How to make EGR work

[johnson350]

It sounds like you did everything the right way. Well, I once did all that too, and the 231 still had crummy gas mileage. I think it's because you are asking a tiny motor to push a heavy car so your foot is always in it. A big motor doesn't even have to work hard, and my 301 gets better mileage than the 231 ever did. A 350 would just be incredible. Hey, you got time, just be patient.

Much much happier now.

I'd say I must have done something right, I just got everything all hooked back up with the new timing and took it for a test drive. Holy smokes, night and day difference! Still a v6, but I can squeal tires off the line now. Its waay quicker off the line than it ever was, and I have a feeling it's gonna get better mileage too.

Yeah I hear what you're saying about a bigger motor not having to work as hard. There was a Buick 455 for sale around here for 400 bucks awhile back, all complete, but I still would like some good mileage, so I figured a small block would be about the perfect size for a G body

 

[johnson350]

Couple things;

Are you sure your numbers are accurate, because if you have 20 degrees of vacuum advance ( which sounds about right for a stock one ) and you say your initial timing is at 17 WITH THE VACUUM ADVANCE, then that means your base timing is actually set at 3 degrees AFTER tdc which is way too low. Verify your base timing with vacuum advance UNPLUGGED.

Without EGR, you need to run less vacuum advance. You can do this by limiting the travel of the rod on the vacuum advance unit or you can get an aftermarket one that provides less advance.

Timing tape on your balancer is a cheap easy way to be able to check your total advance as well as knowing how much mechanical advance you're getting at various rpm's.

DUH I understand now! Wow I feel kinda dumb now haha.

Yes, its a 20 degrees can and I had the timing at 17 plugged in. That was exactly what my problem was, the timing was waaay too low. So thats why the car was such a slug and got really bad mileage lol!

I reset the timing at 17 degrees with the vacuum UNPLUGGED. Holy crap what a difference! So now the next step would be to get the tape for the balancer and find out the total. Just curious, why do you need to run less advance with EGR?

 

[DoubleV]

Make sure your YOTAL timing isn't too high. Should be around 34-36ish. You'll have to verify that.

You have to run less vacuum advance without the EGR because without the EGR diluting your mixture, your engine won't be able to tolerate all the additional part throttle timing advance. With the EGR, the extra timing from the vacuum advance makes up for the diluted mixture from the EGR.