My 1985 Nissan 720

[_chiefjt]

I have some questions about my 720 I bought recently for $850. I'm only 16 and it's my first car so yeah, just need some help. It's a 1985 Nissan 720 Napz, 2WD.

 

1. What's the best high performance exaughst set up for my z24? (A full exaughst set up)

 

2. I don't know what my rear end differential is but my plate says HF37, I think it's a 3:7?

 

That's about all I can think of right now, I'll ask more when I come across anything.

 

Thanks

[ggzilla]

1. Use the stock exhaust manifold, and have a custom shop fit a full-mandrel-bend stainless 2" exhaust the whole way back. The exhaust should give you a 2-3 HP increase over a stock 720.

 

2. HF37 is indeed 3.7 ratio. Fitting a 4.11 will increase you acceleration enormously. It will feel like 40 more HP. The downside is that fuel economy will go down on the highway.

[nis720]

I would recommend some Doug Thorley headers and a full 2-1/4" exhaust. The piping would have to be custom made because of the way the thorley headers dump further back compared to stock.

 

I had a 3:7 in my truck stock and it's the perfect gearing. When I blew that rear end I put in a 3:9 from an automatic truck and it made 1st gear useless, it felt torquier but it felt like it didn't really go anywhere on top end.

[_chiefjt]

Sounds good. I think I'm gonna put some 4-1 headers with a 2 1/2" exhaust. And probably the 4:3 from the 620 or 521.

Gonna check the pic-a-part Sunday and see if I come across anything good. I need a tail gate, don't know where to get one.

My ipod just recently got stolen but I'm gonna try and post some pics. probably do a build thread.

[ggzilla]

do a dyno test before and after the exhaust changed. You'll find you lose a bit of HP, but it will sound rad!

[_chiefjt]

hmm. Why would I lose power?

Oh yeah, I noticed I have a 2 piece drive shaft. I want a single one but don't know if the older 720's with the single one would fit? Could I do that?

[wayno]

You have a napZ engine(Z24), that engine is a torque monster, it was never designed to scream, so the stock exhaust is quite likely sufficient, why spend money for zero gain.

Are you having issues with your driveline?

If you change to a one piece driveline, you will quite likely have to start cutting pieces of your frame off, and that would also basicly trash your e-brake, I don't know about you, but I like my e-brake.

Personally I would get it running good(tune-up, ect.), and enjoy it for what it is, and maybe lower it some, would have to see it though, it might already be lowered. B)

 

BTW, Welcome to Ratsun

[ZackeryNM]

I'm 16 as well! welcome! I have a project 92 VW Corrado and a favorite/daily 1986 720 z24 2wd. My advice is that of wayno's... tune it up and enjoy the ease of a daily driver. I personally wouldn't mess with something as reliable as my truck. Last week I beat a riced-up honda accord at a stop light. I don't know about the z22's but the z24 will do work when you want it to. About how long have you been driving the truck? Not how long have you owned the truck... but how long have you been driving it?

[Dead91silvia]

I know what it's like when your 16 and want to mod everything. I drove my dads (now mine) 1980 720 with an L20 motor. It's slow as hell and sounds like a group gerbils are being mutated when you try and haul ass.. I have 2 1/2 in exhaust on my 400hp 350 in my 67 Chevy, no way does a stock 85 Nissan with a 4 banger need one that big, like was said, it will be a hindrance. Some motors need a little back pressure, also you can end up with popping on deceleration and that sounds like crap in my book.

 

Now as for modding, you do have options. Biggest I would go on the exhaust would be a 2" at max! I had a 2 1/4 on my mild built 83 Celica with a 22re and it sounded like a beast with that and a header. I had a 3" with my Silvia, but it was silent with the SR20DET.

 

Like everyone else has said, make sure she runs tip top first and foremost! Then make it look good, paint, body work, wheels, lowered, custom stuff. Then make the interior clean, maybe a set of Honda seats of Z car seats.

 

You never know, you might happen to find a crazy cheap Nissan Hardbody and get a KA24 motor (almost the same as a 240sx) and trans and those are pretty damn fast! I had a 91 with a 5 speed and almost sold my 94 Toyota truck because it was so fun to drive. So I would wait on the motor stuff and do the cosmetics and reliability to start.

 

Anyway, nice to see another 720 guy around! :thumbup:

[datzenmike]

The stock down pipe on the 720 is, I think, 2" and perfectly matched to keep the exhaust speed up at normal speeds where you drive most. A fast moving exhaust will pull more exhaust out of the cylinder so slowing it down with a larger pipe at lower speeds will reduce efficiency at a small gain at top RPM. Bigger is not always better. If you do not have smog testing, removing the cat and running straight 2" to the muffler will gain you more than replacing it all with 2 1/2" pipe. Get the largest 2" muffler you can find that fits under there and run a tailpipe, call it good.

 

Z22 with automatics had a 4.11 differential. '80 L20B motor 2 and 4wd had 4.375 diffs. These should be cheap (about $50) if you pull them, so try them and pick which one you like. Be sure to remove the tranny speedo cog and keep with the diff you choose (they and actually a matched set) so your speedo will remain accurate. This will give a nice increase in torque at the loss of mileage.

 

The biggest bang for the buck is a Weber carb from Redline. Be sure to get a 'direct replacement' for your year and model. The Z24 has a somewhat undersize carb for it's size and 720 owners rave about the performance increase. You can get them delivered for just under $300. I know it seems a lot but it includes everything in a kit and is properly jetted. This will only work if your truck does not have an O2 sensor and either an electronic feedback carb or throttle body injection... so check.

[_chiefjt]

Thanks for all the good feedback. My knowledge is average with "automotive mechanics" cause my dad's been one for 20+ years. It runs very strong and all original. From bumper to bumper, from hoses to the clamps that hold'em. The interior is all original and in good condition. The exterior and paint is even original but faded because of age. I'll try and post all the pictures in the project datto.

 

Still have same ideas on what I want to do. In no rush to mod everything cause I don't want to ruin the originality of it. But just went to the pic-a-part today and got a roll pan, passenger seat belt, the anti-backfire valve and missing plastic pieces for the chrome trim. Overall pretty good day to begin.

 

Oh yeah, I haven't really been driving it, just up and down the street but i just got the title so it'll be on the road soon.

[_chiefjt]

Got the truck registered now. It is now on the road and runs smooth. I had a hose leaking antifreeze but is now fixed and temp. never reaches half way. :)

 

The BAD:

I HAVE NO PERMIT/LICENSE SO MY PARENTS BRAG ABOUT HOW GOOD IT DRIVES.... -_-

 

Makes me mad a bit.

[SHORTDOG]

You have no permit and no license but you do have a nice running 720 pick up?? Where's the reason to be mad at all? I'd say that you are ahead of the game where you stand. Keep up the good work! :thumbup:

[_chiefjt]

Yeah thats true. Just wish i could drive it more myself than sit in the passenger seat and hear all the good times their having. lol

[ggzilla]

photo?

[_chiefjt]

I don't know how to do it from an iphone. I can hook it up to the computer but don't know how. How do I do it? I have lots of pictures.

[ggzilla]

Get the Snapbucket app for your iphone, that's how.

 

Then in Ratsun, use the IMG button and paste in the Snapbucket "Direct link" for the photo.

[ratsunissan]

if you need parts for the motor let me know ha. i got a complete running motor and tranny (w/ weber carb) that i want to get rid of

[_chiefjt]

Thanks, I'll try that.

 

Also, thanks for the info, I'll remember but right now it's running cherry.

[ZackeryNM]

 

I HAVE NO PERMIT/LICENSE SO MY PARENTS BRAG ABOUT HOW GOOD IT DRIVES.... :sleep:

 

Makes me mad a bit.

I personally bought the vw when I was 14... I hated that.

[bryant2482]

you were talking about changing your 2 piece driveshft to a 1 piece. just letting you know i ended up swapping out my 2 piece for a 1 and it worked out great! no frame cutting or anything like that at all! just remember that if you do that 720's have 2 different transmission lenghts. be sure to do some measuring

[_chiefjt]

Thanks, What was your measurements and what driveshaft did it come out of?

[bryant2482]

well i have the fs5w71b long tail (31") long trans and im not sure of the exact lenght of the shaft but the best thing you can do is measure your 2 piece one and check out the junk yards and find out which single shaft is the same lenght. oh and if you find one make sure its balanced and check your joints for play. if you cant find one check out "Dan's Drive Line." their located up on gowan and rancho

[bryant2482]

sory for the late responce. forgot about this post lol