Hello. I recently decided to attempt to install some headers to my 250. However there is currently two metal tubes which are connected a thick one (pictured below beginning on the bolt furthest to the right on the current header and looping around)and a slim one(is it in the first picture in the sleeve top right) Both lead to segments in the carb. Are they part of emission regulating parts which I can cut or will I have to hook them up to my new headers? My new headers don't seem to have some of the same attachments as the old one son regards to tubes leading to the carb, can I also leave these ends open on the carb such as the one pictured below in the second picture? Thanks
That's part of the emissions system, not needed unless your in a state that requires it. You need to plug off the ends at the carb, or you'll end up with massive vacuum leaks. - Matt
Since your car is a 1974, it is exempt from emissions testing. In California, gasoline powered cars built in 1975 or prior are exempt. I'm not an expert on 1 bbls but I believe that device on the right of the carb is the EGR valve (exhaust gas recirculation). It introduces exhaust gas back into the intake manifold. The clean nipple is for a vacuum line from the carb that controls the diaphragm within the EGR valve. I'm wondering if you can buy a block off plate and remove the EGR assembly. On the manifold photo the thick tube provides exhaust gas the the EGR. One of the skinny tubes provides hot air to the EGR valve (I think) to let it know if the motor warmed up, and I believe the 2nd skinny tube provides hot air to the choke spring mechanism to release the choke when the engine is warm. If you want to keep that, you can buy a kit for the headers that uses a clamped aluminum housing to allow hot air to rise to the carb. Someone tell me if I'm wrong about the EGR. Thanks. MD
Thank you both for the explanation. In that case, how can I plug all the points which have become exposed? And how many points that need to get plugged are there?
I'm going to back track a bit. The device on the right of the carb is the accelerator pump, not the EGR. It stays and that vacuum line should be hooked back up. Can you show us another photo showing where the large line from the exhaust manifold goes?
Does this car still have an air pump? If so that large line from the exhaust manifold is running back to the air pump.
The large pipe used to lead to this part of the manifold (pic 1) and connect to the back space of the carb area (pic 2). I'm not sure if this is the air pump? (Pic 3)
Ok. Shot number 676 is the EGR valve assembly. That silver part is the vacuum diaphragm that opens and closes the valve with vacuum. You can pull the rubber vacuum hose off the silver diaphragm and it plug it off nearer the carb. I like to use the plastic vacuum shut offs they sell at any auto parks store. You can try unscrew the pipe at the EGR assembly and screw in a metal bolt to close off the port to the EGR valve. Basically you are getting rid of the EGR system which I think everyone in this forum would agree with. Regarding the other two small lines, plug off whatever they were going to, but if you find your choke is not opening up on cold days, you might want to install a hot air line to one of the headers. Summit Racing sells the kit for less than 20 bucks. It looks like you don't have an air pump. Anyone of the 6 banger crowd already go through the procedures described? MD
Update: so I was able to put on the header/attach everything except plug the bigger pipe. I ran it to ensure everything was plugged in right and the only small issue now is that when it runs it sounds like it needs air or might shut down at times when pressing the gas, is this due to the unclogged point? Thanks
If the large pipe is unplugged it would now be the cause of a vacuum leak since it is attached to the intake manifold. Can you temporarily plug it with something such as aluminum tape? I also searched the web for an EGR blockoff kit where you could unbolt where the pipe plugs in and then bolt a blank plate across the EGR holes in the manifold. Haven't found one but maybe some of the Sixers know? You're making good progress. Is the header connected the the exhaust yet? If not, that might also make it run lean. MD
Yes! Thanks again for everyone's help! I lack an aerial view at the moment only because I currently have an embarrassing makeshift carb filter while I find one that clears the hood space ...
Thanks! I don't think they are anything fancy just some stainless steel I found on Ebay (http://www.ebay.com/itm/181504486766?_trksid=p2060353.m2749.l2649&ssPageName=STRK:MEBIDX:IT) for 200 with no needed mods to install. I feel my car run and sound alot smoother than original. The only downside right now is that I have no catalytic converter so the car wakes up the neighborhood haha
