When I had my carb off yesterday cleaning it, I noticed that the EGR routing doesn't seem to tie into the exhaust at all. All it had was a plate that went under the carb that the EGR valve attaches to. The only thing I can figure is that exhaust is routed back through the intake, is gathered in this plate, and admitted into the airstream by the valve.

The problem is that it looks like the "chamber" in the plate that exhaust gases would gather is EXTREMELY corroded, probably from 35 years of caustic exhaust fumes. In fact it has eaten through the top of the plate and a small part directly into the air stream. This makes me think that I've probably got EGR all the time whether I want it or not.

Can anybody confirm my thoughts on how the EGR works?

Eventually I intend to do away with the 2bbl anyway, but I think this might be causing some driveability issues if it is running un-metered EGR all the time. The carb studs are too long to run the carb without this plate, and I don't know that the air cleaner would clear the coil and valvecovers if I did. There also looked like a little spacer on top of the EGR plate, under the carb. I'm thinking I could clean up the engine compartment and get a little bit better performance if I just removed the EGR plate and the spacer, and replaced them both with a single spacer of the appropriate height.

I know lots of 4bbl spacers are out there of nearly any height you would want. Is this 2bbl a standard mounting patern? Anybody done this?

 

Does a 1974 engine have an EGR valve? I thought the smog got started in 1978.
What you might be looking at is the system used to warm up the carb for better gas vaporization during cold starts.

I'd stick with the 2bbl, better gas miliage. If you want a high performance truck, buy one.

Did you rebuild the carb or just spray the outside with cleaner? Rebuilding would be better and allow for adjustments, it would be alot easier starting.

 

It's most certainly an EGR valve, you can't easily mistake them. It didn't have catalytic converters in 74 but it did have a whole bunch of other garbage that did very little to help the environment and robbed the engine of lots of power.

I believe a common misconception is that a 4bbl can't get good gas mileage. It can, provided you keep your foot out of it. Now if you gain a lot more horsepower, sometimes it's harder to keep your foot out of it. I will be sticking with the 2bbl until I can afford to do other modifications. The bottom ends seems pretty solid so I'd like to supercharge it, which will then have a 4bbl. At that point I'm really not interested in gas mileage. As far as just buying a high performance truck, I guess I could, but what would be the fun in that. What I have right now is the perfect project truck that has sentimental value and nearly unlimited potential.

I took it apart and cleaned it all out and rebuilt it. It starts great, runs great, I'm still messing with the idle to get it right.

 

In fiddling with the idle I ended up pulling the carb and examining the EGR plate closer. It is trashed and could not work the EGR at all. It's also completely plugged up so that it could not be causing a leak. I'll post some pictures later, it's pretty nasty.

If I can come across a spacer, I'll just replace it someday, but it's not critical.

 

I took my egr valve off and made a plate to block it off.

 

Don't know if this thread is still being read because it's old, but you can get a new plate from Edelbrock. You can get 2 or 4 bbl.
I'm doing up my 74 302 and I have the parts for egr but I'm not sure of the vacuum hose routing. Anyone got a diagram?

 

Why would you even consider running that on a 74 motor ?

 

I'm running this on a '74 because our provincial government is sending cops with government environment people to car shows and pulling in everyone that's showing their vehicle as they are leaving. They look for the engine block casting number to figure out what year the block is and then look in their books to see what emissions equipment it's supposed to have. Then they compare the engine to the books and start writing out fines for each item missing. If enough are missing, they pull the plates and it's off the road.
They are ruining our hot rod culture.
So that's why I'm doing it, I don't want to be taken off the road or fined.