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Might seem silly, but is the fan installed on the clutch such that it’s rotating in the correct direction?
The reason I bring this up is you mentioned air pushing out of the fan shroud gaps which implies the mechanical fan is trying to push air into the radiator, vice pulling air through it.

Another thought might be a bad / plugged / fowled radiator or just an undersized radiator. Was the truck a gasser before the conversion and did you reuse the stock gasser radiator?

Posted edit: I re-read the original post , says "new 7.3 radiator", so that takes fowled radiator off the possibilities list.
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Are you sure you have all the air bled out of the cooling system? Sometimes you have to jack the front of the truck up to get it all out.
Assuming the degas bottle is the highest point in the system and the thermostat opened, I can't imagine an air pocket would stay in the engine.

OP, are you running a 7.3 degas bottle in the stock location and if so, how is it connected to the cooling system?
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I will leave the A/C off on the way home today and see if it behaves any different in traffic.
That's sounds just miserable. I'm not far from you (I'm just north of San Antonio), and I won't drive without AC.

If the AC broke in ever vehicle in my little fleet, I'd rent a car before driving without AC.
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In my Fummins swap truck I used a giant fan off some industrial Cummins I think (part number visible in pics on page 8 of the below linked thread) the stock 12 valve fan is actually kinda small. I have no overheating issues driving around in San Antonio with the AC on in traffic, temps never get above low the 190's.

The only issue I have (more of an annoyance really), is before the engine heats up and the fan clutch kicks in, there isn't enough airflow across the AC condenser to make it work well. So when you first get in the truck and its hot as all heck inside, the AC kinda sucks until either you start driving or the engine get up to temp enough for the fan to actually start pulling air. But once the engine is up to temp , and the fan clutch is working, the AC works fine even at stoplights/ in traffic. I've though about adding some auxiliary electric fans for the AC condenser, so the AC would work good even with the engine cold, but I haven't bothered yet.

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The fan I have is new and the part number shows it fits 91(intercooled)-2002. It is a 22" 7 blade.

Antonm, It looks like you are still in the process of your swap and your other trucks are sticks? I was curious if you had any input on EGTs at idle in drive as they seem really high to me 550-660? from what I can find on the forums it seems like 450 or so should be normal. LOL I actually don't mind the heat, only trying to get the A/C nice and cold so the girlfriend will be able to ride in/drive this truck.
The 2010 F250 Cummins conversion truck is pretty much done. Its a running and driving truck, only thing left to do really is make the cruise control work (and maybe some cosmetics, but those are still maybe's). Its an automatic (still has the factory 5r110 the truck came with), but I don't recall off the top of my head the idle EGT's.

The 2005 Excursion Cummins conversion really hasn't gotten started good yet. I just got the engine back from the machine shop and I'm in the process of putting it together.

The 97 Dodge is a manual trans truck (the only thing I know about 2nd gen dodge automatics is that I don't want one), but that truck's AC works just fine here in San Antonio too.

The next time I drive the 2010 I'll check the idle EGT's to see what they are in drive with the AC on.

Post edit: Looking through the pictures I have saved on my computer, I found one of the 2010 idling with the AC on, but the trans was in park at the time. I'll make an effort to see what the difference is (if any) with the trans in drive. Although, I'm not sure it'll be apples-to-apples for us as all my Cummins engines are P-pumped. They may behave differently from the VE's , IDK, never played with a VE.

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Isn't the VE pop pressure lower than the P7100?

If it is, and injectors set at P7100 pop pressure are installed, that should retard the injection events, not advance them.

Which could explain the black smoke at idle I suppose, if the injection events were happening a lot later than they're suppose to. Could that cause high idle EGT as well?
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Antonm, It looks like you are still in the process of your swap and your other trucks are sticks? I was curious if you had any input on EGTs at idle in drive as they seem really high to me 550-660? from what I can find on the forums it seems like 450 or so should be normal.
Looks like 450 is about right for EGT at idle while in drive (at least on a P-pump engine, I assume the VE would be similar). The below pic was taken after about a 45 minute drive with the ambient temp in the low 80's (early morning temps here in TX). Truck was idling in drive with the AC on.

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