Hoping someone can help - recently inherited this 75 C3 with L48 engine and just working my way through what has been done to the car.
In attached picture I see that the hose from the EGR goes to a TVS switch but the hose form that is not connected to anything (resting on top of AIR pump) there is no hose coming from the EFE. does this indicate that the EGR is not doing anything? In which case can it be disconnected? the hose from the distributor is connected to the carb but there is another hose near the carb which appears to have been cut and I see one of the ports on the carb is not capped - should it be?
Should also mention that exhaust has been modified to straight through exhausts and catalytic converter has been removed. If I can get rid of the air pump and tidy up the engine bay would like to do so.
Sorry for all the questions but a newbie to the forum.

 

They’re a bit hard to find nowadays, but they make EGR delete plates. Otherwise you can make one yourself using the valve as a template. Any open ports on the carb should be capped if they’re not being used.



Another option is changing out the entire intake manifold. I recently bought another 1976, and I bought an Edelbrock 2101 intake for it. It’s aluminum, fits under the stock hood, and is smooth where the EGR valve would be.



Some other things to note, your carburetor has been converted from the ‘75 only dual choke pulloffs to a singular one. It’s been converted to an electric choke, and it looks like your vacuum advance coming off the distributor is hooked up to its factory ported vacuum source. The car will run better if this is hooked up to a full manifold vacuum source.

It’s hard to tell from the resolution of the photos. Are the screws on the airhorn of the carb torx bits? If they are that would mean the carb is a service replacement piece from the 80’s.

 

Back in the 70's, first thing we would do to any Chevy, remove the stupid airpump and delete the EGR.
I'm not sure if it helped performance or not. But we all did it.
I had a air pump seize up on me once on a old Impala that was a winter beater car. That made for a exciting day.
Truth is the air pump didn't reduce pollution, it just pumped air into the exhaust to dilute it.

 

Cool original car..
take some more detailed pics.
i would save the parts , but get rid of it all, properly cap off lines as needed.
agree with making your own cap for egr, but make sure sealed/ blocked.
below is a thread and diagram posted. Not sure if you have exhaust restrictor EFE flapper, but. Would remove that too and replace with spacer
not sure how it runs, but one of the best decisions i made was to have my carburetor rebuilt and calibrated by Lars. Google it 😆..
good luck!
https://www.corvetteforum.com/forums...m-diagram.html

and get a 75 manual !

 

Thanks for the responses - thought I had also created some major issue as the car would no longer start yesterday. Have attached some more pics.
The carb is a Rochester but does have the torx screws so must have had some mods done.
I am going to remove the smog pump, egr as looks like they are no longer being used anyway.
Now as far as the car not starting that was an interesting problem. Yesterday backed the car out of the garage, running ok let it run for a short time but after putting it back and before I could put it in park the car stalled. Tried to restart but no success, engine cranking over ok but would not start. I hadn't changed anything other than taking the air cleaner off. Tried again a couple of hours later and still no luck.
Tried this morning and same result, noticed that the choke was fully closed and no movement when trying to start. Got out multi meter and no voltage to the electric choke but next thing is I see some smoke coming from other side of engine so after the usual panic checked the source and found a thin wire (18 guage or less) resting against a valve cover and smoking. Traced it back to come from the same connector into the distributor for the tachometer, as soon as I moved the wire away tried to start and engine fired up straight away. You can see in the picture there is a filter that is not connected to anything but looks like this wire may have been connected to it in the past and was flapping around until it eventually shorted out - why would such a small gauge wire be used? Amazing how the engine could be immobilized by such a small thing.
Going forward will need help on setting up the carb as I have very limited experience in this area.

Thanks for the support


Wire from tach

showing torx screws

 

Welcome to the Corvette Forum amphillips123! This is THE "Place to be" if you have issues or questions regarding your Corvette.

The vast amount of Corvette experience here can and will help you IF you give them the most detailed background information in regard to your issue as this helps everyone. There is a Profile page where we describe our Corvettes so others can see what I am working on. The more information the better for lots of the Forum members who can troubleshoot your car "with" you.

For starters you will need a good copy of the Factory Service Manual (FSM) for your particular year and then a good multi-meter and you should be ready. I have a couple different schematics and the various vacuum hose maps and charts in my shop. If it is available find a copy of the 1975 Assembly Instruction Manual (AIM) as that has the various assemblies being assembled and is one of the very valuable resources we still have from the factory days. Rockauto has some of the manuals and other resources available on DVD which keeps the costs down.

 

Glad you were able to get it started.

The Quadrajet is definitely from the 80’s, the carb number is 17085004. That number comes back for a 1985 pickup truck with a 454. I’m guessing the jetting settings might be a bit different than what you would want on your 350.

The correct carb number for a 1975 L48 with a manual transmission is 7045223

 

I also use the Parts and Accessories Catalog as a go to manual.
It has good detail illustrations and all the oem part numbers.