My 86 Z28 keeps over heating on the highway.
In town the car runs fine, but once I get out
on the highway and I'm hot within ten miles.

Here's what I got it's a 305 4 bolt main with
an energizer cam 282°duration, stock heads
(I think the engine came out of a truck) with
Hooker headers that have a 3"inch dump the transmission is a turbo 35O ( the 3-speed may be adding to the temp rising because the engines running at higher rpm's) I have a single electric fan cooling a 3 core brass or cooper radiator. I had a 160° thermostat in the manifold but I pulled it out. This bought me a couple more miles on the highway, but the Z28 still got hot! I've heard that pulling the thermostat can cause hot pockets or hot spots on the engine? I know the headers are producing a lot of heat. So the only solution I can come up with is to put in a dual fan and maybe an aluminum radiator. As a side note: I read in one of my old super chevy magazines that putting in a higher degree thermostat can actually help cool your engine better, because it allows the antifreeze to stay in the engine longer to absorb most of the heat from the engine than recirulate to cool in the rad. I could have been smoking something when I read that. does anyone have suggests on what I should do?

 

Sounds like you are missing your lower air dam. It's a piece of black plastic that runs along the bottom of the core support directly below the radiator, the thing that always scrapes (used to scrape?) on parking curbs and stuff like that. These cars do not get enough air flow through the radiator to stay cool at highway speeds without it.

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"So many Mustangs, so little time..."
ICON Motorsports

 

I have a air dam, but it's shorter then the
air dam on my brother's Iroc! Maybe thats the
problem! It looks like its been cut, the moron
that had the car before me probably cut it.