I am having problems with my cooling system in my LT1 in my 85 Z28.

When I took the car out for a short loop around the town my coolant reservoir fills up as expected, but the coolant seems to boil up from the overflow line coming from the top of the rad. The coolant reservoir then fills to the top and then overflows. This alwasy seems to happen at 140 farenheit (assuming my gauge is accurate, which sounds right because the fans aren't even on yet and they turn on a 160 F)

I always have the car off before it actually starts overflowing. The weird thing is after about 2-3 minutes the level in the coolant reservoir drops pretty rapidly and pretty much emptys itself back into the engine.

Anyone know why this is happening, I believe I have everything hooked up properly and I am using a 50/50 mix of antifreeze and water.

The best idea I can come up with is there is an air pocket somewhere in my coolant system.

You might try taking the rad cap off cold, and then starting the car. It won't build pressure this way, so it shouldn't make a mess. A lot of times this burps the system. Also turn on the heater in the car to make sure that coolant is flowing through the heater core too.

correct me if im wrong but isnt that too much anti freeze??? plus try using red line water wetter if u think u r overheating. it works great

That's a good mix but I found out the problem.

The rad cap was not working properly, it's all fixed now.

It was opening before it was supposed too.