84 720 kc project

[mattmctree@gmail.com]

hi all im new here,

 

ive got an 84 720 4x4 and am starting a project on it. im gonna try and keep the z24 thats in it but have heard about the cracked block issues. i like the idea of making it simple so i thouhgt of putting a l20 with mech fuel pump and points and condenser carb. i was told it might be tricky to fit an l20 to a z24 tranny. any ideas?

 

id love to work on my truck more but considering its at a friends farm field its kinda tough

 

 

[bilzbobaggins]

Welcome!!!

Why loose the displacemnt? And step backwards with points? You could fit the l20b to the z24 trans, but it would have the wrong tilt. There is a difference in bellhousings. You could swap them. Do you have a L20b setting around? Whats wrong with the motor now?  Blown headgasket?

My favorite link. When I get an idea, I go here and use this to search. Another member made the link.
 

http://www.google.com/search?hl=en&q=site%3Acommunity.ratsun.net     Do lots of searching.  All kinds of good stuff.

 

Good Luck.

 

Wheres the pics?

 

Jeff

[Jayden71]

You're gonna lose lots of torque going from z24 to L20b. Why points?? Only guys that are afraid of zombies run points.

[datzenmike]

See if this helps.... the L20B has a maximum of around 108 foot pounds of torque at 3,200 RPMs (and 65hp) Torque is what pulls a vehicle around. The Z24 makes 134 foot pounds torque and 70 hp at a lower 2,800 RPMs or about 1/3 more torque and closer to idle where you really feel it accelerating from a stop.

 

The L20B makes about 95HP at 5,800 RPMs and this works out to 85 foot pounds torque.

The Z24 makes about 103HP at 4,800RPM and this works out to 112 foot pounds torque. More power and torque at lower speeds is good for hauling a heavy 720 around cracks or no cracks.

[bonvo]

or if your dead set on swapping why not go ka? the single cam bolts to your trans if i remember right and is an all around better engine

[Kingman]

Put SUs on an L20B and you'll have shitloads of idle-up torque.

[datzenmike]

But it won't equal a 2.4

[ssnapz]

never go down on displacement. if you dont overheat your motor it wont crack and any motor you overheat will crack or blow a gasket. i love my naps24.

[mattmctree@gmail.com]

ive got a free l20b from a farmer down the road.

what its meant by su's, sorry om pretty new to all this.

haha i just like old school simple stuff so the whole zombie thing isnt the reason

im in ontario near toronto and finding parts for these trucks are like hens teeth!

so if i got a bell housing from the l20 tranny i could put it in correct? would a z22 bolt up to a z24 tranny without mods?

thanks for all the tips.

[ssnapz]

keep the l20 but run the z24 if it runs. carbs are simple if you give them fuel and can bolt them up they work, too big or too small still work. i run a holley on mine and runs great. not as cool as su's but probably runs better and definitely more reliable. i would never change motors cause the block might crack. if its blown and you have a l20 and bell housing, why not. 

[mattmctree@gmail.com]

Ive got a 84 4x4 nissan 720. im always looking for parts for it. extra fuel pumps, starters, windows etc. If im in a junkyard and i find datsuns or nissans what years can i scavenge parts from? can i take any from 70"s era or even hardbodies? what about nissan datsun cars? any tips would be great! thanks. also what is a fair price for a wrecker to ask for parts for the motor , windshields etc?

 

thanks

 

[bonvo]

any 720 for body and interior stuff (minor differences between years but should bolt up 

 

for engine stuff anything with a z series engine in it but i think that only the trucks came with carbs on them 

[HRH]

First of all, you have.  Not I've got.  I have got is present/past tense.  Mixing of the tenses.  You either have something, or you got something.  You can't have both.

 

Second, 83-86 4wd systems are basically the same.  80-81-82 there are some differences being it was basically a 2wd setup that they modified to accept 4wd.  They didn't get into more refined versions until 83.  After 86 systems of D21 vintage are more desirable because of equal length shafts in the front end vs a long and short cv axle on the earlier models.  The D21 also got the married transfer case, which the 720s didn't get.  Good for strength, also more annoying to yank the transmission/transfer case assembly.  The 720 is nice for having an easily removable and robust transfer case and unfortunately a fairly weak tranny.  But with the power the Z24 made, not a big deal.  More u joints to replace on a 720 definitely with the case being separate.

 

Interior trim bits will mostly fit between just about all 720s except for some early grills and stuff.  I think the core support may be different on '80 model 720s.

 

Lastly, don't hoard shit.  Literally.  If it's in the wrecking yard, it's there for a reason.  A lot of it will be shit.  Stuff that can't be replaced, yes.  Starters?  No.  No one cares if the starter is new or old, or the vintage.  It just needs to work.  Save one for a core in case you build a different motor and you need a core for the new remanufactured one you buy.  

[mattmctree@gmail.com]

i dont have a camera so this might be a pain to describe. but here it goes. i wanted to get a fuel pump relay from a 81 720 for my 84. i went to a junk yard an pulled a small black cube with 6 spades on the end from the glove box area. upon looking at my fsm it looks like i grabbed the inhibitor relay? can someone pos pics of what i should have grabbed?

also.

any i dea what i should offer the wreckers for a z22s block? i have no idea how the engine is but the rest of the truck is rotting and just sitting in the dirt

 

[ggzilla]

Fuel relay looks like this:

 

 

 

25230-81W00 is the 6-pin relay and is for CAL models (look on the underhood sticker or door jamb sticker to see if yours is a CAL model)

 

AT Inhibitor relay is C9920/C9925 and is on the drivers side.

[datzenmike]

Actually it looks like this

 

 

It's somewhat like the interior lamp timer. I think there is a timer set when cranking. Maybe 10-20 seconds of fuel pump to get the motor started then, if there is no oil pressure or no alternator charge, the pump cuts out.

 

 

 

The fuel pump relay was used from Oct '82 and on all 720s with the Z20 and Z24 motor and is part # 28545-89900. Prior to this the fuel pump was on when the ignition was on.

 

 

25230-81W00 is the 6-pin relay and is for CAL models (look on the underhood sticker or door jamb sticker to see if yours is a CAL model)

It's not clear to me what this relay does but wasn't use before Jan '85 on all California Z24 powered trucks. Probably for the high pressure fuel pump for the throttle body injection on the Z24i motors.

[DISLEXICDIME]

i soldered my old relay back together the soldered joints crack and come apart

[ggzilla]

Ah i see you are correct. The one I listed is used for something else on the 720 (and for fuel pump relay on other Datsuns).

 

28545-89000 In-tank Pump Control Unit

 

For sale on Ratsun - $10

[mattmctree@gmail.com]

cool thanks for the tip. english never was my best subject

[datzenmike]

It would be far easier for you to ask about parts that you want rather than us naming every 720 part that might or might not swap.

 

 

 

 im always looking for parts for it. extra fuel pumps, starters, windows etc.....  also what is a fair price for a wrecker to ask for parts for the motor , windshields etc?

 

thanks

 

All year 720 electric fuel pumps (for gas motors) are pretty much the same. Except the '80 which was mechanical and unique to that year. From Jan '85 on, a high pressure electric pump was used for fuel injection.

 

The '80 starter is unique to that year. It is for the smallest motor used on the 720 but will fit and work on all later larger gas motors.

 

All year windshields should fit but there were 4-5 kinds, clear, tint, made in USA and some '85s had an antenna embedded in them.

 

I would say that if there are lots of 720s near you, and even if not, grab anything you think you need. Because one day you'll go back for something and the guy will say... " Those Neesans? They all went in the crusher two months ago. Coulda kept one out if you'da  toll me" Now NO-ONE has them. Once gone they are gone forever.

[mattmctree@gmail.com]

aweomse thanks.

[mattmctree@gmail.com]

so after a year and a half i finally got my truck in a garage. im going to get it running and want to start fixing it up. the body is a bit rusty but im not to concermed. im going to put it on stands and start to look for frame rot? im a newbie here so other than looking for cracks or gaping holes im not to sure what to look for? are there any prone areas i should be looking at? whats the best way to look for it?

 

thanks

 

[datzenmike]

It's a box frame meaning that it's a square or rectangular cross section. I don't know if they are the same as my old 620 but it was formed with a welded seal about half way from top to bottom along the length and facing the inside where you wouldn't see it. Mine rotted completely away leaving only the outside face in some spots. 

 

XXX

X  X

X  X <WELDED SEAM HERE

X  X

XXX

[mattmctree@gmail.com]

so i was looking at my frame the other day on an 84 720 , on the frame there are some holes ( factory) and i was suprised at how thin it looked? how thick are the frame rails supposed to be? i didnt have a tape measure, but it looked to be less than a quarter inch?

 

 

[datzenmike]

I would say close to 1/8" but not above that I think. What gives  the frame it's incredible stiffness is the box cross section.

 

I have an '82 frame and just measured it. With paint and some slight rust crust it was 0.135"  That's 10 thou above 1/8" which is 0.125"