Newbie needs some pointers on some 720's

BlackCasio
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Newbie needs some pointers on some 720's

#1

Post by BlackCasio » Sun Nov 10, 2013 11:43 am

Since I'm new I'll intro my trucks, then get to the questions.

My first truck is an '81 720 4x4 Longbed with the stock z22, 32/36 Weber, and 131, 000 miles. Since I've had it, it's gotten new gaskets, u joints, tires, a canopy, and a new clutch system.
I stopped driving her because I had a spark plug blow out in the Blue Mountains in Oregon. I topped off the coolant, changed the oil, and a few weeks before it had gotten new plugs, wires, and distributor cap. I'm still trying to figure out what the problem with it is because when the plug blew out the ceramic popped out of the metal bolt in part and neither part had any chips or breaks, but it sounds like there might be something in that cylinder (lots of backfires and sputtering).
Anyway, here it is and any ideas would be much appreciated.
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This is the first day I owned it, the previous owner didn't know or care to replace the clutch master cylinder so he had that bottle of brake fluid riding there at all times.
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I don't know what happened to my plug that blew out, but this is the closest picture I could find. Not broken at all, just separated.
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My second truck is an '82 720 diesel with the stock sd22. It just rolled over 265, 000 the other day! Since I've had it, It's gotten a new front fender, new clutch system, door handles, door hinges, and Wayno helped me with my parking brake, some wiring issues I had with tail lights, and showed me how to shut my truck off if my injection pump stops working (unplug and plug back in and she works), I just need to find a new one.
This truck hasn't had any mechanical issues since I've owned it, but just the other day it developed a tick. I thought it was my valves, but I adjusted them to the height suggested in Chilton's and its still ticking away. I have no loss in power, no electrical things have stopped working, at idle it sounds completely normal, and the trans shifts good as it always has. The ticking only happens when driving and is loudest when decelerating in gear (all gears). I am completely stumped on this and would really appreciate any ideas or input on the problem as this one is my daily driver. I'll answer any questions to the best of my knowledge and can provide more pictures or videos as needed.
Here she is:

Had a canopy when I got it, but took it off as I thought it looked bad.
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Thanks guys, and I hope you enjoy!

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izzo
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Re: Newbie needs some pointers on some 720's

#2

Post by izzo » Sun Nov 10, 2013 12:08 pm

Get rid of champion plugs. use NGK only on datsun/nissan. They work best.

But, that is quite the shit man. I've seen plugs blow out, but that was due to shitty threads. For what it's worth that is a rusty ass plug. looks like it just gave out. You replaced them and it still runs funny? check your wire, it could be junk, also check under the cap. the rotor, the cap... check all contact points.

check the compression, too. just for shits and giggles. if some of the pieces of that plug got down in your cylinder, it could have bent an exhaust valve when exiting. Ive seen something as soft as panty hose bend a valve.

If that's the case. Fret not. Find a U67 L series head and put it on that motor. Have yourself a little monster power motor...
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Re: Newbie needs some pointers on some 720's

#3

Post by 510freak » Sun Nov 10, 2013 1:26 pm

Welcome to NWD

Wat izzo said, Champion are garbage right out of the box,limited life span.
Go NGK all the way.

if you have an Digital Multi Meter(or a analog Multi meter) check for resistance on the wires(set in ohms on resistor)

Also like izzo said,f you put a U67 on there, you will have a little power house!
Taterhead » Tue Dec 08, 2015 6:35 am wrote:[quote="Taterhead » Mon Dec 07, 2015 2:41 pm


Sorry, I was channeling my inner flatcat.

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Re: Newbie needs some pointers on some 720's

#4

Post by flatcat19 » Sun Nov 10, 2013 2:01 pm

That happened because of crap plug.
NGK. That is an echo you here.

BlackCasio
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Re: Newbie needs some pointers on some 720's

#5

Post by BlackCasio » Sun Nov 10, 2013 2:52 pm

Sorry I didn't make it very clear. That picture of the spark plug isn't the plug that blew out of my truck, its just the closest picture of what mine did. I had all NGK plugs in it that were new 2 weeks before starting my trip through the Blue Mountains. A new head is what I was thinking but wasn't sure what would work. Does the U67 bolt right on? And I've started searching for one of these, are there any credible places that rebuild them or am I stuck to searching eBay and craigslist?

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Re: Newbie needs some pointers on some 720's

#6

Post by flatcat19 » Sun Nov 10, 2013 4:11 pm

Where are you located? That will determine how easy to find the needed parts for put an U67 on.

Will a U67 fit? Yes. BUT...you have more work to do.
You will need the whole front of an L20B motor to make it work.
That is the basis on an LZ22 motor. And they are rad!

Front cover. Head. Valve cover. Gears. Spindle. Dizzy/pedastal. Thermostat/water outlet housings.

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flatcat19
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Re: Newbie needs some pointers on some 720's

#7

Post by flatcat19 » Sun Nov 10, 2013 4:12 pm

The plug that did blow out of your head---
Did it pull the threads out? What did the electrode look like?
Were they even the correct plugs for that motor?

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Re: Newbie needs some pointers on some 720's

#8

Post by wayno » Sun Nov 10, 2013 4:22 pm

Does it make the ticking sound when in neutral with the clutch pedal not pushed in?
Does it stop making the sound when you push the clutch in and put it in gear?
Does the ticking sound different in 4th?
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Re: Newbie needs some pointers on some 720's

#9

Post by datsunmike » Sun Nov 10, 2013 4:32 pm

Way easier to find another Z20 or Z22 head than converting to an L head. You will need L series timing cover /carb/manifolds and the intake will be tilted about 20 degrees to the left and I doubt will clear the brake master cylinder. That's even if it needs one. To rule that out ...

Don't assume... check that the plug wires go to the right plugs. And make sure the the intake and the exhaust sides are firing. Inspect the wires themselves, the rotor and the cap. There are 8 plug wires and not much space between them on the Z series dizzy cap, so they have to be in good shape.
Check your valve lash, should be 0.013" on all of them. A tight valve will cause misfire.
Do a compression check on all cylinders. One low or two adjacent low compressions may just be a blown head gasket.
My Datsuns, like good friends, have never let me down. At least in any way that was not understandable and thus fixable.

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Re: Newbie needs some pointers on some 720's

#10

Post by flatcat19 » Sun Nov 10, 2013 5:21 pm

Depending on location...
I have a 4 plug Z head and 4 plug dizzy on the block.

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Re: Newbie needs some pointers on some 720's

#11

Post by wayno » Sun Nov 10, 2013 5:26 pm

He is in the Portland area.
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Re: Newbie needs some pointers on some 720's

#12

Post by flatcat19 » Sun Nov 10, 2013 5:48 pm

Perfect. I'll be there soon.
I haz if you want.

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Re: Newbie needs some pointers on some 720's

#13

Post by BlackCasio » Mon Nov 11, 2013 7:33 am

Flatcat19, the threads did not pull out, just the core of the plug blew out. The electrode was fine and from what I could tell there were no chipped or missing pieces. I am positive they were/are the right plugs. Also, I've gotta get the diesel in better shape before I start compiling for the gas truck. I will be in contact and send you a pm (hopefully soon) when I'm interested in doing more.

Wayno, thanks for getting back to the diesel problem. There is a different sound when you let the clutch out in neutral but it hasn't gotten any louder since you told me it wasn't bad. It's the same loudness in all gears, but no performance loss whatsoever.

Thanks for that bit of info datsunmike, I adjusted them all to 0.012. I'm new to valve adjustment, would that 0.001 make a difference? And now that I think about it, I was teaching a to change distributor cap, wires, and plugs and I walked away at the end.... may have just found the problem.

I'll post an update after I do a one over on the spark system.
Thanks guys

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Re: Newbie needs some pointers on some 720's

#14

Post by BlackCasio » Mon Nov 11, 2013 7:34 am

*I was teaching a friend to change the distributor....

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Re: Newbie needs some pointers on some 720's

#15

Post by wayno » Mon Nov 11, 2013 8:49 am

You have to decide if it is the front lower cluster gear bearing that is making the noise, as you don't want it to self destruct, it will make noise when the input shaft of the transmission is turning, and the noise will stop when it is not turning,
In neutral with the clutch pedal not pushed in does it make noise?
When you push the clutch in and put it in first, does the noise stop?
Remove the fill plug in your transmission, put your finger in the hole and reach down as far as possible, when you pull it out, what color is the gear oil, silver, black, brown, or sort of a clear honey color?
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Re: Newbie needs some pointers on some 720's

#16

Post by izzo » Mon Nov 11, 2013 10:01 am

BlackCasio wrote:Flatcat19, the threads did not pull out, just the core of the plug blew out. The electrode was fine and from what I could tell there were no chipped or missing pieces. I am positive they were/are the right plugs. Also, I've gotta get the diesel in better shape before I start compiling for the gas truck. I will be in contact and send you a pm (hopefully soon) when I'm interested in doing more.

Wayno, thanks for getting back to the diesel problem. There is a different sound when you let the clutch out in neutral but it hasn't gotten any louder since you told me it wasn't bad. It's the same loudness in all gears, but no performance loss whatsoever.

Thanks for that bit of info datsunmike, I adjusted them all to 0.012. I'm new to valve adjustment, would that 0.001 make a difference? And now that I think about it, I was teaching a to change distributor cap, wires, and plugs and I walked away at the end.... may have just found the problem.

I'll post an update after I do a one over on the spark system.
Thanks guys

I am pretty sure they are supposed to be at 12, that's what the book said. make sure you do this when the engine is at normal running tempature.

PS, most dizzy caps will say where the plug goes to man. If you look at the front of the motor to the back. The cylinders 1 2 3 4. Look on the cap, it will say E1, I2 etc. Well just read it... E1 is exhaust one I2 is intake cylinder 2, E4 is exhaust cylinder four.....

but for shiggity reasons.

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Re: Newbie needs some pointers on some 720's

#17

Post by BlackCasio » Mon Nov 11, 2013 11:27 am

I don't have time to go look at the spark system until later.

Wayno, if the clutch is not pushed in while in neutral it makes a quiet noise, but not the ticking I hear while driving. There is no change in sound for any gear you put it in if the clutch is pushed in. It's hard to distinguish where the sound is coming from as it is only heard while driving and is loudest on deceleration.

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Re: Newbie needs some pointers on some 720's

#18

Post by wayno » Mon Nov 11, 2013 3:34 pm

You need to figure out if it's the front bearing in the transmission, if it is, you need to quit driving it before it self destructs, diesel cases are very hard to find, and steel front bearing covers are even harder to find.
Check the color of your transmission gear lube/oil.
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Re: Newbie needs some pointers on some 720's

#19

Post by BlackCasio » Mon Nov 11, 2013 5:13 pm

Wayno, I checked the fluid and it is a clear honey color. Whats the verdict for that?
I also noticed quite a bit of oil or tranny fluid (not sure which) on the undercarriage that wasn't there last time I checked something under the truck.
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Re: Newbie needs some pointers on some 720's

#20

Post by wayno » Mon Nov 11, 2013 7:30 pm

That could be blow by from the block vent, or it could be that the front bearing cover has already been destroyed, lets just say it's blow-by as that is the vent tube exit that is blue.
I actually would have to see the truck in person to determine if it was the transmission, or something else, check your exhaust bolts to the head and the down pipe connection from the manifold itself, figure out everything it is not.
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