Vacuum line delete on 720

[builte]

I have a 1986 Nissan 720 kingcab 2wd automatic transmission do I need to swap in my factory carb for a weber to do a vacuum line delete? I would like to keep the original carb as it works perfectly for me and the Weber is a bit pricey.

[builte]

As far as I can tell I only need one line but not very many of the videos even come close to showing exact which one it needs and what I can get rid of

[datzenmike]

The first emissions devices simply tried to correct emissions that were already present in the exhaust.

The next generation of emission devices altered the engine running on start up and part throttle to reduce emissions. The 720 is in this category.

The latest emissions devices completely control the engine and transmission and won't allow the engine to run in conditions where it pollutes.

 

 

All the vacuum lines can be kept as they all have a function. None of the 'emissions crap' affects performance only part throttle, however if the hoses are allowed to deteriorate they could leak and that would affect idling. If not careful, deleting them can actually cause problems. The fuel cut system actually saves gas. The EGR is defeated at full throttle so has no effect on performance. The AIS (air injection system) has zero effect on running and helps the catalytic converter clean the exhaust emissions. The charcoal canister simply stores gas fumes and is benign in operation. The ATC (automatic temperature control) adjusts the intake air temperature to a constant 90F so the engine operates consistently over a wider range of outside temperatures. A Z24 with everything removed will not run any better than one that's been properly maintained with everything kept.

 

Often they are simply removed for no good reason. Almost no one understands what all the emissions devices do...

 

 

 

The only vacuum lines strictly necessary for running are the one to the brake booster, the small one to the automatic transmission and the vacuum advance to the distributor. 

[builte]

Thank you Mike your a real hero it probably kills you to know I'm taking them off honestly just do not like the way the look

[datzenmike]

lol Do as you like. I don't mind. Esthetics are as good a reason as any.

[NC85ST]

Don’t fix what ain’t broken. If it runs good, leave it alone. You said it’s an ‘86, that’s a little more complicated. Strictly speaking, that’s not a carburetor, it’s half way between a carburetor and fuel injection, if I’m not mistaken. Does it have two wing nuts holding the air cleaner lid?

[Stoffregen Motorsports]

Swap to a DGV or DGAS to help simplify things.

[builte]

1 hour ago, NC85ST said:

Don’t fix what ain’t broken. If it runs good, leave it alone. You said it’s an ‘86, that’s a little more complicated. Strictly speaking, that’s not a carburetor, it’s half way between a carburetor and fuel injection, if I’m not mistaken. Does it have two wing nuts holding the air cleaner lid?

 

It does not have two wingnuts

[builte]

1 hour ago, Stoffregen Motorsports said:

Swap to a DGV or DGAS to help simplify things.

 

Can you elaborate on simplify I've seen on other 720 posts were they made the swap but do I really need to swap to delete egr?

[datzenmike]

To deactivate the EGR just pull the vacuum line off. Removal involves removing the exhaust pipe to the exhaust manifold and removal of the EGR valve and making a block off plate. Both risk snapping rusty studs or worse a vacuum leak. We had a guy years ago tore all his wiring out of his truck in the first few months. For the next year he was constantly asking where wires went and what they did, or 'why are my signals not working?'

[Thomas Perkins]

Keep them all.I do and it runs perfect.

[DwayneOxford]

3 hours ago, datzenmike said:

To deactivate the EGR just pull the vacuum line off. Removal involves removing the exhaust pipe to the exhaust manifold and removal of the EGR valve and making a block off plate. Both risk snapping rusty studs or worse a vacuum leak. We had a guy years ago tore all his wiring out of his truck in the first few months. For the next year he was constantly asking where wires went and what they did, or 'why are my signals not working?'

My maternal grandpa was an ace mechanic in his day. In WW2 gas and tires were rationed. Added a head gasket and small gas tank on Model A. Crank and warm on gas, had line from big tank wrapped around exhaust manifold couple turns, turn on the kerosene when warm. Went back to gas before shut off. Traded his gas coupons for tires. That said, he had a customer who'd bring his car pretty often. Pa'd retune it and charge him. Fellow asked what was wrong with it, Pa said, "Your head under the hood". Moral, If it ain't broke, leave it be.

[builte]

20 hours ago, datzenmike said:

To deactivate the EGR just pull the vacuum line off. Removal involves removing the exhaust pipe to the exhaust manifold and removal of the EGR valve and making a block off plate. Both risk snapping rusty studs or worse a vacuum leak. We had a guy years ago tore all his wiring out of his truck in the first few months. For the next year he was constantly asking where wires went and what they did, or 'why are my signals not working?'

I didn't remove any wires from the truck just the positive and negative terminals a few different ground and plugs but I took a few pictures just in case I got the transmission disconnected ok and I'm waiting on my dad to help me pull it out of there right now 

[Stoffregen Motorsports]

23 minutes ago, builte said:

I didn't remove any wires from the truck just the positive and negative terminals a few different ground and plugs but I took a few pictures just in case I got the transmission disconnected ok and I'm waiting on my dad to help me pull it out of there right now 

I think Mike was trying to illustrate that by understanding what and how each and every device functions, you'll be able to fix or modify anything under the hood. Understanding how and why the vacuum lines are connected can help you build your own road map for deleting items.

 

Conversely, tearing into it and deleting things because they look nasty can lead to many hours of head scratching.

 

I find that taking time to clean the engine and all the under hood parts gives you a better appreciation for all the doo-hickeys. Take some time to replace all the hoses and route them in a way that makes sense, visually and mechanically, and you might change your mind and decide to leave all those pieces. Thomas' engine bay is a good example of that. It's almost totally stock, but he's spent tons of time detailing everything and it shows. The devil really is in the details.

[builte]

I'll have to check that out I already got most of it removed so I can take the engine out without breaking everything but if I can find some better look lines and reroute them to make maintenance easier I will keep them how they should be I'll have to learn what all of it does. Thank you all

10 hours ago, Stoffregen Motorsports said:

I think Mike was trying to illustrate that by understanding what and how each and every device functions, you'll be able to fix or modify anything under the hood. Understanding how and why the vacuum lines are connected can help you build your own road map for deleting items.

 

Conversely, tearing into it and deleting things because they look nasty can lead to many hours of head scratching.

 

I find that taking time to clean the engine and all the under hood parts gives you a better appreciation for all the doo-hickeys. Take some time to replace all the hoses and route them in a way that makes sense, visually and mechanically, and you might change your mind and decide to leave all those pieces. Thomas' engine bay is a good example of that. It's almost totally stock, but he's spent tons of time detailing everything and it shows. The devil really is in the details.

 

[Thomas Perkins]

10 hours ago, builte said:

I'll have to check that out I already got most of it removed so I can take the engine out without breaking everything but if I can find some better look lines and reroute them to make maintenance easier I will keep them how they should be I'll have to learn what all of it does. Thank you all

 

 

[Thomas Perkins]

Go to my you tube page.Tommy Perkins.I have 2 showing my Weber and vacuum.lines.They are 85 Nissan 720 4x4 walk around,that is my newest and 1985 Nissan 720 4x4 Weber conversion

 

[builte]

Doing that now 

[Thomas Perkins]

They should be the same.People eliminate there vacuum lines,then have problems and wonder why there 720 is not running good.I've had my 720 for 29 years,go to my Ratsun page and check it out.I do have a FSM Manual.You know in 86.5 they changed the 720,carb was replaced.When you get parts,use the 85 year.

[Thomas Perkins]

The automatic does not have a AB valve.I don't use it with Weber.

[builte]

2 hours ago, Thomas Perkins said:

They should be the same.People eliminate there vacuum lines,then have problems and wonder why there 720 is not running good.I've had my 720 for 29 years,go to my Ratsun page and check it out.I do have a FSM Manual.You know in 86.5 they changed the 720,carb was replaced.When you get parts,use the 85 year.

What carb should I get for mine like what would be compatible 

[Stoffregen Motorsports]

I think it's time for you to start a build thread. You've got the same content in so many different pages now, it's hard to keep up.

[powderfinger]

On 8/27/2023 at 10:46 AM, NC85ST said:

You said it’s an ‘86, that’s a little more complicated. Strictly speaking, that’s not a carburetor, it’s half way between a carburetor and fuel injection, if I’m not mistaken.

Pretty sure the z24i engine was only on the ST in the later 86 models. Not 100% sure on that though. My 4x4 was a z24i engine before I converted it to a weber, it's an 86 ST. I think it was a mid-year change on the ST models, at least that's what I recall my FSM z24i service manual add on saying.

Edited August 30, 2023 by powderfinger

[builte]

2 hours ago, Stoffregen Motorsports said:

I think it's time for you to start a build thread. You've got the same content in so many different pages now, it's hard to keep up.

How do I start a build thread lol I get lost on this site 

[datzenmike]

2 hours ago, powderfinger said:

Pretty sure the z24i engine was only on the ST in the later 86 models. Not 100% sure on that though. My 4x4 was a z24i engine before I converted it to a weber, it's an 86 ST. I think it was a mid-year change on the ST models, at least that's what I recall my FSM z24i service manual add on saying.

   

It was on all California emission trucks from '83.

 

 

22 minutes ago, builte said:

How do I start a build thread lol I get lost on this site 

 

Look just below the 'Rats 'n Wrenches' logo top left for BROWSE. Drop down through GENERAL to Project Datto. Over on the far right is a blue rectangle with Start New Topic..... go to town. Pictures are important.