Discussion in 'E9 General Discussion' started by scottevest, Aug 2, 2017.
the e12 USA 5 series did not use a cat. not until the e28 did cats show up on the m30 engine.
Thank you so much for your thoughts and opinions. What would you do?
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I would remove the smog equipment but don't expect some big improvement in performance, it may be moderate. The coupes don't have a lot of stuff, principally the EGR and plumbing to the exhaust manifold which will need to be plugged. The dashpots on the firewall control advance/retard activation at different throttle situations.
To put some historical context and arcane trivia into the discussion, by the early 1970's California required smog inspections for DMV registration purposes on all American make cars 1955 and newer, and all Foreign make cars 1965 and newer. Cars with small engines (below 1000cc), and diesels are examples of cars that were exempt. For the most part this meant installing a PCV valve and closing off road draft tubes for those cars built before PCV valves were factory installed. In the mid 1970' s State law was amended to require retrofitting approved NOx control devices on nearly all 1966-70 year model cars. Approved devices included one that consisted of two rubber plugs to close off the vacuum advance, retarding the static ignition timing, and decals warning the driver not to exceed a certain speed. This program was ill conceived, technically flawed, and was discontinued part way through the one year implementation cycle. Occasionally one comes across a 1966-70 year model car with evidence of being once fitted with such a device. One might argue that the repeal of the NOx program allows the car owner to legally remove the NOx device without risking penalty.
At present, while 1975 and older year model cars are exempt from smog testing for registration purposes here in the Golden State, consider that our elected officials who generally vilify internal combustion engines can always try and change the law pushing back the exemption age to include cars presently exempt. Consider further that cars registered in metropolitan areas are required to be inspected every other year while cars registered in rural counties are generally not subjected to that requirement.
For 1976 year model and younger cars, when an engine is replaced with one from a different car the newer of the two engines will dictate what the Smog Referee Station will require to pass certification, to the extent that a replacement engine block can be identified by cast/stamped date codes.
As stated above, independent of California law, the Federal Clean Air Act does prohibit removal of factory installed emissions equipment from any year model car.
Lastly, from time to time someone floats the idea of installing road side sniffers as a way to ferret out gross polluters on the basis of actual emissions in low air quality areas. If such a Draconian measure were to ever see the light of day, I would expect that enforcement would involve an administrative process where the "offending" car is actually inspected and run through the traditional smog certification process with reinstallation of the removed emissions equipment and civil penalties being part of the outcome.
Based upon your information, it seems like it would be crazy for me to uninstall anything.
Like many things in life, it is a matter of weighing the options and deciding whether or not to assume the risk. Once you satisfy yourself as to the particulars in Idaho, do what you are comfortable doing. Keep any removed equipment so it may be reinstalled if needed in the future.
If the performance enhancements are only minor from removing it there seem to be no benefits whatsoever of doing so as I understand it. I really appreciate everyone's input here. I need to become a site donor given all the valuable information I am getting from this site. This afternoon I intend to call all of the Boise shops The claim to do carburetor work
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The benefits of removing the emissions are not just performance related which Chris mentioned are miniscule. The best reason to remove is to lower the operating temp of the engine, especially at idle. The retard function is used as a band aid to increase the temp at idle to burn off any noxious gas so as to pass the inspection test. Increased temp puts stress on our delicate aluminum cylinder head and other parts so it is not without risk or cost to keep them on. Removing will also improve idle quality as it will not be running leaner than the engine wants. These cars are not environmentaly friendly, removing the "emissions" stuff won't make them any less so after 45 years of leaks, inefficiencies, dripping oil, diff fluid, tranny fluid etc.
And you may find one that will be happy to remove your 74's emissions equipment. The risk to them is small, but not zero.
The alternative is to remove it yourself and retain the components. If you pass the components on to the next owner, and explain what was done, the risk to you should be small (but again not zero).
Are you suggesting that our fine politicians might pass laws that only serve as "window dressing", and not accomplish anything tangible? I'm shocked!
Just dive in... any decent mechanic with carb knowledge can tune a set of Webers and just have them pull the smog at the same time. It would drive me crazy to have it under my hood doing absolutely nothing to improve performance or keep the air clean.
Smog patrols are on the prowl
An AQMD pilot program uses roadside monitors to test emission levels. It may be the face of crackdowns to come.
If you think your everyday exhaust fumes are a private matter -- maybe your dirty little secret -- you haven't met up with Southern California's new pollution detectives.
In recent weeks, an innocuous white van has been parked on a Los Angeles freeway onramp, as well as other key locations across the region. Inside is new technology in the battle for cleaner air.
The van is loaded with high-tech equipment that uses ultraviolet and infrared sensors to measure the amount of pollution spewing out of the tailpipes of passing cars.
But it isn't recording license plates, they have been doing this for several years.
As others have mentioned, the major piece of emissions-related hardware is the EGR (exhaust gas recirculation) system. There is a good likelihood that yours is plugged or non-functional and therefore has little impact on engine performance other than extraneous weight. If the EGR valve were to stick in an open position and the exhaust manifold feed tube connection is open/unplugged, chances are you would notice a rough running engine. Some later models were fitted with thermal reactors bolted to the cylinder head that were intended to operate like catalytic converters. Of all the emission control hardware that could be detrimental to engine performance and longevity, these thermal reactors were probably at the top of the list. From what I gather, your engine is not so equipped.
As indicated by the diagram below, the remaining "controls" include carburetor jetting/settings and ignition timing modifications, all of which could be dealt with by most competent mechanics with simple hand tools. Using the European model for comparison, it can be argued that the biggest impediment to improved performance on your '74 North American engine is reduced compression. The Euro model had slightly increased compression (9:1 versus 8:1 ), resulting in slightly increased torque and horsepower.http://www.e9coupe.com/faq.html
Virtually all stock engines from the early '70s could benefit from some mild tuning tricks and most of those stock engines that are still on the road could probably benefit from a valve job and and new rings. However, even the lowest compression M30 engine provides more than adequate torque and horsepower for daily city and highway driving.
Thanks for all the information
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