73 - L48, California car...... Can anyone post a pic of where the Vacuum source comes from, (on the carb) for the EGR valve??

Is this valve suppose to be open during idle? I have removed almost all of the smog equipment, but I would like to retain the EGR valve.
The number on the carb. is; 17054919
1350
Thanks for any help.

Steve

 

http://shop.docrebuild.com/1973Corve...onHoseKit.aspx

This is how the hoses are routed for an Auto. Hope this helps. Do you have an Auto or 4 spd?

 

The vacuum sorce for EGR valves is always ported vacuum, so that would be the port on the passenger side of the Q-jet that goes to the vacuum advance on the distributor.

This was one of the first attempts at EGR and they were problematic. The valve is normally closed and is supposed to open slowly as you accelerate, adding inert (spent exhaust) gas to the intake charge. The idea is to reduce cylinder temps and dilute the intake charge to reduce emissions. The problem is that they opened too quickly and cause a pretty bad stumble on acceleration. Later GM versions used a delay valve in the vacumm line, stiffer springs in the valve itself, a restricted orifice in the valve, or a combination of all three.

In a low compression engine like yours, you can leave it disconnected and it will work well. If you have pinging issues, you can always hook it back up and limit the vacumm in some way. If you want to test it, apply vacuum at idle and it should kill the engine. hope this helps.

Edit: I had forgotten that GM hooked the distributor to direct vacuum on that year, so DO NOT hook the EGR to that port (the one on the front)!

Personally, I never liked the direct vacuum style advance hook-up, and I changed alot of customer cars over to ported advance with good results, both in mileage and power. It really depends on driving style, and it didn't work as well for people that had a light foot on the accelerator.

Hans

 

On this particular carb. there are two ports on the right front corner. a rather large one near the base and a smaller one near the top. I want to make sure that I have the hoses correct, before I attempt to set the timing.

 

Here are a couple of shots of my old 75 motor setup if it helps any.





As you can see it's tied to the goosneck where I believe it was supposed to allow the EGR to open when the motor got to operating temp. I don't think your EGR should be tied directly to vacuum, if it was it would be open all the time and would defeat the purpose of having it vacuum controlled. Maybe someone else will chime in with better info.

 

Thanks for posting the pics, but they don't even come close to my my setup.http://i606.photobucket.com/albums/t...ics/after4.jpg



This is what it looked like when I first got it.

 

Well that looks about the same except mine is routed thru that temp sensing switch first near the gooseneck................smog **** stuff! Then it goes into the port at the base of the carb, looks like yours is routed to the same place.
What's wrong with the way it's shown in your pic?

 

Your cab is not original but it appears that everything was hooked up properly. I hope you didn't toss out the smog stuff- it's worth a fair bit of money.