Hi all,

My 351M is going back together pretty fast, almost ready to go in the truck. The air pump won't make it back on (its locked up tight anyway), and I'm wondering about the EGR. Can I just bolt the spacer back on, with no other connections? Or should I leave the whole spacer off? How bad will the non-functional EGR affect my emissions? Alledgedly, the truck passed last time, but this time it will have headers and Flowmasters, among other no-no's.

Thanks!

 

If you just install the EGR spacer with no EGR valve, it will create a major exhaust leak under the hood. You need to either block off the EGR passage on the intake manifold (under the spacer), or install an EGR valve (operative or otherwise) to block off the exhaust passages on the back of the spacer.

Even if you don't need EGR to pass the e-test, I would recommend keeping the EGR spacer just for it's benefit as an inert carb spacer (increasing the intake plenum volume).
It depends on the emissions testing requirements in your locale.

There are three ways EGR can be an issue in e-testing:

Visual inspection - the technician looks for and verifies the presence of an EGR valve, and might look for apparent connections (i.e., vacuum hoses) for the EGR valve.

EGR function test - the technician applies vacuum (either directly to the EGR valve diaphragm or to a hose connected to the EGR valve diaphragm) to see if it stalls the engine.

NOx emissions - the gas analyzer used to test tailpipe emissions measures NOx, with a pass/fail criteria for NOx emissions.

Usually, the last two items are combined with a visual inspection, but not with each other. The EGR function test is an alternative to NOx emissions testing, if the test system is not set up for NOx testing. OTOH, NOx testing usually implies EGR functionality.

Check with your local e-testing authority to find out what the exact test requirements are for your specific vehicle.

 

In PA, the new law only requires visual inspection, so when I put my motor in last weekend, I hooked up the egr, and just plugged the vacuum line in front of the egr valve.

I also used a non AIR bracket for the alternator so you can't tell there was a pump there, so they don't ask questions.

 

Cool Galaxie.

You can run without the EGR, but you'll want to make a modification to the distributor to limit the full amount of advance under part throttle. Otherwise you'll either knock, or you'll be turning the timing so far back it will kill performance and economy. BTW, when you put a new timing chain on there did you advance it 4 degrees to reset it back to where it should be?

At one point, a poster on this forum described the emissions strategy used on the 351M and 400. Knowing all the changes they made helps to know what to do to improve the tune. Examples include the 4 degree retard on the cam, the extra vacuum advance for EGR, the rich tune of the carb to lower combustion temps.

Good luck.

 

I got an adjustable vacuum advance from my local napa for $26. The factory one is supposed to be adjustable, but mine wasn't, and it was broken. Once I did that and set it with a timing light, I got rid of the part throttle ping that I had since I did away with the egr. Now my part throttle torque is way up, and so is mpg I believe. It definitely runs better and doesn't knock like it used to.

 

Good going Willd!

 

Thanks. If it wasn't for this site, I wouldn't know half the things that I've learned in the last year or so about these trucks.