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[Slick68]

I just picked up this 86 720 today. It has some issues that need to be diagnosed. It will be a truck for my son, who just turned 13, so we have plenty of time to fix it. It may just need the carb rebuilt, but the PO is afraid it has jumped time. Future plans are lowered ride height, 15 or 17" wheels/tires, better paint, better seats, 5 speed swap, possibly an engine swap. I'll get more photos over the weekend.

 

http://i221.photobucket.com/albums/dd111/Slick68/86%20Nissan%20720/20151231_153718_zpshkjxtrpo.jpg

[datzenmike]

 

Hi Slick and welcome to Ratsun ... again.

 

Pretty sure the chain can't jump a tooth so don't worry about that. The Z24 engine is notorious for blowing the head gaskets every 100K (this is from lack of re-torqueing the head bolts once a year, how hard it that?) Anyway well have you do a few things to check this out and provide suggestions for fixing this. It's good to have some time to get this going properly for your son. I imagine he'll be involved? One other thing... the 4 speed was dropped and only 5 speeds were used after October '82 so your may be a 5 speed with a sloppy gear shift or someone replaced it with a 4 speed.

 

I suggest you go online and look for an '86 Nissan FSM (Factory Service Manual) so you and your son can figure out things for yourselves. New about $80 from Nissan but $20 online would be good. Pays for itself every time you open it up.

[datzenmike]

Ahhh I see from another forum that it's an automatic.

 

If you should find the head gasket is blown DO NOT remove the cam sprocket without first finding out what's needed to block the timing chain tensioner from falling out. Noobs do this, and it's a days extra work to fix added to a simple gasket change.

[Slick68]

Thanks for the info datzenmike. Yes, my son will be involved with the project. He's been wanting it for several months now. He's always helped me in the garage with my projects, and is very knowledgeable about cars/trucks. He doesn't know we even have it yet, but since he's been interested in it, he's been researching wheels, seats, paint colors, etc. I'm hoping to reveal the truck to him either tomorrow or Monday. I'm interested to see his reaction, then which direction he wants to go with it. I know for a fact he wants to build an autocross vehicle. He found out the SCCA has a Jr. class that starts at age 13, so he'll be stoked about it if he can get it running good enough for that.

 

As for me, I'm not new to working on/building cars, but my knowledge is mostly in domestic cars/trucks. I currently have a 68 Chevy C10 truck with an LS1 swap, and we own an 88 Mustang convertible. I'm new to imports, so it'll be a learning curve for both of us. 

[Slick68]

Some better pics. I've not had time to work on it any this week. I've charged the battery, and I'll pick up some oil and filter this evening to change it out and inspect for metal in the old oil before trying to start it. I'll also pick up some gas to put in it. Looks like the tank is empty.

 

[Slick68]

I also need to pick up some sort of air cleaner.

[datzenmike]

Not a fram filter. Get a NAPA Gold or WIX.

Chevron Delo 400 or Shel Rotella T in 15W40. Both are a light diesel oil with high levels of ZDDP.

[Charlie69]

Welcome!  Good looking truck.  Takes a lot of parts to swap to a 5 speed.  I would consider a Weber for carb swap.

[Slick68]

Not a fram filter. Get a NAPA Gold or WIX.

Chevron Delo 400 or Shel Rotella T in 15W40. Both are a light diesel oil with high levels of ZDDP.

 

I never run Fram filters! I run Napa Gold on everything I own. Previous owner said the last time they had the engine running, it had a knock and it rattled. For now, I'll just get some cheap oil and filter to get it running and see what's going on. If it's all good, I'll run good oil and a good filter. I forgot out the Rotella T oil. I'll probably run it when we get it going.

[Slick68]

OK, I was able to get the engine fired up on Saturday. No major knocks or rattles, but it does have a pecking sound when given throttle quickly, then goes away. I charged the battery before trying, but it constantly acted like the battery was weak(which it could be), as it didn't want to turn over easily. The problem was it wasn't consistent. Sometimes, it would turn over easy, then slow down, then  quick again. Any of my dealings with other engines(mostly V8s) leads me to think this may be a timing issue. I can't get it to idle either, which may be another indication to timing being off. 

 

So, the question is, where should the initial timing be set, and what's a good way to get the timing close without it running?

[84720FourWheel]

Should be 3-5 degrees btdc. Crank it over with a ratchet till roughly 5 degrees on the harmonic balance, then rotate the base of the dizzy to cyl 1?

 

Check the cable connection at the starter. My po left the nut loose and it would crank over like that.

 

Idle is probably vacuum lines. They get fiddled with and put on wrong. Looks like there was quite a few missing.

 

Make sure the plug wires are on correctly. I've seen that happen on these and the old dual spark rangers.

[Slick68]

Should be 3-5 degrees btdc. Crank it over with a ratchet till roughly 5 degrees on the harmonic balance, then rotate the base of the dizzy to cyl 1?

 

Check the cable connection at the starter. My po left the nut loose and it would crank over like that.

 

Idle is probably vacuum lines. They get fiddled with and put on wrong. Looks like there was quite a few missing.

 

Make sure the plug wires are on correctly. I've seen that happen on these and the old dual spark rangers.

I'll give those things a try. Yes, lots of vacuum lines missing. I don't even have an air cleaner with it. I'll have to pick something up for it if/when I can get it running. I put a different battery from another vehicle in it today. It stared after a few turns, and ran as long as I kept giving it throttle. I tried to let it off, and it died and couldn't get it to start again. It would try while pumping the throttle, but just wouldn't get there. If I gave it full throttle it would almost start, puff air back out of the carb, then stall when trying to start. It's almost as if the cylinders are vacuum locking. Any ideas?

 

The carb had fuel all around the base, from either flooding or bad gaskets. Would it be easier to replace with a Weber carb or rebuild the stock one?

 

Another question. All the parts store chains and even RockAuto have the 86 720 having an EFI Z24, but mine is carbureted. Can I just order parts for an 85?

[Rhino13]

Yes parts off an 85 will be the same. It will be 10x easier to switch it to Weber, then you can delete all of the vacuum hoses other than the distributor advance and it'll make it a little peppier. The stock carb has a round plug in with 6 or so wires hooked to it. A Weber obviously won't connect to that, but get the electric choke version and you can hook it into one of the holes on the plug. Just use a voltage meter and find which wire comes on with the ignition and its a single wire to the choke.

[Stoffregen Motorsports]

Welcome to the club...that I'm not even a part of since I don't own a Datsun anymore. But it's a good club even without me...maybe in spite of me.