Lots of work to do on the 720.

[datzenmike]

57 minutes ago, None_zero said:

Who am I kidding I have a billion questions still, chief among them are these 

Does anyone sell replacement overflow tanks for the rad mine has a giant hole eaten out of it? 

Holes in the cat below exhaust manifold signals time to replace ?

 

Any obvious reason why my exhaust coil cable would keep burning up and melting the contact at the coil?

 

That's the coolant recovery tank. It collects expelled coolant usually from heat soak after shutdown and when the rad cools it will siphon back into the rad keeping it always topped up.

 

Do you mean the high voltage cable to the distributor? or the electrical wiring?

 

 

Plug this back in. You don't have the wiring for it sop just leave it.

 

 

The only source for oil is

The valve cover gasket... make sure tightened down.

The dip stick is below this.

The block vent tube is in the bottom left of the picture. Make sure it is snugly pressed into the block.

 

You're going to have to spray clean with carburetor cleaner and let dry, then check more often to see whee the oil show up first.

 

[jagman]

About the overflow tank,  I took the better one off my junker but was putting washer fluid in my wife's 2013 toyota and noticed how nice the radiator tank was in her car.  She realized that I was looking very closely and said that if I had designs on removing parts from her car I would need a step stool to pee. But I think that a toyota overflow tank would work. 

[datzenmike]

You need the special rad cap for the recovery to siphon properly but any container even a pop bottle would work but something that seals is better and the over flow hose must reach to the bottom of any container. I used to top up every week in the summer. With a coolant recovery system maybe a cup a year now.

[EDM620]

On 10/4/2020 at 2:54 AM, Draker said:

cut out the bad metal, weld in new.

Wish my floor was as "solid" as yours was, had to cut out a large chunk of my floor

But like Draker said, cut out the bad metal and weld in some new metal, or you'll end up with a Flintstone mobile...

[EDM620]

On 10/5/2020 at 5:57 PM, Lockleaf said:

https://www.youtube.com/watch?v=_u31t13QO6A

Yeah Fitzee has become a must-watch for me too.

[None_zero]

@datzenmike yes the high voltage cable from dizzy to exhaust side coil I replaced the coil maybe 2-3 months ago so its brand new and it burned out the connecting wire so bad it melted the end of the contact off. ... for the second time now 

[None_zero]

She's back together under to hood currently and running well though I definitely have to get the air fuel mix and idle speed sorted out. Probably wouldn't kill it to hit it with a timing light just to check but I dont have one... now I'm on to finishing the interior of the cab and then fix and remount the bed.  It's coming along nicely 

[datzenmike]

1 hour ago, None_zero said:

@datzenmike yes the high voltage cable from dizzy to exhaust side coil I replaced the coil maybe 2-3 months ago so its brand new and it burned out the connecting wire so bad it melted the end of the contact off. ... for the second time now 

 

Coil should be a Nissan stock coil. With a primary resistance of between 0.75 and 1.0 ohms. If you have some after market coil get rid of it. It's not normal for this to happen. You sure it's the exhaust coil? Pull the first fuse (10amp) on the left side of the box. This powers the exhaust side and should blow before melting wires. 

 

Set valve lash to 0.012" on all.

 

Set timing to 5⁰  with both coils firing. Idle speed at about 800

 

Best to set idle mix with the lash and timing set first but you may need to set the idle just to set the timing. After timing is set check the idle mix for the last time. To set idle mix, turn idle down to as low as you can on a hot engine, at least below 800. Use the idle speed screw. The idle mix screw is under an aluminum plug and set by the factory so you can't mess with it.

 

 

With lowered idle, so it's easier to detect any changes, turn the idle mix in or out looking for the position where it idles faster and stronger. Turn 1/4 turns with several seconds wait between for the engine to adjust. You'll find there is about one full turn where it idles best and falls off on either side. Set roughly in the middle. Presumably the idle has increased so turn down as low as you can and repeat the adjustment. Expect to do this at least a half dozen times. Keep going till you can't improve the idle quality and the idle is at 700-800 rpms. Done.

[Lockleaf]

Recovery tanks can be made from anything that can take the heat.  Liqour bottles are quite popular, large beer/soda cans, etc.  You can buy universal ones in cheap plastic at oreilly or spend huge sums on sweet machined units for some bling.  Junkyard retrofits are another option.

 

240sx aluminum tanks are cheap and might be similar enough in shape to be great.  No promises though...

[None_zero]

20 hours ago, datzenmike said:

You need the special rad cap for the recovery to siphon properly but any container even a pop bottle would work but something that seals is better and the over flow hose must reach to the bottom of any container. I used to top up every week in the summer. With a coolant recovery system maybe a cup a year now.

Yeah mine works but damn its ugly... 

[None_zero]

2 hours ago, Lockleaf said:

Recovery tanks can be made from anything that can take the heat.  Liqour bottles are quite popular, large beer/soda cans, etc.  You can buy universal ones in cheap plastic at oreilly or spend huge sums on sweet machined units for some bling.  Junkyard retrofits are another option.

 

240sx aluminum tanks are cheap and might be similar enough in shape to be great.  No promises though...

I got a chap universal from advanced  I think but it didn't fit in the space. At the time it didnt occur to me to just move it .

[None_zero]

Ok regression is a thing I put everything in the engine bay back together last night and started the  truck. Was running fine though obviously needed adjustment. I started it today same thing running fine but needed to be dialed in I let it run for a  while maybe 10 mins tops while I went to grab the instrument cluster so I'd know when I'd reached operating temp (admittedly I jacked around with the air fuel and idle speed before I was at temp) anyway as soon as i plugged the gauge cluster in one thing at a time starting with speedometer and ending with temp gauge the truck had a couple little backfires bogged  down and died. I disconnect gauges again to see if that's the problem and same thing bogg down dead what happened?

[None_zero]

8 hours ago, datzenmike said:

 

Coil should be a Nissan stock coil. With a primary resistance of between 0.75 and 1.0 ohms. If you have some after market coil get rid of it. It's not normal for this to happen. You sure it's the exhaust coil? Pull the first fuse (10amp) on the left side of the box. This powers the exhaust side and should blow before melting wires. 

 

Set valve lash to 0.012" on all.

 

Set timing to 5⁰  with both coils firing. Idle speed at about 800

 

Best to set idle mix with the lash and timing set first but you may need to set the idle just to set the timing. After timing is set check the idle mix for the last time. To set idle mix, turn idle down to as low as you can on a hot engine, at least below 800. Use the idle speed screw. The idle mix screw is under an aluminum plug and set by the factory so you can't mess with it.

 

 

With lowered idle, so it's easier to detect any changes, turn the idle mix in or out looking for the position where it idles faster and stronger. Turn 1/4 turns with several seconds wait between for the engine to adjust. You'll find there is about one full turn where it idles best and falls off on either side. Set roughly in the middle. Presumably the idle has increased so turn down as low as you can and repeat the adjustment. Expect to do this at least a half dozen times. Keep going till you can't improve the idle quality and the idle is at 700-800 rpms. Done.

Awesome thanks one problem I dont have a timing light. I do however have a strobe light anyway i can engineer a substitute? Also coil was purchased from advanced auto as their recommended replacement so should be legit. It worked after I replaced it for 2-3- months and then one day the wire was melted. It's entirely possible that I did that jacking around in the electrical system though it seems ok now with a new wire on it 

Edited October 9, 2020 by None_zero

[None_zero]

@datzenmike first fuse is 10a I checked it for continuity with my ohm reader and got solid tone. I am saying its the exhaust coil because that's what it says on the dizzy cap where the wire mounts for it. It runs to the coil that is further toward the cab of the truck.  Its mounted behind the purge tank as you stand in front of the truck looking into the engine bay

You can see it there it's the one with the wrong color sparkplug wire I bought a universal kit for making cable because they wouldn't sell me one wire they wanted to sell me the whole set .

[None_zero]

@datzenmike could this be the cause of my coil burning up its wire?

Meaning the rusted contact and corrosion, not that its disconnected I did that to test the voltage and if I'm doing it right I'm reading about 4 volts 

[datzenmike]

wires are easily switched on the cap. It has no effect on running as both fire at the same time but the intake coil would now be firing the exhaust side. The exhaust coil is powered through a fuse but the intake comes directly from the battery, through a fusible link and then the ignition switch.

 

If you pull the fuse from the far left hand side then check for power on the + sides of both coils with the ignition on, the one that doesn't have power is the exhaust side coil. You could then re-arrange the  two wires on the cap. 

 

Definitely a bad connection can cause resistance that will heat up.

 

 

 

[None_zero]

6 hours ago, datzenmike said:

wires are easily switched on the cap. It has no effect on running as both fire at the same time but the intake coil would now be firing the exhaust side. The exhaust coil is powered through a fuse but the intake comes directly from the battery, through a fusible link and then the ignition switch.

 

If you pull the fuse from the far left hand side then check for power on the + sides of both coils with the ignition on, the one that doesn't have power is the exhaust side coil. You could then re-arrange the  two wires on the cap. 

 

Definitely a bad connection can cause resistance that will heat up.

 

 

 

Ok I can do that. Currently I'm a little stumped over what is sure to be some simple shit. I'm trying to set the valve lash and I cant seem to find the part of the rotation where the #1 intake is pushing... to indicate I'm at tdc also I tried to hook up my new timing light as per the instructions just to see if I was firing on all cylinders and couldn't get it to flash on any of them bad light maybe? Operator error likely.... update: ok I believe I'm at top dead center with one plug out should I be hearing a gurgle/sputter hissing sound as I rotate the crank?

Edited October 12, 2020 by None_zero

[None_zero]

Ok so can someone confirm this for me I've never done this before and I'd hate to screw it up. Setting valve lash on z20s I put number 1 to tdc checking that both intake and exhaust valves are closed. Then I set them by firing order to .012. Which is 1-2-4-6 then set the 4th cylinder to tdc and set 3-5-7-8 then close it up and wait for my brass nuts and bolts trophy to arrive via post??

[None_zero]

Also can clean this?

And should I clean these probably?

And what should I use to clean them if I should clean them 

[john510]

Don't clean spark plugs,replace them.

[bottomwatcher]

Spark likes sharp edges if the plug looks rounded or eroded replace. Check your gaps before installing and buy your plugs from a reputable source. Ebay is flooded with knock off plugs. Seems strange that counterfeit plugs would be in issue but everything gets counterfeited these days.

[datzenmike]

For setting the valve lash it only has to be close to TDC. You can do this by eye. Both #1 cylinder valve lobes must be pointing downward and the valves fully closed. As viewed from the front the first lobe will be at about 4 o'clock and the other, the intake valve, at 8 o'clock.

 

 

Warm the engine thoroughly till it is 'hot', set to TDC on the #1 cylinder as per above. Set both intake and exhaust on #1, set the intake valve on the #2 cylinder and the exhaust valve on the #3 cylinder. Now turn the engine exactly ONE turn. This will move the two front valve lobes to about 10 and 2 o'clock. Now set the exhaust on the #2 cylinder, the intake on the #3 cylinder and both valves on the #4 cylinder.... done this way there is no repeated 'bumping over' of the engine and it's quick enough to finish before the engine cools.

 

23 minutes ago, john510 said:

Don't clean spark plugs,replace them.

 

This works also but check the gaps.

[Charlie69]

9 hours ago, bottomwatcher said:

Spark likes sharp edges

Lightning got me and I do not have any sharp edges!  LOL

[None_zero]

@jagman you were right that first mixture failed catastrophically before I even got it reinstalled. It was actually the dynaflex that failed however. To be fair my impatience may have been my undoing there. I think it is very likely that I coated it with the dynaflex before the timber mate layer under it was fully cured. The dynaflex is rubbery and couldn't allow the outgasing that was inevitable due to nature and its pesky laws. Anyway I scraped off the dynaflex layer and as everything under that was still pretty well intact I left most of it and went over the top with a product called fast and final. It's for drywall but it doesn't cure as brittle as most spackling does. I chose the fast and final for exactly 3 reasons, #1 I didn't want to spend a lot of time on this #2 I didnt want to do it again.... #3 I had some on hand. I'll let you know how it goes when I get done shaping and painting. So far though it's looking pretty damn good. 

Edited October 14, 2020 by None_zero

[None_zero]

On 10/9/2020 at 5:59 PM, None_zero said:

Awesome thanks one problem I dont have a timing light. I do however have a strobe light anyway i can engineer a substitute? Also coil was purchased from advanced auto as their recommended replacement so should be legit. It worked after I replaced it for 2-3- months and then one day the wire was melted. It's entirely possible that I did that jacking around in the electrical system though it seems ok now with a new wire on it 

Ok getting there slowly so my timing is hitting 0 dead on the money to change... (advance?) It to 5 i loosen the dizzy on its bracket and rotate clockwise? Currently near or at op temp setting at 700 rpms max and she sounds decent.i dont know if I'd call this purring but she's doing the damn thing

Edited October 14, 2020 by None_zero