C-code vs J-Code differences?

[neo]

Hi all. I searched and did not find specifically what I am trying to determine, and apologize ahead of time if I just missed the mark. Here is the question:
What are the fundamental differences between the C and J engines, other than EGR/intake? I have the 6.2 tech manual/book and have read it many times over and understand the egr intake vs non egr. I also realize there are differences in the I/P's. Where this is coming from is I recently found an 83 or 84 (still need to see the title to get exact year) van witht he 6.2 the dude wants rid of. He is willing to nearly give it away. He claims the engine was running when it was parked several years back. It has the 700R4 tranny and is 2wd. I noticed it had an aftermarket filter/water sep with a cabin mounted alarm. The engine is pretty grungy, but apears to be all there. My real question is what differences are in the block itself? I LOVE my 89 burb and originally got it to transfer the engine to a wagoneer, but the burb is so useful and dependable I can't bring myself to killing it. So, I am wanting another engine for the waggy. This looks good, and I would DEFINETLEY find a j-code intake and deal with the glow controller issues etc. I would also rebuild it from the block up, blueprinting as I go, girdle, etc. No turbo plans. Just want a good block to start with. Not certain what block differences there were between the two versions. Any input is greatly appreciated.
R/S Neo

[john8662]

C v. J

TDP Court of Law

Besides the external differences (intake manifold) there are other changes to have a "True J".

The other difference include precombustion chambers in the heads and injection pump calibration.

So, if you're starting from the ground up with this block out of the van. Then you'll be able to address the issues with the other components.

The heads can be retrofitted with J precups, which can be obtained via some of the vendors.

The injection pump can be recalibrated for J specifications.

IIRC, the J pump varies from the C pump in that is is calibrated to deliver 1CC more fuel and ~1 degree timing advance with the advance piston.

J

[neo]

THanks for the info John. I am primarilly interested in the block and would j-code the ancillarary compnents. To take this one more step, how about the differences in the 6.2 block compared to the 6.5 block? Were there significant differences between the two? Did they strengthen the bottom end for the 6.5? The conversion I am planning on doing is what I would consider fairly extensive (I may be a wimp!) and would strongly desire to set it up once, or at least stack as many of the chips in favor of longevity. Thanks for the info.