EGR Delete on a 77 L20b, stock hitachi carb.

[280zx2by2]

I searched and couldn't find any real relevant info, The pipe is already removed by PO and blacked off, the erg ststem also seems to be filled with rust and some other crap (its epic filled, I was like "OMG" Ya know)

 

 

I see there are several lines that attach from the end of the ERG, what do they do?

 

 

I mean it the ERG isn't functioning I don't see why I would need to worry about them in the first place.

 

 

PS: Where is the PCV valve at on these?

[Braden]

its easy dude, you need to locate a non smog set of manifolds. i did the delete on my 77 620 non cali model. pcv valve is located where the pcv hose comes out of the block and routes into the intake. whe you say egr what you really mean is egr as a whole, there are many different components that make it up. you need to remove the air pump, charcoal canister, and basically everything that is attached to the manifold side of the block, once you have all of that off the only thing you put back on the block is your non smog manifolds, and your carb, hook up the large vacumm line to your brake booster and your vacumm advance line and your done!!! here is a picture of what mine looked like back when i had my old engine and i did the egr delete.

and here is what it looked like before.

good luck and if you have any more questions feel free to ask

[datzenmike]

The PCV is vital and should be kept. If using a block off plate weld a bung on that the PCV valve can screw into.

 

Easiest thing is to leave all EGR alone so there are no leaks and the PCV functions and just remove the hose. On the valve cover side of the carb are two hose fittings. The front goes to the vacuum advance, the rear goes to the EGR system. Depending on year it may first go through the thermal vacuum valve (TVV) on the thermostat housing (allows EGR only when motor is warmed up) and/or through the back pressure transducer valve. (BPT) EGR varied to match exhaust pressure. Any hose removed will stop EGR. Plug the return to carb side.

 

The crap in the EGR is combustion by-products from the exhaust manifold. These can build up around the EGR valve and prevent it closing. This is fine at highway speeds but is a small vacuum leak that will affect the engine running at idle. Wire brush the valve clean and install.... good for another 30K.

[Braden]

good advice mike, correct me if i am wrong he is trying to "pretty" up his engine bay? mike is right you need your pcv valve or atleast you need to put a filter on it if your not going to route it back into the intake. the pcv isnt really a part of emissions its to vent moisture and explosive gases from your crankcase. if you look at one of the pictures of my newer manifold there is a steel block off plate with a 90 degree pipe fitting on it, this is where my pcv connected.

[datzenmike]

I would say that it IS part of the emissions system as it burns, or at least 'recycles' unburnt hydrocarbons and oil that blow by the rings. But it's keeping the inside of the engine clean that is way way more important. It was introduced around '62 and I don't think emissions were a high priority back then but cleaner longer running motors with fewer oil changes were. Reducing emissions was just a side benefit.

 

The charcoal canister collects fumes from the gas tank and hot carb fuel bowls when shut down and 'saves' them from escaping into the air to add to the smog. Next time the motor is run vacuum draws them into the intake to be burned. Costs nothing, simple in operation and has zero effect on running.

 

I think the '79 620 and all 720s have a fuel shut off system using the idle cut solenoid. When decelerating at high speed the extreme vacuum will cause a rich mixture to be sucked in through the idle circuit and blown directly out the exhaust pipe. Using a vacuum valve and switch, the idle cut solenoid closes off the idle circuit until vacuum levels lower. Gas is actually saved and pollution reduced. win win.

[Spades]

If you can't locate a set of non smog manifolds(I know for my Naps motor it wasn't really an option), Napa or another auto parts store should have an assortment of oil and transmission drain plugs, the thread sizes for various plugs were the same thread pitch as the EGR fittings on my naps intake manifold, and they make a clean looking plug off for the EGR stuff. I just used some high temp Teflon thread sealer and popped them in.

 

For the exhaust manifold I had to order a high temp bolt in special from Fastenal though, no one local had the right thread pitch for the exhaust manifold outlet for the EGR(in a grade 8 or better high temp version anyway).

[datzenmike]

Could I run the crank case ventilation hose into a catch can or does it need the vacuum of the intake manifold?

 

You could but I thought you wanted an uncluttered look. :D Try to return it to stock operation. The PCV has a tiny hole and one way valve and at most speeds will draw water vapor, oil and gas fumes and combustion by products that squeeze past the rings and run them through the motor again to be burned up. All these things if left will condense inside the motor when it cools down, specially short trips in the winter. All these things will contaminate your oil and reduce it's lubricating properties and it will need changing more often.................................................................... the smog nazi

[Spades]

Yeah, I kept my PCV system...I had to replace all of the tubing cause it was all cracked, but that is one of the systems I kept. I used a breather on the valve cover though, so far I haven't had any problems with that.

 

The drainplugs will look a little better than standard bolts will, and will look WAY better than welding the holes up. and because they are shallow to begin with, you shouldn't have to cut them to fit. Not to mention that since I used aluminum plugs, they look like a factory-delete option. So far no one looking at my engine has even noticed that my motor used to have an EGR system.

[Spades]

EGR stands for Exhaust Gas Recirculation. It is supposed to recycle some of the cars exhaust at certain times. The EGR valve controls when the exhaust gasses will enter the intake manifold. When it is properly operating, contrary to what most people think, it will not hurt performance, because under full acceleration, the EGR will not be shoving exhaust through the intake. Basically, EGR is a way to help control emissions by feeding exhaust back through the motor, this helps clean up the exhaust by giving a second chance to light off unburnt fuel, ect.

 

It is kind of a trade off, because lower combustion chamber temperatures makes for more horsepower and better fuel mileage, but the higher temperatures caused by feeding hot air into the motor reduce the noxious emissions produced by a gasoline motor. The EGR system picks when to drop the recirculated exhaust to give the motor decent efficiency and the cleanest emissions.

 

I have my EGR plugged off, with no catalytic converters, and yet my car is still clean enough to pass Portland area DEQ standards for vehicles produced after the year 2000. Go Naps Z! Technically my car is smog exempt by year, and because I live in a non DEQ area, but its nice to know my car still is a clean little machine.

 

If you are going to delete it, just go all the way, and block off any ports on the carb and intake manifold, and remove the complete EGR set up. Make sure that you leave any lines from the carb going to the vacuum advance of your distributor, or anything required to make the choke work, ect. The rest of it though I just removed and boxed up in case I ever wanted to put it back on, and used aluminum plugs on the intake manifold, blocked off carb or other vacuum ports with rubber vacuum caps, and a steel bolt on the exhaust manifold.

 

P.S. yeah, the build up in the EGR system is most likely a carbon based buildup, it happens. On older cars the EGR valves were very prone to clogging open or closed, which would throw off the tuning of the motor, since the ignition and fuel were calibrated for a functioning valve.