutes in our rear passenger tire on the Nissan exploded. After some drama, we had it replaced with a spare and were on our way.

 

We got home, passed out, and then decided the next thing to do was to remove the old paperweight of an engine. We did try to diagnose it to see if we could get it to turn over at all, but as soon as we started turning the crank, we knew that there was something seriously wrong going on within the motor. With this finding, we began the engine removal process. This was an automatic transmission truck from the factory so I wasn’t really too eager to just swap in a new engine or whatever. Immediately, we began thinking of swap candidates.

 

At first, I wanted to do an SR20DET, but money. Then I was thinking a Honda K-series swap, but time. Finally, I considered some sort of VW TDI (BEW) swap, but time AND money. At this point, I knew in my heart that I was a coward, and finally decided that I should take the easy way out and use another Nissan motor, namely a KA24E out of the 240SX.

 

This swap is supposed to essentially just bolt right up to the original motor mount locations, with the only fabrication work being some modification to the oil pan to make it a little bit more slim in profile. So, armed with extremely limited knowledge, I began my search for the donor engine for my Nissan 720. After a few minutes of searching, I found a single cam motor swap locally. I would be getting a manual transmission, an ECU, an engine harness, the engine, and all the engine accessories for $800. I was excited to go check everything out and the prospect of having essentially a full swap in my hands was very enticing.

 

We drove out to Chambersburg to take a look at all these parts, and the motor checked out on the spot. Seemed like The motor had decent compression (which we tested by putting our thumbs over the spark plug holes), and it turned freely (which is more than the old motor did), so we didn’t bother to do so much as pop the valve cover off or really look at it at all. With everything loaded in the truck we began our trip home.

 

We got home and almost immediately took the motor apart, finding that the motor had been stored without oil, probably upside down, and maybe even in a rainforest for the better part of five years. First off, there was milkshake throughout the motor. Then there was rust from condensation all throughout the motor, it was on the camshaft, crankshaft, rods, rocker arms, basically all over the place. There was also chunks of timing chain guides everywhere. The saving grace is that the bores seem to be in very good shape. So, with dashed hopes of an easy swap, we began working to put this motor back to its former glory, if you can even call a single cam four-cylinder glorious.

 

We wound up finding out that the reason this motor was dead in the first place was that the timing chain guides exploded, leaving the chain to eat away at a coolant passage on the front timing cover. This turned the timing chain into a blender, filling the motor with milkshake, and I guess at this point the owner decided to pull the motor. The motor never interfered or anything, so that’s good.

 

On the old motor, the rod bearing on cylinder 3 was eaten away to the point of being paper thin. We pulled a bent rod.

 

So far, I have ordered the cheapest rebuild kit you can possibly buy for these motors off of eBay. To prepare for the build, we have graciously taken the motor to a local car wash to spray it down with the power washers in the same washbay others use to clean their cars. Additionally, I have treated the motor with a variety of products/techniques to remove rust, including evaporust, electrolysis, and a $10 rotary tool from Harbor freight. At this point, I will probably be more surprised and pissed off if this motor actually ever runs again. I am essentially cleaning off all of the loose rust in different spots on the motor and putting it back together. No machine shop, just a 3 finger hone and some praying. My hopes are not high, but I’ve had a ton of fun so far.

 

Feel free to follow my progress on IG @wrenchingwithgummy

 

Plans

I'll update this over time

 

KA swap

 

Hoping I can get this done in a few months. Most of the parts are ready to go, just need to get the motor built and start trying to shove it in. 

 

Tube front end 

 

The truck was in an accident at some point, which compromised the front end. We plan on fabricating a tube front end for the truck. We will be using OEM-style fenders, grille, and lower valance for the front end unless I find something I like better.

 

Interior

 

It's gutted, and will stay gutted. I got seats from a 2012 VW CC for it for now - hoping to do proper harnesses eventually. Not sure what to do with the rest of the interior for now, but all I'm keeping from stock is the dash. 

 

Body repair + vinyl wrap

 

While it's relatively rust-free, the truck still has some rot around 2 cab mounts and a few small holes in the bed. We will have to weld new metal in here. The truck was also poorly repainted at some point, and so I plan on using vinyl wrap to change the color of the truck. Doing this because we don't have the space, time, or budget for a paint job as good as I want and the truck will be used for drifting so there's no point. 

 

Lowering 

 

4" blocks in the rear for now and drop spindles in the front + torsion bars for now. Plan on going coilover suspension if it makes sense down the road.

 

Turbo

 

Going eBay turbo. Woo.

 

Updates

02.19.2021

 

The KA24E has been cleaned as good as I will get it. The rods are spotless, the crank and block have surface rust that will be inconsequential if I change oil frequently for a couple thousand miles. The valvetrain is a bit rough, but we'll see what we can get away with. I will be rebuilding the motor as soon as I receive the rod wrist pin bushings that the parts company forgot to include. I'm using a 3 finger hone for the bores and figuring out the rest as I go... Will post details when I assemble. I'm simplifying the motor as much as I can for the swap - deleting heat, emissions, and everything that isn't absolutely necessary. 

 

Before I'm ready to swap, I'll need to fix the front timing cover, paint the intake mani+valve cover, fab up the oil pan a good bit, and chop up the front end. The plan is to keep the engine bay as tucked as possible. 

 

Parts I'm going with so far:

 

KA24E motor, trans, ECU, and harness - $800

eBay rebuild kit (pistons, rings, all gaskets, timing kit) - $250

O&J Stage 2 cam - $200

Walbro 255 - $60

Icehouse CAN/AM box - $150

eBay dual core radiator - $110

eBay clutch master/slave - $30

 

So, we're at $1,600 in parts, not including the various tools and consumables I've bought to put the truck together so far. 

 

Truck was $500 (+ $150 for gas and Uhaul), sold some Z24 parts and the cap for around $300. Had to buy a new fender set and grille, plus tube. Call it $2,200 total so far. I would be thrilled to get the truck running for under $3k.

 

Any guidance for the swap is appreciated!

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Rent a ball hone aka 'dingle berry hone.' Does a better job.

 

If just hone and ring then get cast iron rings. They will break in and seal better and faster. The harder chrome rings work best on freshly bored perfectly round and non tapered bores. I don't think a turbo is a good idea but adjust the ring end cap wider to allow for extra heat expansion 

 

Replace the rod and main bearings, specially if a turbo in the future. 

 

$30 for clutch and slave masters??? The dealer price is $99 and $50 for the slave. Good OEM quality is about half that so $75 for both. If the old ones still work use them, don't put $15 pieces of shit parts in.

 

Get it running first before deleting emissions stuff or you'll ...

a/ never get it to start

b/ won't know which part removed was actually necessary for running.

 

]2eDeYe on here sells KA engine brackets that should work on the 720.

 

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On 2/19/2021 at 5:00 PM, datzenmike said:

Rent a ball hone aka 'dingle berry hone.' Does a better job.

 

If just hone and ring then get cast iron rings. They will break in and seal better and faster. The harder chrome rings work best on freshly bored perfectly round and non tapered bores. I don't think a turbo is a good idea but adjust the ring end cap wider to allow for extra heat expansion 

 

Replace the rod and main bearings, specially if a turbo in the future. 

 

$30 for clutch and slave masters??? The dealer price is $99 and $50 for the slave. Good OEM quality is about half that so $75 for both. If the old ones still work use them, don't put $15 pieces of shit parts in.

 

Get it running first before deleting emissions stuff or you'll ...

a/ never get it to start

b/ won't know which part removed was actually necessary for running.

 

]2eDeYe on here sells KA engine brackets that should work on the 720.

 

Hey, thanks for the input, really appreciate it. I'll see if I can find a ball hone for rent at one of the local auto parts stores, but everything I've seen has indicated that a three finger hone will do fine for me on this one. Can't hurt to try the ball hone though. 

 

I will just be using the rings that came with my rebuild set - they may very well be cast iron, I haven't pulled them out of the packaging to check. The kit I got came with new rod and crank bearings, so all good there. 

 

Turbo is certainly not a good idea reliability-wise. I plan on swapping the engine in with just the stage 2 cam/intake/exhaust for now, then a lot needs to happen before I start thinking about turbo - namely drop spindles, rust repair + vinyl wrapping the truck, tube front end, potentially a 4 link setup in the rear, and plenty of other stuff such as mounting my seats in the interior and updating bushings, brakes, etc. Turbo won't come for awhile; I plan on riding out the rebuild for a couple thousand miles before going forced induction so that I can get a feel for how good my rebuild will be. If it's low compression/burning oil etc. I obviously won't bolt a turbo to it!

 

The clutch and slave are nothing special to look at, but should work fine. I can't use the OEM parts because the truck had an automatic transmission from the factory. Someone's gotta try the cheap stuff! I'll keep you posted on whether it winds up working for me or not.

 

I do think I have a pretty good idea of what I do and don't need for the motor to start, but I do appreciate the advice. I may wind up putting the motor in with the lines set up as it came from the factory. 

 

If by engine brackets you mean motor mounts, I got that part covered - we weld!

 

Thanks again for the reply.

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On 2/20/2021 at 1:48 AM, Lockleaf said:

There is a how to on this swap on here.  I think it was bottomwatcher who wrote it.

 

I'll have to look up his thread. I've been chatting with @Crytek89 on Facebook since I'm using his write up to help with my swap. Thanks for the tip.

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02.22.21

 

This weekend was less about the engine swap and more about restoring/repairing the 720 itself. Reason being that I'm still waiting on my wrist pin bushings on the rod end (the bushings have pretty serious wear, otherwise I'd run them) so I don't want to assemble the bottom end quite yet. Even then, there's plenty to be done with the intake manifold, valve cover, head, accessories, etc. before we can really start chugging along with the rebuild and mounting the motor.

 

Just to keep this current, here's a pic of what the engine bay looks like at the moment. If you have a keen eye, you'll see the front end is compromised, which is why I'm doing the tube front end. 

 

As I said before, we did some work to the body. My truck is an '84, and has one of those beds that are very prone to disintegrating, especially on the lower seam. Fortunately, being a southern truck, the rust is fairly limited (relative to these trucks) and certainly fixable. The most hateful rust in the truck is around the wheel well seams - that pic should give you a pretty good idea of what we're dealing with. The wheel wells themselves are pretty bad, with the rust on one seem extending to the passenger bedside. This is going to be a drift truck, so I don't care about a show-quality repair, but I wanted to at least slow the rate in which this truck will rust. So, we cut, sanded, welded, and are left with this result. I still need to grind it down and add body filler, but I'm really happy with the turnout. There's minimal warping on the bedside and the repair is strong. Not bad.

 

We have our work cut out for us:

 

Exhibit A

Exhibit B

Exhibit C

 

But we have time, patience, and raw materials to get it done. The worst of it in my mind was the bedside - I only really care about the aesthetics of the bedside repair, everything else is sort of a bonus. The spot welds on the wheel wells must have failed over time, which created this weird dimple effect on the bedsides, so I'm glad to be repairing it all at once.

 

It looks like something on the driver bedside had been repaired before, there were these weird hook looking things hanging off of the inner bedside. Should be very fun to fix.

 

All this has me thinking of running no wheel wells, or some sort of exo-cage on the wheel wells. Not sure yet what I want to do.

 

Additionally, I prepped the valve cover for powdercoating and it looks pretty good

 

Also got the radiator. It's a "G-Plus" that came with a couple of fans, for $110 we'll see how it goes!

 

Walbro came in the mail as well. I'll keep the thread updated.

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On 2/22/2021 at 1:20 PM, datzenmike said:

These bushings in the small end?

Yes!

On 2/22/2021 at 1:20 PM, datzenmike said:

They will need to be reamed to correct size. Are you prepared for this?

Not mentally or emotionally! But I'm sure I'll figure it out.

 

That is - unless you think I can reuse the old ones? They have wear you can feel with your fingernail.

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