I bought a new 383zz crate 8 months ago, runs great but overheats.
Called gilbert chevy today and now they are a chyrsler dealership.
Needed to ask questions about my problem and the guy said your
SOL, try talking to another GM dealer. Anyway I am running a 4 core
radiator, 6 blade fan, gm serpentine accessory drive with reverse
water pump,fan blade sits 1/2 way in the shroud. I am not running
heater hoses, but ran a hose from water pump to rear of air gap
manifold which helped a little (pass side). I am running a 180 thermostat
with a hole drilled in it. Car is running at 210 to 220 degrees. Should
I run another water line from front to back on drivers side? I don't
really understand the water flow in the newer 1 piece blocks. Any
advice would be great, Thanks

Running a vac advance distributor? More timing at idle can help it run better/cooler. Or look at big single or dual electric fan setup as a puller and ditch the mechanical fan. Why the reverse water pump? Oh and the obvious one is if its a clutch fan, make sure its operating correctly.

whats your timing set at??

Are you running a reverse direction fan?
I am pretty sure you are. But just to be sure.

Jerry

where is the temp probe at? does the gauge show 180 when cruising down the road and only go to 210 or so when stopped/driving slow? reason i ask is because if the probe is in the head it could read a little hotter than what the thermostat is. the big teller to me is if the temp fluctuates with driving conditions, or if it reads a constant 210. if it reads constant, that tells me the cooling system is adequate and the thermostat is working, you're just reading the temp at a hotter part of the cooling system, or your gauge is biased to read hot.

Bill,
The water flow is no different than any other small block. An extra water line probably will not help anything either, it sounds like your radiator/fan combination is not getting rid of the heat fast enough. Like someone else mentioned, do you have the proper fan for the water pump direction you are running ? Also, just because it is a serpentine belt setup does not mean it uses a reverse rotation water pump and fan, depends on the belt routing.

By the way, dont waste your time calling a GM dealer, this is not a problem with the engine, it is a problem with your cooling system. How does it run going down the road at 55 mph ? If it cools down then it is an airflow problem. Try "shooting" the radiator with an infrared thermometer, there should be about a 15 degree difference from the inlet side to the outlet.

I read all your suggestions and tried this, don't think this is right. I
let the car idle with radiator cap off, temp guage went to 210 deg.
There was no flow going thru radiator, stuck my finger in water and
temp was a just warm. Top hose hot as hell and bottom one warm.
Maybe just a little water flowing thru bottom hose from holes drilled
in the thermostat. Bad stat?, I have the gm reverse waterpump for
serpentine setup. Stat is new, any ideas?

pull the timing ahead a few degrees and hook the vacuum advance to manifold vacuum.

I also had a overheating problem with a new gm crate motor, at idle saw a good water flow though the rad, rad felt warm but the hoses were hot as hell turned out to be a bad water pump ihink the propella inside the water pump was slipping

John, I have no waterflow, checked all part numbers to gm sepintine setup, came as
a kit. Will check stat as soon as it cools down, maybe not opening at all? Thanks

Sounds like the thermostat is stuck closed or something is clogged, try putting thermostat in water and boil see if it opens, maybe the radiator is stopped up?
also make sure you have the correct rotation water pump for the serpentine system

Thank's everyone, problem solved. The thermostat was brand new but defective,
just put new one in and I have flow and 180 degrees. Still warm here tonight in Phx
and car won't go above that. Just hope I didn't hurt new motor. After 2 1/2 years
restoring I wanna drive this thing. My wife is about to leave me again if I don,t
start fixing the house stuff!!!

Now you can go have fun and start worrying about how to get melted rubber off your quarters, right : ).

You read my mine,actually wanna give my friends 502 camaro a little grudge run.
He's one of my customers, wanna see if I can piss him off a little...