How does a j code 6.2 differ from a c code internally? I guess a j code does not have an egr also. Will a j code engine get better fuel economy in the same application? Do j codes last longer? Can they handle turbocharging better?

I'm Also wondering what years the j series was made.

j codes were made all model years. the J code stuff was found in 3/4 ton and up. Differences were the injector pump calibration and the opening in the pre chambers, along with the egr junk that was on all c code engines. That's it.........same engine, calibrated with a little more fuel from the factory.

I bought a 1984 C engine out of a burned new 1984 Chev G20 van (the Trailswagon van had been purchased, but the brakes and tires showed no usage.


I first installed the engine in my 1970 C20 due to a blown 350 engine. I removed the butterfly in the exhaust manifold, put solid (no holes for the EGR)intake manifold gaskets on the engine, removed the EGR, and welded a plate on top of the EGR plate (after cutting the EGR off). I put the J engine heavy duty injection pump on the engine when the original C injector failed so then I had a J engine configuration. The heavy duty does pump more fuel, but then I did gain more power. A few years back I had a muffler shop install a balance pipe between my dual exhaust pipes. The balance pipe gave me another boost in power to the extent that I didn't have to downshift to second gear (manual trans.) anymore in going up steep passes. My engine still puts out maximum power with minimal smoke on a dynamotor (May 2004 county emission test). The engine has been getting warmer each year so maybe my head gaskets are beginning to plug.