A little vacuum and smog help (1982 720 Z24).

[720_Daniel]

Hi all, 

 

I'm reinstalling the emissions controls so I can get this truck past smog in CA. I've mad a lot of progress, but have 3 loose ends that I can't figure out. 

1. What hooks onto the big tube on the carb? Carb float valve vent? Anything? The guide I was looking at was from a 1984, and nothing on the vacuum diagram shows anything hooked there. 

2. Brake booster hose has a capped vacuum line. Should I concern myself with that? It isn't on the diagram either. 

3. The dumbest question: Where the hell does the pre-heater hose go on the exhaust manifold? I can't seem to find where to put it. It should be obvious, but I've got no clue and no good pictures. 

 

Thanks for any help. 

 

And for those keeping track of my project, I do still plan to convert this puppy to electric, but I've got a lot of homework to do first and would like to have a truck while I wait. 

 

[datzenmike]

1/ Maybe some pictures? But tube on carburetor??? Hose you mean? There is a float chamber vent hose that goes to the charcoal canister on California emissions trucks. EF & EC-90 has a diagram in the Evaporative Emissions Control System in the  '84 Factory Service Manual. I don't know about earlier California years.

 

2/ Brake booster isn't anything to do with emissions only braking... and it should be connected to the booster if you want to get stopped.

 

3/ There are no stupid questions only not asking. The hose from the wrap around heat shield is part of the automatic temperature control. (ATC) It connects to the stock air filter housing snorkel where a vacuum operated servo mixes air from in front of the radiator and the warmed air from the hot exhaust. A sensor in the air filter housing keeps the intake air tightly controlled at around 100F. The engine runs more reliably and fuel efficient (and pollutes less) when it thinks it's August all year. It's disabled under full throttle as the intake vacuum drops and the servo closes off the hot air for maximum performance.

[DIY 1985]

The booster hose runs from the booster to a barb on the firewall side of the intake manifold.

[datzenmike]

It should connect to the intake manifold.

[720_Daniel]

Here's some images. Sorry if it isn't the standard way to upload images. I just used Imgur. 

 

Image 1 is the vacuum diagram that's under the hood with the carb tube marked in red. That's supposed to go to the canister? The canister is all filled up, but I could put a T in there if that's what is needed. Also, the diagram doesn't show it, but there are two hoses coming off the canister. They're both passed along through the metal tubes bolted to the front of the block. I found a more accurate diagram somewhere, but it also didn't show the tube on the carb that I'm concerned about. 

 

The second image is the metal tube coming off of the carb near the float window. 

 

The third image is my exhaust. Maybe the exhaust isn't stock and that's why I can't find the place to hook up the pre-heater hose. Could someone pop the hood of their 720 and have a look? 

 

The last picture is the brake booster hose with the little red cap on it that looks like it is there in place of a vacuum hose. That's supposed to go to a barb in the firewall? 

 

Thanks again for your thoughts. 

 

https://imgur.com/a/aP1VTpX

 

 

 

 

[datzenmike]

 

 

If you had an automatic the line the red cap is on would be used.

 

 

That sure looks like the bowl vent hose but it's capped so may not be used on the earlier Z22 engine even if in California.

 

 

 

The ATC heat shield should look like the manifold on the left. Ignore the long bending EGR pipe, and the O₂ sensor with the green wire. It has a largish pipe on it (kind of rusty) that the metalized pipe connects to that sends warmed air up into the air filter housing.

 

[720_Daniel]

Ahhh! That makes sense. It must've been stripped when they removed the emission stuff. What silly people. 

 

Here's a manifold from ebay that has a pretty clear picture. I wonder if I can find that part or maybe just fabricate something out of aluminum. https://www.ebay.com/itm/224700726299?fits=Submodel%3ADeluxe|Year%3A1982|Engine+-+Liter_Display%3A2.2L|Model%3A720|Make%3ADatsun|Trim%3ADeluxe+Extended+Cab+Pickup+2-Door|Engine%3A2.2L+2187CC+l4+GAS+SOHC+Naturally+Aspirated&hash=item345134fc1b:g:pXgAAOSwJSdhltfK

 

 

I found one in Tokyo! Part number 16590-W110

 

https://www.ebay.com/itm/124869779525?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=124869779525&targetid=1493511175905&device=c&mktype=&googleloc=9032086&poi=&campaignid=15431381266&mkgroupid=128740829685&rlsatarget=pla-1493511175905&abcId=9300764&merchantid=6296724&gclid=Cj0KCQiAi9mPBhCJARIsAHchl1xQUfLOeWk3c-L2WHo2nFjjXCnsN4NoIb1kuaWSYJlrxwxJNRjUMfQaAqD3EALw_wcB

[DIY 1985]

Maybe, the bowl vent is supposed to go to a tee that runs to the charcoal canister and the thermal vacuum valve/distributor, as suggested on your emissions control hood diagram (not really a map or layout plan, just a diagram, so it isn't in front where you marked it's location)?

[datzenmike]

I cut one out of a Maxwell House coffee can for my 620 and stove pipe wired it on... till one came around. It will work but might not pass a visual inspection.

 

 

If this is the diagram for your emissions then the bowl vent is simply not used. Nothing from the engine goes to the canister except the vacuum signal to open and purge it. (it's also the distributor vacuum advance signal so if loose or disconnected you have no vacuum advance) It doesn't show the line that collects fumes from the gas tank or the purge line back to the intake to draw the fums in to be burned. The canister should have 3 lines to it.

[DIY 1985]

Does your engine use hard lines which route tubing from the intake side to the area by the distributor?

 

Actually, they are using oil filters for Maxwell House:

https://yotaoilfilters.com/products/toyota-oil-filter-vacuum-sealed-insulated-tumbler

[datzenmike]

I think all Z series did. The Z24 had three, vacuum advance, purge signal and vacuum from the intake. Earlier used the vacuum advance as the purge signal but this was later separated and run off the ported EGR signal which will shut off at idle.

[720_Daniel]

12 hours ago, DIY 1985 said:

Does your engine use hard lines which route tubing from the intake side to the area by the distributor?

Yes. It has 2 lines that run across the front of the block. Those were a pain to replace. 

[datzenmike]

 So a previous owner removed them????? Previous owners are idiots. The charcoal canister is absolutely benign in operation and has no effect on running. Removing it also removes the vacuum advance which WILL alter the running. So I guess you now have vacuum advance to your distributor?

[720_Daniel]

They left some of the vacuum parts in place, specifically the distributor advance and one line running to a port on the carb. But they did remove the hard lines that crossed the block. I'm amazed I found the parts in a junkyard. Amazed. 

[DIY 1985]

In defense of previous owner's, it gets confusing.  When you look at the sticker/vacuum diagram, and you see just one hose going to the charcoal canister, but the charcoal can has three barbs, that, and there is only one line illustrated for the AB valve, but the engine has a line going to the air cleaner assembly, and two going to the intake manifold (one to sense the vacuum, one to add a pulse of filtered air.  Plus, the previous owner was possibly digging thru work done by an earlier owner...

 

It is common to just install a vented fuel cap for dumbing down and simplifying during desmog.

 

Like mine, I discovered a float bowl vent on the carb that it came with, and it was routed to the charcoal can (five barbs - a purge signal line, two fuel vapor flush purge lines to a factory looking junction barb before the AB valve line to the intake manifold - iirc, and a line to the fuel tank).  But, the FSM describes no float bowl vent on the carb itself, just the canister.

 

 

Also, it is a 12/84 (USA) build (making it an '85 model year).  The FSM describes an air/fuel ratio solenoid in the carb, but it wasn't there when I found it.  Maybe the folks at the corner auto parts sold a rebuild of incorrect carb (I don't actually know what an incorrect carb would look like, but, I bet it would bolt up) to some pre-internet dude, back in the '90's, and took the original factory carb as a core?

 

BTW, you'll see above, that my emissions routing diagram correctly shows three lines from the AB valve, unlike the sticker provided by this thread's author.

 

 

[datzenmike]

There's no defense for removing emission equipment on Californian vehicles that are going to eventually need them to pass testing. Some poor bugger will have to find equivalent replacement parts in the future. The same bugger that paid a lot of money for the truck to find it's going to cost a thousand dollars just for that! If it was the previous previous owner they are still an idiot. This does absolutely nothing for the running of the vehicle and usually makes things worse. Though a federal offense in any state to alter the emissions equipment, outside of California no one checks so little chance of a problem. If disabled or removed properly anywhere else there are no inspections, it's not a worry. Some emissions equipment actually increase gas mileage and engine life.

[DIY 1985]

It happens.  For example someone trying to be helpful, suggests diesel-type of motor oil, in a gas engine vehicle, even though it isn't that type of catalytic converter compatible.

[720_Daniel]

I used some roof flashing and fashioned up a replacement part for the reheater hose. I'll let you all know if it passes smog. 

The truck is still running a bit rough. There was a glorious moment when I was half-finished and I took it to the parts store. It ran like a champ. So, I'm pretty sure I've got a little vac leak. I'm going to replace all the soft vacuum lines and double check the routing. 

 

Also, any suggestions on where to set the air/fuel mix? 

 

I found the correct emissions routing diagram that actually has the right canister and number of hard cross over lines.

 1982 Datsun 720 California vacuum routing

 

What image hosting service do you all use? I can't insert an image from imgur. Maybe it's my rookie status. 

 

Thanks again. 

[datzenmike]

4 hours ago, DIY 1985 said:

It happens.  For example someone trying to be helpful, suggests diesel-type of motor oil, in a gas engine vehicle, even though it isn't that type of catalytic converter compatible.

 

It's ok to use diesel oil in old Datsuns but not in newer 2000s engines that have the exotic new catalytic converters that don't tolerate the old higher levels of ZDDP in them. Our older 'flat tappet' engines need the higher anti scuff additive ZDDP levels from 40 years ago that's missing in today's oils. Only diesel oils still use it.

[720_Daniel]

Ooooh. A little too much shade is being thrown in here. You guys are both very flipping helpful. 

 

Update: I had misrouted the vacuum coming off the carb/thermal valve T. It's running much smoother. Still a little sluggish, but that might just be the 350,000 plus miles on the car. 

 

When I rev and shift on the quick, I get a tiny bit of backfire that seems to be proportional to how long I have the RPMs up at 4,000 or so. I'm not sure how to diagnose that, but I'll try and figure that out before I go pay fealty to the smogman. 

[datzenmike]

Exhaust backfire? There is an AB valve (anti backfire) that reduces this so it may go away once everything emissions related is complete.

[720_Daniel]

Right. After I posted that, I read a lot that you had posted about the AB valve. This vacuum system is really smart.