7.4L EGR Information

[Crazydavez28]

Ok had time to mess with it. If you are messing with your EGR setup here are some facts.

Fittings in the manifolds are both the same 6400-14-12 7/8"JIC to 3/4"ORB
This translates to a 1 1/16"-12 thread size in the intake and exhaust manifolds.

EGR Tube is 7/8"ID and 20" Long Discontinued by GM


Alternatives might be a 1"x18" SS Supply hose and install 3/4" ORB to 1 1/4" MNPT Adapters in each manifold. You will need to ditch the rubber gaskets and use copper or SS washers for sealing.

If you simply wish to plug the ports purchase -14JIC Female Caps and install.

These fittings will be hard to find at anything other than a hydraulic shop. I recommend finding them online.

 

[Manmeyco]

Wow thanks for this info, was looking around for the right fittings, and thanks to this, managed to find plugs that fit perfectly.

One correction, is that it's -12 JIC, not -14.

For anyone else looking for a plug for the intake manifold and/or a cap for the egr hose, here are the links to the plug (model AF 7237-12) and cap (AF C5129-12) I bought, they worked perfectly and threaded all the way in (haven't pressure tested them though, but they look like they sealed well).

If you're looking for fittings and those links are down, the correct size fittings are sometimes called 3/4" ORB (O-ring boss), and sometimes 12 AN.
It might be easier, if you can't find plugs, to find adapters down to smaller sizes, that have caps more readily available.
One useful site is McMaster-Carr, they have pretty much every piece of hardware you'll ever need, with detailed specs, dimensions, and even CAD files.