Overheat problem... need ideas
 

well here we go again... did a little bit of work to the LB9 after a catastrophic failure of my 355. I threw together a modified LB9 cam, heads, mild tune. Now all it wants to do is overheat. But only when I get on it. It normally runs cool at 190 until you go above 3500. Its got a new t-stat, hoses, water pump, took out the heater core for the summer. The radiator isn't the stock GTA Aluminum, its the Steel stock one i had from another car. Would that cause it to not keep it cool?

idk, i had a similar overheating problem like that and it turned out to be bad cooling fans, are all the clamps on the hoses tight?

Air in the system? Do you have the air damn under the car?

And radiators are not steel. Aluminum or copper/brass

Sipping antifreeze?

checked all the hoses, i have a small leak at the top where one of the hoses goes in...
As for the air dam, Its got the stock GTA one under there, plus its got the Z/28 Nose openings so it has plenty of air going in there. and it just got overhauled so i dont see where it would be taking in antifreeze. I found today that my clear/green mixture of antifreeze has turned completely brown and thick. any clues on that?

brown usually means either you mixed the orange and green antifreeze together or rust. the coolant probably got low and something is rusting in there. just fill it, burb it and watch it. If you have any steel tubes at the heater hoses, they sometimes use them because it's cheaper than rubber, eyeball them good. Keep the coolant up and you should be good to go.

you said you threw it together, was the block fresh? Maybe the block is cloggd or full of sludge? Can you drain the block. pull the thermostat and flush the engine.

next suggestion would be to check the timing or if it's running lean?

If all that fails... What is your timing set it? Also could be running lean...

I really wish i knew what my timing was. I'm gonna try this weekend to flush the cooling system.. The timing cover that i got didn't have the Marker on it so i "eyed" up TDC with #1 on the cap and been working with it from there... but i can't even check it. What about having a MSD 6AL box with a Blaster 3 coil piggy backed off the oem wiring.