My 1981 720 4x4 KC questions

[swaffles44]

Hello Ratsun!!

 

 

I'm new to this site and this is my first post. So here's the story on my datsun..

 

 

I have a 1981 King Cab 4x4 i picked up two years ago from my great uncle who passed away at the time. It is a two owner (including myself) truck that my uncle drove off the showroom floor in 81 and kept pretty damn good care of. It's got 185,000, 7,000 of which i have put on. I even have the original owners manual from the factory and all of his oil change reciepts.. Since i've owned i've done all the usual old truck tuneup stuff like new plugs and wires, distributor, belts, etc.. but other than that have kept it entirely stock.

 

 

 

 

 

Now however I want to do some work on it. Nothing major or crazy, but i do want to get some more power out of the engine, not a whole lot, just enough so that it isn't a complete dog anymore..The engine is a z22 by the way. I also plan on putting some bigger and more aggressive tires on it as the ones it has are wee bit dorky...

 

Anyway here's a couple of questions I have..As far as adding some horse power goes it seems the way im headed is getting a new carb and at least cat back exhaust at 2'..What sort of carb would I want to be looking at for my z22 engine? Also by adding a bigger carb will i need to replace any internal parts on the engine as it's so old? I dont know a whole lot about engines but have a mechanic who will be helping me work on the engine..RReally any suggestions about what I could do to get more power would be helpful.

 

 

 

Well I'm sure there will be more questions as I think of them, but for now farewell and thanks!

[datzenmike]

That is a really nice example of an '81. Welcome to ratsun.

 

You should fill out your profile with at least the state you are in. You may be limited in what you can do because of emission testing.

 

If the exhaust is in good working order just leave it. The expense isn't worth it and there are no real gains that way. If allowed, you could cut the cat out and replace with straight pipe. No gains but might toughen the sound a bit. A new Weber 32/36 would be better at the cost of a few MPG. You won't need to replace the motor or anything on it if you do. Be sure to spend the money and get a genuine Weber replacement kit. It will have everything needed to convert it. You have the 4.375 rear end and going to lower gears will be difficult. If changing the tires, going taller will hurt performance, so try to just go wider. Steer away from after market ignition systems, save the money, the stock one is excellent as is.

[swaffles44]

That is a really nice example of an '81. Welcome to ratsun.

 

You should fill out your profile with at least the state you are in. You may be limited in what you can do because of emission testing.

 

If the exhaust is in good working order just leave it. The expense isn't worth it and there are no real gains that way. If allowed, you could cut the cat out and replace with straight pipe. No gains but might toughen the sound a bit. A new Weber 32/36 would be better at the cost of a few MPG. You won't need to replace the motor or anything on it if you do. Be sure to spend the money and get a genuine Weber replacement kit. It will have everything needed to convert it. You have the 4.375 rear end and going to lower gears will be difficult. If changing the tires, going taller will hurt performance, so try to just go wider. Steer away from after market ignition systems, save the money, the stock one is excellent as is.

 

 

Thanks. Well the exhaust is slowlly rusting out, and has a substantial hole in the muffler. I also had to patch a section of fit that just broke apart. However seeing that I live in washington and drive a 30 year old car, i never have to have emission tested again, so i'm pretty free to make wahtever modifications I want. Thanks for the advice, i'll keep it in mind as I go along

[swaffles44]

Some more pics of my datsun

 

 

 

[Skulptr]

Another washington man!.where are you at?

 

here's a way to help with the exhaust. Delete the cat, use chambered or glass pack mufflers, don't go above 2" or you'll lose your back pressure.

 

I put a weber 32/36 dgev on mine, deleted anything to do with emissions, including the egr pipe off the manifold. You should be able to full up an apple box with the old carb and emissions stuff you pull off.

 

 

Welcome to ratsun. I've found over a dozen guys here in washington alone that are active, I'm trying to setup a washington meet thats central for everyone. Never had a washingtonian meet before

[datzenmike]

If that truck has been kept in good shape it's way easier to maintain the emission system than to start ripping stuff out and have it run poorly. A properly functioning emission system has almost no effect on full throttle performance.

 

The carb for the Z22 is adequate but a slightly larger 32/36 will give some full throttle and mid range gains in power.

 

 

Yes, if the exhaust is toast have a new one bent with 2" pipe straight back to the muffler. This is the size on the Z24 motors, maybe on the Z22 as well? The 720 uses a pretty small muffler so maybe source something larger from a V8? passenger car? whatever. And run a slightly smaller outlet pipe, maybe 1 3/4"? If you want more noise a turbo muffler maybe, but the sound quickly becomes tiring and your $2,300 stereo system will sound like a $150 one.

[swaffles44]

I'm over on the westside, seattle tacoma area..

 

ya the new weber carb is probably what I'm gonna start with... Will that give me any noticeable power gains? ya the exhaust is 2'' back to the cat but then it's something like inch and quarter from there out? I'm not entirely sure.. I think the plan is to tak the cat out and do 2'' all the way out, with a new muffler of some sort, haven't got it figured out yet.

 

 

I hadn't planned on pulling out any emission stuff as it all seems to functioning perfectly..does the emissions stuff really have a negative effect on power? and if so is it even worth the trouble of taking it out, just to have my truck not running? Also forgot to mention this is my daily driver..

[datzenmike]

If that truck has been kept in good shape it's way easier to maintain the emission system than to start ripping stuff out and have it run poorly. A properly functioning emission system has almost no effect on full throttle performance.

 

Any gains that people report are from removing a poorly maintained system full of mixed up and leaking hoses and broken sensors. Removing them removes any problems and the motor runs better. Pulling everything off a perfectly good system is a waste of time and you could add a problem doing this.

 

Ignorance of how the NAPS system works leads people to think they are being cheated of some magical hidden horse power but in reality you aren't. For example the EGR system does not even operate at idle or full throttle so how does that affect performance? The fuel shut off system cuts off the idle fuel when decelerating and would normally be sucked out the exhaust and actually improves gas mileage. The PCV valve removes blow by fumes from the crankcase to help keep the oil clean. The carbon canister collects gas fumes from the carb and tank and sends back to the carb when running. Dual plugs allow leaner mixtures to be run to increase mileage. The warm air from the exhaust manifold improves cold weather drive ability. On and on.

 

Removing them is purely a cosmetic thing.

[swaffles44]

So it turns out my old carb, which we had just rebuilt a few months ago went bad again. So i ended up puting a 32/36 dgev weber on, and it seems to be working beautifully. Also had to put a new air cleaner on it.

Had to remove some vaccuum stuff, and had to adjust some plates and what not, but other than that it pretty much just bolted right on. Gave it a nicer, throatier sound too, especially when the secondaries kick in :thumbup:

 

Next up im going to rebuild the exhaust... pobbly gonna cut out the cat and do a new 2" straight pipe back to the muffler... nosure yet though, as my exhaust manifold doesn't look to be in great shape.. heard replacing it is costly and risky though... so we'll see

[poor-mans-720]

dude, whats up?? Im over in puyallup!! great deal that we are so close... exhaust manifolds, arent that bad. I had a huge crack in mine. welder, said it would be like $40-50 to weld up, i think... was a while ago. Or just pick one up at a J/Y. I got mine at a little yard over here in puyallup for, about $25. And it came off a Z20. fits great, works great. much better shape, then my last one was in.

Also that is a great looking truck, and b-e-a-utiful weber... super jelly... i been saving for one. busy lifting mine... if ya need some help with the exhaust, hit me up. i have a welder. not going to say i am the best. but if your any good. lol, maybe we can meet up. it was kinda a PITA to do on mine. pulled the exhaust through the bottom. but with the right amount of extensions, (14), you can get to the back bolt easyly. let me know if your interested in finding a JY exhaust manny. I live close to the 128th street JY. they have a couple 720's back there...

[OneFreakyMF]

BEAUTIFUL RIG!!

 

To think that my rig use to look like that is almost mind boggling!! I did the emissions delete thing when I had a 38 Weber dropped in my lap. If I would have paid for the Weber I probably would be upset with its perfomance but being that it was free I'm Ok with it. I think that it is just a lil to much carb for the lil four popper! I'm out in Bremerton if you are out this way and need a hand!!

[poopypants720]

I don't know the prices in washington, but while pulling a cab strap off a truck some other guy snagged the exhaust manifold, they only charged him 35 bucks with the egr and down pipe still hanging on!

[swaffles44]

Ya fortunately I work at a landscape company that has afull service shop, so welding shouldn't be a probelm lol. Thanks! ya im pretty pleased with the way the new carb looks. Engine just looks cleaner now without that big ass air cleaner assembly on it.

 

got a question though, my seats are pretty shot, seeing as they are factory originals from 81 lol. anyone know what seats will fit in witht the least amount of work? have heard that mazda 626 seats bolt right in.. also heard that 300zx manual seats will fit pretty easily..

[poopypants720]

http://community.ratsun.net/topic/42162-compatable-seat-swap/

 

;)

[OneFreakyMF]

My seats are out of a cherokee and were NOTHING even close to bolt on. My lil rig is a testament to what you can do with a lil welder and some imagination!! However, there is a HUGE difference between your truck and what I started with! You've got a gem there. I remember looking through that link when I yanked my old seats out but then I had the cherokee seats dropped in my lap. I can afford free so I made them work! Good luck man!!

[nissanprerunnerdavid]

weber is a good idea for sure. for the exhaust some people say a header doesnt do much but the header on mine was day and night. actually just the new exhaust system. the combination is incredible and i sugest getting a header and replacing all the exhaust for everyone. best thing i did besides rebuild the whole engine ;)

[Zlich]

With my 81 I undid the bolts from the header and pulled my whole stock exhaust system out and have 2' pipe to a glass pack that goes from 2' to 6' and its loud AF the neighbor calls me the public nuisance. have all the back pressure I need for the most part. when I coast down hills it does a pop pop sound but other than that it sounds nice. I was told just about any seats from a nissan will fit but I have some pathfinder seats in my truck that are just held in place with some self tapping screws.

[Gradyfest]

Awesome truck! Its loaded. I love the optional sport stripes and fender flares! Your uncle had great taste. I know I'm digging up a couple year old thread, but did you ever replace the wheels? I'm shopping hard for the OEM rims with center caps that are on your truck in the photos. Hope you can help!