71 521 removal of all smog components

[katfish]

going to the well once again   my 1971 521 is a transplant from calif had all the smog devices, Ive removed the pump but there are still hoses and pipes that once had hoses on them manly the exhaust manifold  I need to know what can i remove and what needs to stay or be plugged Thanks 

[d.p]

I got a pic in my thread somewhere.  But whatever was connected to the pump you can remove.   

[katfish]

that pic would surely help if you can find it but if not what needs to be plugged for it to idle correctly 

[datzenmike]

Put the year of your 521 in your profile as it will save asking later. I don't think there was much for emissions equipment even on the California truck. Be sure to keep the PCV valve operational. The distributor probably will have dual points. One is set to open about 4 degrees later or retarded under certain conditions of temperature, clutch and transmission gear position. Unplugging the relay that controls the on and off of these retarded set of points will disable it. 

 

As mentioned the smog pump and anything connected to it can go. Cut the pipes off the exhaust manifold and use a socket to remove the tube and nut that goes down inside the exhaust port. Take one of the threaded nuts to a fastener shop and get 4 of these to seal the holes... Probably metric pipe.

 

 

 

[mainer311]

The air injection ports on the exhaust manifold are M14x1.5 metric straight threads. (Same size as most oil pan drain plugs.) In the meantime, you can cut the tubes, crimp them shut, and then fold the end over a couple times to seal them off.

Edited December 8, 2021 by mainer311

[Stoffregen Motorsports]

The only thing that engine needs is a source for vacuum advance on the distributor. If you want to get a bit snappier throttle response, then you can even delete that and re-curve your distributor.

 

The one item I would leave alone is the hot water pipe that runs from the radiator inlet to the intake manifold. The "hot" water there actually helps cool the intake once the engine is hot. Other than that, delete everything!

 

A PCV valve and associated plumbing will help the engine oil stay in the crankcase, but it too can be deleted. I have run the two breather hoses teed together and stuck into a grommet in the under side of the air cleaner housing. This helps with the oil vapor and deletes the PCV valve.

[datzenmike]

Keep the PCV valve. Although technically an anti pollution device it's biggest advantage is extending engine life. It draws filtered air through the crankcase removing water and combustion vapors that would condense over night diluting and contaminating the engine oil. It has no effect on running, does so much for your engine, and asks nothing in return. Besides, it's already there and working so you don't have to do anything but leave the little guy alone. 

[katfish]

its a 1971  521  im a little slow on the up take (me) not the car so much but ill get the plugs and slow walk the info, is there a filter that goes on that pcv   ill keep you posted thanks for the pictures and info 

[datzenmike]

No it connects to the stock air filter. Under certain conditions flow is reversed and the fumes are directed inside the air filter where they are sucked down through the carburetor and burned. I know the little blue filters are very trendy and cute, but the fumes just empty into the engine compartment and enter the cabin. Also any oil just drips off it onto the engine. Trust the original design.

[katfish]

thanks much obliged 

[katfish]

got that smog device out today  the flange nuts and the tubes where so fragile they broke off the metal was made of a soft type metal so i couldnt bend them   so what i ended up doing because the metal was so soft  i took self tapping bolts  and screwed them in  looks good  so thanks to you all for the knowledge and support