1980 720

[minitrucker]

Before I start I searched to the ends of the earth to find an answer for this so if its already on here I apologize in advance.

 

I have a 80 720 with a L20B the trans is slipping and the engine is weak at best. I don't care about speed I just want a reliable truck that will run and drive. Having said that I already had the driveshaft modified for the air ride and don't really want to drop another 500 on that. Do I rebuild the L20B and 3N71 or swap to a Z or KA engine with their respective transmissions (auto preferrably)? If I swap, and this is more something Id like to do, what modifications will need to be done? ie. motor mounts, trans mounts, firewall, etc.

[datzenmike]

Just get another 3N71B from an earlier L series engine 620/A10 (HL510)/S10 (200sx)/610/710.

 

If all you can find is the later Z series 3N71B from the later A10 (HL510) or the S110 (200sx) or the 720 truck, just swap your removable front bell housing case onto it, so it will bolt to your L series engine. The Z series automatic after '82? has a locking torque converter ... you will notice that the flex plate and torque converter are different. If you find one, get these, and bolt to your L20B engine and you will have a locking torque converter three speed automatic.

[petercscherer]

the engine is weak at best. I don't care about speed 

While these two comments contradict each other, I'll assume that you want to ensure that everything mechanical is going to last and be reliable. So I'd recommend running compression tests, pulling your head, installing new head gasket and re-torquing the head-bolts, and rebuilding your fuel system (carb, pump, lines, tank,etc...) These are not very costly and won't require a lot of "down time" where your truck isn't drive-able. 

 

If you're serious about a swap, the best thing to do is google "KA 720 Swap" or whatever engine is your choice. If your interested, I'll include a lot of links that I found throughout my research.

http://community.ratsun.net/topic/30277-z24-to-ka24de-any-write-ups/

http://720world.com/forum/topics/ka24de-into-720?id=2016119%3ATopic%3A82237&page=1#comments

http://www.infamousnissan.com/forum/showthread.php?t=4064

http://www.northwestnissans.com/board/threads/116544-Ka24de-swap-into-Nissan-720-truck-*need-help*

http://forums.nicoclub.com/84-datsun-720-pickup-ka24de-swap-t365060.html

http://forums.nicoclub.com/720-motor-swaps-t398950.html

http://720world.com/forum/topics/2016119:Topic:686?commentId=2016119%3AComment%3A691

http://community.ratsun.net/topic/19011-ka24e-or-de-into-1984-nissan-720/

 

If you're REALLY ambitious, you can learn a lot from nis720's build here:

http://community.ratsun.net/topic/14709-project-against-the-grain-nis720-build/

 

Welcome to Ratsun and I hope this helps!

~Peter

[minitrucker]

What I was trying to say is the engine doesnt run right not that its not enough power. I havent read your links yet but I have searched and all i can find is z to ka swaps or head swaps. Is the l20 and the z or ka have the same mount points? is the length of them with transmissions the same length as the l20b and 3n71 setup? these are things i can't find asnwers to.

 

on a side note how much sould i expect to pay (ballparking of course) to have the trans rebuilt? I got a quote of around $1000 so far. But I only called one place too.

[petercscherer]

Is your current transmission an Automatic or Manual? Regarding mounts, you are going to have to fabricate custom motor mounts and possibly transmission mounts. It's possible that your custom driveshaft will work with the Z24 or KA24 transmissions, but I can't say for sure. As far as I know, L20B transmissions won't directly bolt up to a KA without the proper bellhousing. 

That all being said, you can source a good working KA engine AND transmission for less than the $1,000 quoted for a transmission rebuild. 

What kind of mechanical or fabrication skills do you have? 

~Peter

[minitrucker]

What kind of mechanical or fabrication skills do you have?

 

Mechanical - enough to "probably" pull this swap/rebuild off

fabrication - not really

 

Is your current transmission an Automatic or Manual?

 

Automatic

 

 

Regarding mounts, you are going to have to fabricate custom motor mounts and possibly transmission mounts.

 

Is that for any swap? ka24e ka24de z24 z22?

[Jester]

Wow, you must have caught these guys on a good day. Anyone else and they would have said you were full of shit about not finding anything. There is a TON of info on KA swaps into just about everything, 510,620,720, whatever. 

You did come to a great site with LOTS of info on the subject. And a lot of guys that are willing to share what they know.

 

 

Welcome to Ratsun.   :thumbup:

[petercscherer]

If I recall correctly, the L20B mounts are different from the Z24 mounts, which are different from the KA24 mounts, etc... So motor mounts are a must no matter what, and they aren't a big deal, if you can't weld them yourself, I'm sure there's welding shops there in Tulsa that can work with you to fab some up. My preferred method is to make a prototype from rigid cardboard and get it in the exact shape needed and reverse engineer the metal mount from that piece.

 

If I were you, with the skills you mentioned, I'd go with a Z24 or KA24 with the corresponding transmission. You'll have some expenses to consider with this swap (or any swap for that matter). It's more than just buying the donor engine/transmission, you'll also need:

 

Wiring components and harnesses

Fuel system (including upgrading your tank with a fuel pump/baffles)

You'll need to plan out how what accessories to run(additional costs)

Are you going to be keeping stock gauges or using the donor vehicle's

Cooling system upgrades or modifications

You also may need to rebuild your donor engine ($)

General maintenance costs for your donor drivetrain (belts, hoses, plugs, wires, injectors, etc...)

 

 

Quite a few people here on Ratsun will automatically say that any motor swap should be accompanied by a brake/suspension upgrade to handle the extra weight/power. You mentioned rear air-bags, so I'm not sure what has been already finished there. On that note, I'm surprised Mike didn't request pictures, those will really help our community to problem-solve with you and get you on the right track.

 

~Peter

[petercscherer]

Oh, and since you mentioned that you were having trouble finding articles that show L20B to KA24DE conversions, try searching for "Datsun 620 KA Swap". The 620 has the same engine as your truck and the overall swap ideas are the same.

 

Here's an extensive thread that should point you in the right direction:

http://community.ratsun.net/topic/3811-my-77-kc-620-ka24de-swap/

~Peter

[minitrucker]

Wow, you must have caught these guys on a good day. Anyone else and they would have said you were full of shit about not finding anything. There is a TON of info on KA swaps into just about everything, 510,620,720, whatever. 

You did come to a great site with LOTS of info on the subject. And a lot of guys that are willing to share what they know.

 

 

Welcome to Ratsun.   :thumbup:

 

Thank you for the welcome. You sir are very right there is a lot of info about swapping ka and z in and out of 720 s but from my understanding (and it may be wrong) the 80 was the only year to have the l20 and for that reason I cant find any info on swapping that l20 for another engine. But now typing this i guess i couldv'e looked into a swap to a 620 since they both used the l20. but then my concern on length is still an issue.

 

You mentioned rear air-bags, so I'm not sure what has been already finished there.

 

The whole truck is on air ride not just the rear. What are brake upgrade options?

[minitrucker]

Is there a difference between KA24E and KA24DE? I have found its more common for guys to swap the DE but i did find a fairly useful writeup about the KA24E.

[petercscherer]

Is there a difference between KA24E and KA24DE? I have found its more common for guys to swap the DE but i did find a fairly useful writeup about the KA24E.

 

KA24E is a Single Overhead Cam engine similar to the Z24 but more technologically advanced. The "E" stands for Electronic (fuel injection)

 

KA24DE is a Dual Overhead Cam engine like more modern cars. The "D" stands for Dual and the "E" once again means Electronic (fuel injection)

 

 

 

The whole truck is on air ride not just the rear. What are brake upgrade options?

You can swap your entire front spindles for later model Hardbody spindles for 1983-1987 Nissan trucks, you can then bolt dual piston calipers and vented rotors on these for better stopping power. A common rear brake upgrade is discs off a different brand of vehicle with adapter flanges and adapters. I think the Ratsun user named beebani makes them now....

 

[Edit] Yep, here's a link: http://www.ebay.com/itm/REAR-BRAKE-CONVERSION-FOR-NISSAN-DATSUN-PICKUP-/191531560754?pt=Motors_Car_Truck_Parts_Accessories&hash=item2c982baf32

~Peter

[harlow426@mail.com]

After my recent experience with my 79 280zx.......

ditch the ka idea............go L28 with the matching auto.

Will b a bit of work......but any retrofit is.

I also have an 80720(kc)......if my truck wasn't needed fixed asap I'd rather put the Lsix in rather than with fixing the anemic/poor torque curve L20b.

Go drive a cheap C.L. Z car.......then imagine your truck scootin' like it can! Near identical curb wt......720-79'280zx.

I am sure some will say nay to my idea.......think you could do the swap cheaper than a ka if u shop smart.

[datzenmike]

Mechanical - enough to "probably" pull this swap/rebuild off

fabrication - not really

 

 

Automatic

 

 

 

Is that for any swap? ka24e ka24de z24 z22?

 

 

Better to analize what you have and if you have another motive. Is the L20B really that bad? or are you just wanting to jump into a KA swap? Fixing your L engine is far far easier for someone without much mechanical skills and not interested in doing fast. Then drive it for a while and learn all you can about this swap. Type KA swap into 620 into the search engine... in fact type anything related to what you want to learn about and read. Research is the key to making sound decisions .

[petercscherer]

After my recent experience with my 79 280zx.......

ditch the ka idea............go L28 with the matching auto.

Will b a bit of work......but any retrofit is.

I also have an 80720(kc)......if my truck wasn't needed fixed asap I'd rather put the Lsix in rather than with fixing the anemic/poor torque curve L20b.

Go drive a cheap C.L. Z car.......then imagine your truck scootin' like it can! Near identical curb wt......720-79'280zx.

I am sure some will say nay to my idea.......think you could do the swap cheaper than a ka if u shop smart.

Ever taken a tape measure to both the L28 and your 720 engine bay? You'd need any additional 10" in order to make the L28 fit. I seriously considered doing what you suggested, but when I compared the power/weight ratio and the incredible engine set-back required, I gave up. Keep in mind that the L28 in the 280ZX only makes about 140HP, which is comparable to quite a few of the engine options that the OP is considering. 

~Peter

[minitrucker]

You can swap your entire front spindles for later model Hardbody spindles for 1983-1987 Nissan trucks, you can then bolt dual piston calipers and vented rotors on these for better stopping power.

 

did the hardbody come with dual piston calipers? do they make slotted rotors for the hardbody or am I looking for them to be from another vehicle?

 

Better to analize what you have and if you have another motive. Is the L20B really that bad? or are you just wanting to jump into a KA swap? Fixing your L engine is far far easier for someone without much mechanical skills and not interested in doing fast. Then drive it for a while and learn all you can about this swap. Type KA swap into 620 into the search engine... in fact type anything related to what you want to learn about and read. Research is the key to making sound decisions .

 

I'm starting to see that light. This truck is not a daily driver its actually a lawn ornament until i can get it running, so down time isn't an issue.

 

 

 

While the L20 is out what are some modifications that I should look into? ie. headers (who makes them?), intake swap? (is that a thing on these engines?)

 

Oh and by the way THANK ALL OF YOU so far for the help. I really mean that. As this truck unfolds I'll be back here asking all kinds of questions I'm sure.

[ggzilla]

Why are you planning on taking the engine out? Why not just give it a tune-up and enjoy driving it?

[minitrucker]

Why are you planning on taking the engine out? Why not just give it a tune-up and enjoy driving it?

 

The transmission needs rebuilt. The engine has a problem with not wanting to start after its warmed up. It also like s to die on you for no reason. I have a lot of clean up work to do under the hood and paint the engine as well. Also going to take this opportunity to fix the front suspension (the person who bagged the front of this truck was high on meth) The back looks pretty damn good but the front...tsk tsk.

[datzenmike]

After my recent experience with my 79 280zx.......

ditch the ka idea............go L28 with the matching auto.

Will b a bit of work......but any retrofit is.

I also have an 80720(kc)......if my truck wasn't needed fixed asap I'd rather put the Lsix in rather than with fixing the anemic/poor torque curve L20b.

Go drive a cheap C.L. Z car.......then imagine your truck scootin' like it can! Near identical curb wt......720-79'280zx.

I am sure some will say nay to my idea.......think you could do the swap cheaper than a ka if u shop smart.

 

Terrible thought. The L28 is a boat anchor and the last thing you want is more weight over the front axle. Good in a straight line but only so so good. 

 

 

Why are you planning on taking the engine out? Why not just give it a tune-up and enjoy driving it?

 

Get it running. No one I know was born a runner.They crawled first, then stood up, then learned to walk... and then they learned to run.  You get ahead of yourself and that truck will go down the wrong path and not get turned around.

[ggzilla]

The engine has a problem with not wanting to start after its warmed up. It also like s to die on you for no reason.

Common problems. Removing the engine won't fix those problems.

[ggzilla]

Good on ya.

[minitrucker]

Common problems. Removing the engine won't fix those problems.

 

 

What could be the culprit? What should I look for? When I bought the truck I had an extra starter for it. I took that one and the one in it and had them tested and both were good. Tried with both starters and the same problem still exists.

[Jester]

It is not very often that an ignition coil goes bad, but, sometimes they do. They are filled with oil to keep things cool in there. If your coil is going bad it will not want to start once the rig is warm. Could also be as simple as a loose gasket somewhere. As an engine heats up things expand and allow more air to enter where it is not suppose to be. If this is happening on the intake side, it could be an issue. Lots of possibilities without seeing it. 

 

Lets see some pictures!  Here is how to post them. 

[ggzilla]

Stalling when coming to a stop is most usually caused by a cracked vacuum hose.

 

"Hard to start when warm" has many potential causes. What kind of symptoms are you having?

[Rhino13]

My truck has been having idling issues, and my buddies had a similar issue to yours, dying when warm. We changed all of his vacuum lines, and found a leak in the process, then adjusted the carb and it runs fine now.

Could also be your choke though. They work based on how cold/hot the engine, electronically adjusting idle speed as it warms. Yours could be stuck on causing it to always be choked, meaning once warm it would be too rich to run because the choke restricts airflow causing the engine to idle higher and get warm quicker.

Take your air filter off with your truck fully warm, is the choke plate in the left venturi closed still? If so your choke is stuck closed or needs to be adjusted back. There's plenty of instructional videos on how to do it. I can type it all out if you want me to, but a good reference is Eric the car guy on YouTube, watch his carb rebuild video.