Overheating ..... at a loss

[driberif19]

I have an 86 K10, with a 350 out of an 84 ish. My engine reseal turned into a complete tear down and rebuild with new main/rod bearings and RV cam.  I've finally got the thing back together and in the truck.  I have yet to finish my cam break in, due to many issues.  Freeze plug heater leaked on the first attempt, after about 1 minute.  Replaced that with a freeze plug and installed a heater hose heater instead.  My electric fan didn't kick on, so now I have it turning on with ignition instead of a thermo switch until I can get this break in done.  Now, fan going full bore, no leaks, and still over heats after about 2-3 minutes.  Upper radiator hose is cold, so replaced my new thermostat.  Tested this one in boiling water first.  Still overheating, with cold upper hose.
I pulled the motor initially due to multiple leaks, including one I couldn't figure out.  Figured I'd just do a complete reseal and call it good.  Engine ran fine before pulling it, just leaked oil.  Crank was turned, and main and rod bearings were replaced with .020, from .010.  Rings replaced and cylinders cleaned up (still had cross hatching).  Cam, cam bearings, lifters, and valve springs were replaced with and RV style, due to fuel pump lobe being nearly gone.  Block was cleaned at a machine shop when they did the cam bearings. Harmonic balancer, clutch, and PCV replaced.  Thermostat replaced just because, and then again after the overheating issues.  Water pump replaced because one the accessory mount holes was cracked, but wasn't leaking.  Oil pan, timing cover, and valve covers replaced for looks.  Timing chain and gears replaced with double roller.  Oil pump and distributor drive shaft are new.  So much for a reseal, right?
Truck is and 86 K10.  Engine is a 350 and 80-85 from casting number.  Heads are stock.  Intake is Edelbrock dual plane performer.  Carb is Edelbrock 600cfm.  Fan is a 2 speed Taurus fan.  The low speed turn on is the probe through the fins style, which mounts at upper hose.  Coolant doesn't get hot enough there to even turn the fan on, so I temporarily have the fan wired to turn on when key is on.
Anyway, what am I missing?  Upper hose is cold.  Upper driver side corner of radiator is warm, but can still leave your hand on it.  Everything else is hot, and coolant is boiling in overflow.  Any help would be much appreciated.

[bd]

Any chance a rag was inadvertently left inside of a radiator hose?  Was the thermostat installed upside-down?  Were the intake manifold gaskets open, restricted or closed at the forward coolant crossover passages?  Is the W/P belt tight?  Did you mistakenly install a reverse flow water pump?  And, my favorite, are you sure it's full of coolant - no air bubble trapped below the thermostat?

[driberif19]

I'd put money on it that there is nothing in the hoses.  They came off the truck, when in a corner, and weren't touched again till I put it together.  The first thermostat, I'm not 100% sure, but the one that is in there now is definitely in correct.  The belt is tight and pulley was turning.  I'm pretty sure I got all the air out.  Had the heater hose disconnected from the intake till that was full, reconnected it, and then squeezed the upper hose while filling till there was no bubbles at the radiator neck.  From memory, the intake gaskets did not have any block offs for the coolant passages, and looking at pictures I don't see any either.  The water pump # on the receipt is the correct number, but if it was boxed wrong, who knows.  It looks identical to the old one.
I guess, my guesses are the intake gaskets, which I'm not 100% sure on, or if the water pump is faulty or incorrect.  I think I'm going to see if I can see the impeller if I take the lower hose off and see if it turns when I turn the pulley.  If it does, I'll pull the intake off.  I just hope I find something definite, because this is already making me nervous as to how much damage I've cause my rebuild already.

[VileZambonie]

So you have a cooling fan running at start up and never purged the air from the system or had the thermostat open? I would suggest you remove the thermostat and fill the intake manifold. Reinstall the T-stat and continue filling the radiator. Run the truck with the fan off until the T-stat fully opens and install the radiator cap.

[Fourxbob]

Maybe put head gaskets on wrong? Easy done. And wouldnt that block water passages?

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[driberif19]

I swear I put the head gaskets on right, but then again, this is me I'm talking about.  So, I stuck an old dipstick in the port on the top of the water pump and verified the impeller was moving, turning the pulley by hand and hearing the impeller hitting the dipstick.  I'm not 100% sure about the intake gaskets still, but I can feel through a sensor port on the front of the intake into the head, so I know there is no blockage at the drivers front side at least.  Taking the thermostat out, the coolant was all the way to top, no way there was an air pocket there, unless it bled out between last night and now.  Radiator is full as well.  Since it looks like it's going to hail, I'm done for the night.  I did read somewhere about possibly having the distributor off by one tooth, being retarded?  I was going to check that as well, although while it is running, it seems to run fine.  Also, have timing at 8 degrees, but now that I think about it, that is while it is at 2000 RPM so I'm sure it's off.  Guess I'll get back to it tomorrow.

[rich weyand]

You're way retarded, since by 2000 rpm a lot of your mechanical advance will have come in.  You should be at 10-18* BTDC with no mechanical advance in.

Also, a thread on another forum went way deep into an initial overheating issue.  Here it is.
http://67-72chevytrucks.com/vboard/showthread.php?t=708861

[driberif19]

I know I have to fix the timing.  Wish I would have been thinking of that before, but that shouldn't be the cause of the coolant flow through the upper hose.  As far as the bypass from water pump to manifold, I might have to try it, but it worked perfectly fine before the rebuild.  Intake manifold is the same.  Someone at work suggested removing the T-stat and runnig it for a minute to see if there is movement in the radiator to rule out the water pump, since it is new. 

[driberif19]

Removed the t-stat, filled it up, started it....have movement in the radiator and upper hose got warm.  Since I know the t-stat worked, it had to have been an air pocket like most of you said.  Thank you for your help!  Going to finish up the break in tomorrow hopefully.  I might get to drive it before I blow it up after all.