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1979 AMC 304 CJ-7 Emissions


Background:

The previous owner of my jeep did some fun stuff to the emissions on my CJ. When he put in the engine he put on a nice Edelbrock Torker manifold and a 4 barrel Holly Carb. The engine rocks, but it no longer has any of the emissions equipment required to pass inspection in the state of Missouri. In order to legally license my jeep I had to reconstruct the emissions systems that are missing. Here's a list of the parts that need to be there thanks to Merril Mosely and concurred by the Haynes manual (At least it's useful for once!)

2 barrel carb only
PCV (positive crankcase ventilation)= rubber hose and PCV valve
Fuel Evaporative Control System ( ECS) =charcoal cannister, and depending on
year/model, purge valve, manifold vacuum purge line, carburetor vacuum line,
liquid check valve, relief valve
Exhaust Gas Recirculation (EGR) = EGR valve, hoses, CTO (there's more stuff
on later models)
Air Injection (AI) =air pump, diverter valve, check valve, air injection
manifold
Spark Control= this includes Transmission Controlled Spark (TCS)
(1973-1978), Coolant Temperature Overide (CTO), vacuum advance control delay
valve, non-linear vacuum regulator system (NLVR) (1979)
Thermo-controlled Air Cleaner (TAC)= heat shroud on exhaust manifold,
connecting hose, air valve(thermostat or vacuum operation)
Catalytic convertor= conventional oxidizing catalyst (COC) or three way
catalyst (TWC)
good luck finding all this junk. Merrill


This is a large list and will be a serious pain to build from scratch. The first thing I did was call around and find a decent junkyard. I ended up at a local U-pull but all they had were 2 Grand Wagoneers. Fortunately the AMC small blocks all share parts, so the wagons make great donors. These were 1984s that were loaded. One already lost the top of it's engine but the other was intact. Someone had pulled the power steering pump and scattered some bits around. Fortunately I found the air intake a few feet over in the dirt. The carb was gone, but I spied a motorcraft laying in the back. Sweet. My lovely girlfriend actually pulled the intake while I scrounged on the other wagoneer for cruise control. We got all the bits and left the stock exhaust. I have headers, but a little bit of fabrication will solve the problems there. Missouri doesn't really care if you change the carbs and headers. Also since I have a 79 I don't need Catalytic Converters! I do plan on adding some high flow converters, but the $300 it's going to cost needs to wait a bit. I Dropped by Autozone and picked up a pair of check valve for $10 each and dropped by the hardware store.


The biggest problem had to do with my headers. I didn't have the air injection tubes. Since my headers were worthless to me without the tubes I decided to break out the tools and modify them a bit. I had the injection assembly that bolts to the wagoneer exhaust manifold. I cut off the ends that fit to the bolts and started planning. Then I broke out my drill and made some guesses on where to drill holes for the tubes to go into. Once I had all the holes in the right place, I trimmed the tubes to just go into the headers to keep the airflow that headers give you. Then I ground around the holes on the headers to clean the surface and I made some tack welds to get everything in place. Then I went to town with my mig welder and made some nice thick welds all around the tubes so there would be no leaks. Think of it as caulking with steel. After that I wire brushed them and sprayed them down with high temp paint. While I had the headers off I also wrapped them with thermotec exhaust wrap.



Next I reinstalled the headers and started work on the intake. My intake was missing the EGR valve. I wanted to order an edelbrock performer with EGR for the 304, but everyone in the world said they wouldn't have them for 2 weeks or so. So I ended up ordering an Offenhauser intake. It showed up and DIDN'T HAVE EGR!!! I get into the docs and find that I need a kit to add the egr to the intake. The kit includes some tubing, an EGR valve mount plate, some hardware and a carb spacer that has ports in it to inject the exhaust into the intake. The Offy intake doesn't require the spacer, the injection holes are already built in. This made me fairly mad, since I could have used my original intake with the kit! However, the Edelbrock torker intake was a bit extreme for the 304 so I went ahead and installed the new Offy. I chose to make my own exhaust crossover cover plate and weld a fitting to it for the EGR. Offenhauser tells you to drill and tap the intake, but my plate worked just as well. The Aluminum tubing wasn't in very good shape and I changed the way I wanted it routed so I replaced it with some copper tubing from the hardware store.



The next problem is where to install the CTO valve that activates the EGR based on coolant temperature. I bought a new CTO valve from the dealer. With the Offy intake, there is no clearance for the CTO at the thermostat. I chose to install my CTO at the Heater return system. I had an intake tube with the proper fitting from the Wagoneer intake so it worked beautifully.



Finally I replaced all the vaccum hoses that were in bad shape with some bulk hose from the suto store and ran vaccum to the various systems. I had a complete diagram on my white board, but it's since been erased. You probably need to construct your own drawing anyway. The Hanes manual from the Wagoneer and the Jeep are both very useful for working out the details. I didn't bother with the NLVR because the Holly carb I have has a vaccum port dedicated for the Distributor.