katfish Posted December 7, 2021 Report Share Posted December 7, 2021 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 Quote Link to comment
d.p Posted December 7, 2021 Report Share Posted December 7, 2021 I got a pic in my thread somewhere. But whatever was connected to the pump you can remove. Quote Link to comment
katfish Posted December 7, 2021 Author Report Share Posted December 7, 2021 that pic would surely help if you can find it but if not what needs to be plugged for it to idle correctly Quote Link to comment
datzenmike Posted December 8, 2021 Report Share Posted December 8, 2021 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. 1 Quote Link to comment
mainer311 Posted December 8, 2021 Report Share Posted December 8, 2021 (edited) 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 1 Quote Link to comment
Stoffregen Motorsports Posted December 8, 2021 Report Share Posted December 8, 2021 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. Quote Link to comment
datzenmike Posted December 8, 2021 Report Share Posted December 8, 2021 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. 1 Quote Link to comment
katfish Posted December 8, 2021 Author Report Share Posted December 8, 2021 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 1 Quote Link to comment
datzenmike Posted December 8, 2021 Report Share Posted December 8, 2021 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. 1 Quote Link to comment
katfish Posted December 9, 2021 Author Report Share Posted December 9, 2021 thanks much obliged Quote Link to comment
katfish Posted January 6, 2022 Author Report Share Posted January 6, 2022 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 1 Quote Link to comment
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