smog crap

[mypos620]

my 76 has all the smog crap on it what to i need to do to get it all out of there? theres so much stuff in there i dont know where to start!

[Guest DatsuNoob]

I'm hearin ya, I just dealt with the same damn thing. I got a 76 as well. First start by disconnecting the anti-backfire valve at the rear of the carb.(I think that's what it's called) It's the thing with the hose running to your air cleaner.Next unbolt the stock Hitachi carb, and.. are you ready? Throw that fu*kin' piece of trash as hard and as far as you possibly can. Then go to your intake manifold and remove the 3 bolts holding the air pump on the side of it. You will need to fabricate a block-off plate with some of that "do-it-yourself" paper gasket material behind it to block off the 2holes that lead into the intake ports(I was thinking this would eventually be a sweet spot to run a port and line for a dry NOS fogger). Get a step bit and drill them out to fit. Your plate doesnt have to be anything crazy thick, but I like overkill, so I hacked a piece off my homemade diamond plate bumper with a sawzall and a 9" bi-metal blade(it looks cool too :D ). Take out those studs and replace em with bolts. Take that same sawzall and cut all copper lines running between the manifolds and crimp them by rolling them down like toothpaste tubes and pinching the ends. Replace your carb (after capping any unneccesary vacuum lines) and that should get you started. Good luck

[Guest DatsuNoob]

Oh, I forgot something, a cool tip for making your paper gasket for the block-off plate. Take that air pump that came from the side of your intake and smear a tiny bit of oil on the face of it with your finger, next take your gasket paper and press it firmly around the edges, take it off and you have a perfect imprint to cut out with an exacto or utility knife. This technique will work for any gasket you have to make.

[OL YELLER]

When you finish trashing the Hitachi Carb..fish it bac k out and send it to me..I will pay you to ship it to me...I have the stock carb on Ol Yeller, been that way for 30,000 miles, runs like a top and gets between 29 and 30 mpg.....dude send that sucker to me!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! no trash can for that one......

[datzenmike]

my 76 has all the smog crap on it what to i need to do to get it all out of there? theres so much stuff in there i dont know where to start!

 

I'm hearin ya, I just dealt with the same damn thing. I got a 76 as well. First start by disconnecting the anti-backfire valve at the rear of the carb.(I think that's what it's called) It's the thing with the hose running to your air cleaner.Next unbolt the stock Hitachi carb, and.. are you ready? Throw that fu*kin' piece of trash as hard and as far as you possibly can. Then go to your intake manifold and remove the 3 bolts holding the air pump on the side of it. You will need to fabricate a block-off plate with some of that "do-it-yourself" paper gasket material behind it to block off the 2holes that lead into the intake ports(I was thinking this would eventually be a sweet spot to run a port and line for a dry NOS fogger). Get a step bit and drill them out to fit. Your plate doesnt have to be anything crazy thick, but I like overkill, so I hacked a piece off my homemade diamond plate bumper with a sawzall and a 9" bi-metal blade(it looks cool too :D ). Take out those studs and replace em with bolts. Take that same sawzall and cut all copper lines running between the manifolds and crimp them by rolling them down like toothpaste tubes and pinching the ends. Replace your carb (after capping any unneccesary vacuum lines) and that should get you started. Good luck

 

Gentlemen,

first let me say, that it's easier to keep the EGR system working properly than to take it off. If it's the 'trendy thing to do', OR you want an 'un-cluttered look' well that's up to you, but I've yet to see any claims of performance or economy gains from this. You wouldn't take your appendix out because it might cause trouble later, right? And what about your PCV valve that also connects to the EGR manifold you removed? Where do you hook that up to now? Well, if you've made up your mind, read no further.

 

The EGR is a valve on your intake, and if it doesn't close properly, it will act like a vacuum leak and performance (a little) and idle will suffer. Usually this is caused by carbon deposits that can be brushed off to fix... easy.

 

The EGR valve is closed by a spring in it's rest or off position and requires a vacuum source to open it. Disconnecting this source is the easiest way to disable the EGR from working and its removal and making a cover plate and gasket and removing the exhaust stove pipe and crimping, is, (besides being un-necessary) way too much work. It may also be illegal to modify this system, and difficult to find the parts to put it back in working condition. As I said, it's easier to keep it, just disconnect it. (well plug one of the vacuum lines actually), that way visually, the system appears intact.

 

Which brings me to, why disconnect it at all? If it's working, you can't tell, it's only if it fails to close properly that there may be problems.

[OL YELLER]

yeah....what he said...............seriously, great post Mike. That is the most logical explanation I have heard in a long time..way to go...

[dat521gatherer]

i just did mine in the last two weeks. i removed my manifolds to start from scratch. start by making some room in there. get rid of that black canister and that giant blue round thing. take off the pump itself. i removed all 4 pollution pipes from the exhaust manifold and put 14x1.5 bolts in. yes all 4 came out!! the l16 manifolds are 14x1.5 on my l16 only 1 came out and i drilled the other 3 out. the pipe on the bottom of the exhaust manifold i tried to unscrew but ended up drillind and putting a 14x1.5 after taping the hole. take off that ugly fuel rail pipe and put a single hose from the fuel pump to the carb. cap off the 2 other lines 1 being next to the starter and the other under the master cylinder.you may want to keep the 2 brackets next to the carb, one being for the carb return spring and the other being the throttle cable mount. when removing the 4 pipes from the manifold chop the lines off with a dremel or sawsall then you can stick a socket on them. use lots of wd-40 and work them back and forth and don't try useing a wrench. while taking off my manifolds i broke the 3 down/header pipe bolts and had to drill those out. if your ever buying drill bits stay away from the cheap titanium wal-mart and get the cobalt ones. as far as the block off plate for the side of the intake i am just useing a block of wood until i can find a piecre of sheet metal. i also scrapped the manifold drip plate and heat shield. now if you decide to take off the manifolds you may not be able to get to the lower intake bolts. so i undid the 4 connecting center manifold bolts that hold the 2 manifolds together and pried the intake up and off. thank god the gasket is thick enough to do this without scaring the head. i'll try to get some pics later tonight. (where to start) that was my first thought. i finished mine last night and now need the wiring harness from the ballest forward. maybe you could get a pic of that for me. i'm kinda stuck not knowing where the wires go. it was dizzed and then undizzed. and i've lost the wires from the coil to the dist. crap!!

[datzenmike]

Thanks Ron. Relatively speaking, the L 'smog crap' is fairly simple compared to the 720's but can seem like a basket 'o snakes to some and I understand their frustration. I just think it got a bad reputation and everybody blames it for everything and the popular thing to do is rip it out. I have put half of the 300,000 Km on my truck and I just check the hoses and connections, everything is there (came without an air pump) and it's never caused problems. If it works, don't fix it!

 

My dad,s '64 Dodge had a PCV system on it, that's all! Even my '70 340 only had that and idle screw adjustment limiters. The early systems were reactive, doing what it could as you drove along. Now-a -days these systems are very pro-active (computer and sensor controlled) and they decide what you can do with the engine that it not stray outside it's pre-set pollution limits.

[datzenmike]

dat521gatherer

 

You seem to have, by your description a pre '78 L20B, and if you do, the fuel rail probably has a return line to the tank and there are two good reasons for leaving it hooked up this way.

 

First, without it the fuel sits in the metal line outside the carb and can boil from the extra heat the L20B makes and cause a vapor lock condition in the carb, resulting in hard restarts when the engine is warm. There is a small restriction in the return line to keep the pressure from the pump up but still allow circulation of cooler gas from the tank. Second the fuel is constantly being circulated through the fuel filter and crap doesn't build up in the tank.

 

The black canister is for storing excess gas fumes from the gas tank and the carb and then feeding them into the intake when the engine is running. It in no way can affect performance and is harmless.

 

Your wooden block off plate... You don't mention what you did with the PCV valve and hose that were mounted there. This is another system that has no effect on the performance and actually it is to your advantage to have it hooked up as it removes warm unburnt gas and oil fumes and water vapor from the crank case and burns them. Without this they condense inside the motor and contaminate the oil and bearings.

 

You mention removing the manifold heat shield. Did you mean the pipe that supplies warm air to the air filter during warm up? If so keep it. Living in Washington you'll need warm air on cold damp days to prevent carb icing. Trust me on this

 

Go to .http://www.the620.com/ Look under 620 tech down near the bottom there are wiring diagrams for '75to '78 620 trucks.

[datsunaholic]

If he removed the flex pipe he probably has a weber to begin with, so no where to put it since the stock air cleaner went away too.

 

However, I echo the idea of leaving the stock 2-line fuel rail in place. For one, if you use an electric fuel pump, the pressure is too high for the float valve and the carb floods. I've had this happen on 2 trucks that had the fuel rail removed and just had a long hose from the filter (down by the starter!) to the carb. You really want as little hose as possible. To counteract this I see many, many Datsuns with fuel pressure regulators. This is somewhat required on 1973 and older ones that don't have return systems, but on '75 and later it's a very, very good thing to have. I restored the return lines on all 3 of my weber-equipped, electric pump 620s (all 3 were capped when I got them) and the flooding stopped on 2, the vapor lock stopped on one, and the constant line fouling stopped on the third..

 

Now, one of my trucks DOES have the EGR manifold removed and a block off plate in its place. BUT... the block off plate has a angle fitting installed which holds the PCV valve, which remains in place. As Mike said, having No PCV will cause the internals to break down faster- water vapor forms acid in the engine. Plus, you build up excessive pressure in the crankcase, which over time will blow out the valve cover and oil pan gaskets or the main seals. That fitting on the top of the valve cover is an air INLET not an outlet. Without the PCV, there's no circulation- the only inlet is blowby, which is volatile, and if you've ever seen a crankcase explosion (I have) you'd want to keep those gasses out of the crankcase.

[dat521gatherer]

my exhaust plugs came out so easy it was sick.

[dat521gatherer]

the wood block is temporary till i find a piece of sheet metal. i've had straight fuel lines hooked up to my hitchi 328 340 and weber and never had a problem. i did replace a float shut off valve once cause of flooding and it fixed the problem right away. you cant expect a spring that small and old to last soaked in fuelafter 30-35 years. although i dont deny other people have major problems with this. i personally have had no problems. i think the fuel pump only puts out like 3.5 psi.

[datzenmike]

As I said mine came with the pump removed. The P/O had cut the metal air lines about 2" above the ends and curled them up to stop any exhaust leaks but it looked like hell. I got a pipe wrench on the very back one and got it out, the tube goes way in by the valve in the port where the exhaust is hottest, I plugged the hole with a metric pipe plug. The other three were too hard to get at at the time and I just left them, figuring to do it if I ever take the manifold off . Yours is a pre '78 exhaust and maybe mine's harder to do. Speaking of pre '78 L20B's, your's uses the hot exhaust to warm the under side if the intake manifold.There will be a spring loaded valve on the outside of the exhaust manifold below the throttle cable, make sure it isn't seized up, or sticky as this will cause hard running when the motor is cold.

What did you do with the PCV valve and hose?

[Guest DatsuNoob]

Why not just use a breather cap on the valve cover or one of those small K&N style filters where the hose would go to the air cleaner? Old school V8's used the same thing without PCV's and it wasn't a problem, I dont get why you couldn't get away with using one to vent an L20B. All that EGR crap was intended for was making sure all crankcase and exhaust fumes travel out of the tailpipe. The govt didn't want any fumes to be let out into the air from under the hood, but on a vehicle this old(without emissions laws applying) who gives a rat's posterior?

[]2eDeYe]

Why not just use a breather cap on the valve cover or one of those small K&N style filters where the hose would go to the air cleaner? Old school V8's used the same thing without PCV's and it wasn't a problem, I dont get why you couldn't get away with using one to vent an L20B. All that EGR crap was intended for was making sure all crankcase and exhaust fumes travel out of the tailpipe. The govt didn't want any fumes to be let out into the air from under the hood, but on a vehicle this old(without emissions laws applying) who gives a rat's posterior?

 

 

PCV = POSITIVE CRANKCASE VENTILATION....

 

This has almost nothing to do with emissions...

Most old school V8's still have some sort of ventilation...

My 56 chevy has a tube pointing at the ground...it will be getting a pcv system when it goes under the knife.

My 72 Jeep has a PCV valve and it's staying.

 

Without positive air flow thru the crankcase you will blow seals or something else will happen (usually worse than a blown seal). :eek:

 

The valve cover is the air inlet and the pcv is the outlet...without the pcv valve there is nothing to pull air through the inlet.

I don't get why you don't get it....:rolleyes:

 

...Personally, I give a rat's posterior if my vehicle is dumping oil on the ground and I rather not breathe in the air from my crankcase as I'm driving down the street ;)

[ramseys21]

its illegal to remove to tamper with any emission control device on a vehicle. its also illegal to put an engine in a car that it did not come with for that model year. yes its illegal just not enforced. at least in the great state of California it is. i say leave the stuff on. the egr doesnt even work at high loads. when i do my sr i will have all the smog stuff on and will probably run a cat.

[datzenmike]

Why not just use a breather cap on the valve cover or one of those small K&N style filters where the hose would go to the air cleaner? Old school V8's used the same thing without PCV's and it wasn't a problem, I dont get why you couldn't get away with using one to vent an L20B. All that EGR crap was intended for was making sure all crankcase and exhaust fumes travel out of the tailpipe. The govt didn't want any fumes to be let out into the air from under the hood, but on a vehicle this old(without emissions laws applying) who gives a rat's posterior?

 

 

We've covered this before. The biggest problem with 'smog crap' is people's ignorance of how they work, how to keep then working and mostly how easy that is. The L's 'smog crap' is totally re-active and has little effect on performance, not like the pro-active computer/sensor controlled systems of today that tell the engine what it can or cannot do to keep emissions within pre set limits. If you think your motor will gain any hp from it removal you are dreaming. If it runs better it's because you didn't keep the system working properly in the first place. Besides being illegal to tamper with, it's easier to fix and maintain than to spend hours tearing it out and fabricating block off plates. Removing it to make it look un-cluttered is a bit lame.

 

PCV valves started being put on cars around '62. One of the smartest ides ever. Prior to this there was a breather pipe from the crank case that pointed to the ground and sometimes a screened filter on the valve cover where you put oil in, that was it. No way to move the fumes except for blow by pressure. At night the warm water vapor and unburnt gas and oil fumes condense inside the motor, diluting the oil and forming a sludge on all the surfaces. Is it any wonder that these older motors lasted 70-100K miles?

 

Enter the PCE valve. It is a small opening into the intake, but not big enough to affect idle or running. In it is a one way spring loaded valve that is opened by vacuum, and draws crank case air, along with blow by, unburnt gas, oil fumes and water vapor into the intake to be burned by the motor. Why a one way valve? Because if the engine should back fire, you do NOT want a flame traveling down into the crank case and possibly igniting any gas fumes!!! I've seen this happen to a non PCV car that was flooded, the explosion blew the valve cover off, denting the hood, and bent the oil pan, not good!

 

Besides keeping the engine oil cleaner, which vastly extends friction surfaces and bearing life there is an added benefit. The crank case is kept at a slightly negative air pressure, which means that air is trying to get in, which means that oil has a harder time leaking out past worn seals and gaskets!

 

The PCV valve has NO effect on running performance, it just tags along and does so much good. Extends engine life, cleaner, low risk of crankcase explosion and environmentally friendly for the cost of some hose and a $5 valve.

 

You say: 'All that EGR crap was intended for was making sure all crankcase and exhaust fumes travel out of the tailpipe'. I'm sure you meant PCV not EGR as the EGR has nothing to do with fumes. A properly functioning EGR valve has no effect on idle because it is not operating. It has no effect on a cold or warming up motor because it is not operating, and has no effect on high speeds or full throttle because it's not operating, so the rest of the time it's along for the ride and doing it's job un-noticed by the driver.

 

You say:' but on a vehicle this old(without emissions laws applying) who gives a rat's posterior?' Well the emission laws do apply. If it came with PCV, EGR, A.I.R. injection, BCCD etc., it is illegal to remove, tamper or modify them. Be thankful you don't drive a newer car.

 

ramseys21, Could not agree more. Some newer cars might run better without 'smog crap' but not the L . Well, when their motors don't run right they'll have to fix the problem instead of blaming the EGR.

[datsun76_620]

I have yet to really check into DCOEs....I'm working a DGEV motor 1st...but...

 

I have yet to see any PCV valves/connections on the weber manifolds. (cannons mostly)

 

I know the Aussie 1200 folks are running oil catch cans....

 

...please educate me!

[datzenmike]

I have yet to really check into DCOEs....I'm working a DGEV motor 1st...but...

 

I have yet to see any PCV valves/connections on the weber manifolds. (cannons mostly)

 

I know the Aussie 1200 folks are running oil catch cans....

 

...please educate me!

 

The catch can is to prevent oil from a lunched motor from spilling on the race track. Not necessary on a street car unless you smoke your motor regularly. lol

 

Some manifolds may not have a PCV port but many carburetor bases do. My wife's 318 Plymouth's PCV hose goes into the bottom rear of the carb. The laws for a street car don't apply on the race track and performance manifolds don't have to have smog connections on them because of their intended use on the track. Still, some of them end up on street cars and technically have to have the smog equipment they were built with. What you do is your own business, but I would run a PCV valve mostly because of it's benefits to engine longevity. How hard can it be to drill and tap a hole and mount one?

[Guest DatsuNoob]

okay, okay, you got me, but jeez, help a dude out here, please enlighten me instead of illustrate my ingorance :o hahaha. So then the question is how do I mount a PCV to an L16 intake manifold after removing the stock L20b one so I can use a replacement carb and header? Just didnt know how to do that, needed to replace my carb, and got a good deal on a header.After seeing that both my intake and exhaust manifold were mated together, removing all that junk seemed like the easiest solution. Could someone please explain or possibly show me a picture of what to do about installing a PCV on an L16 manifold? Thanks guys

[datsunaholic]

The mated manifolds weren't an emissions thing. True, they had the air injection system and the EGR, but the reason they were bolted together was to "Stovepipe" them to heat the intake to prevent carb icing. L16s, L18s, and '78+ L20Bs used water to heat the intake. It was just the '75-77 L20Bs that had the mated design.

 

As for the PCV...

 

The stock L16 intake manifolds- all of them, both the sidedraft (non-US) type and the downdraft type- have a port for the PCV.

 

I put a L16 mani on an L20B, and used the stock L20B PCV hose. It all lined up perfectly.

 

 

It's quite possible you're missing something. The stock L20B PCV tube (from the block) looks like this:

 

 

That's with the hose attached, but you get the idea.

[ramseys21]

this is a really good thread. haha

[Guest DatsuNoob]

my vw GTI had a PCV on the valve cover. It just looked like a white plastic elbow with a rubber sleeve fitting over it. Would it be possible to use a similar setup for an L20b? It looked pretty simple. Maybe even get a VW one and put it on my valve cover? Would that work? Don't really know, any help would be appreciated. Thanks.

[datzenmike]

Thanks for the pictures Doug. Don't want another long winded post so soon!!

 

The valve cover is where the fresh air goes in and would normally be connected to the air filter, to keep dust and dirt out of the motor. The PCV valve should go on the end of the hose coming from the crank case and be mounted onto the intake vacuum source.

 

If you've removed the stock L20B manifold you could use the PCV valve on it on the L16 manifold.

[RB_Shaggs]

Stupid question but i have one of those L16 manifolds in the pic and was gonna put it on my L20 but where do i mount my throttle linkage on it, since it doesn't have mounting points???