Hello everyone.....

Here's my prob.....I have an 81 Z28 with a mild 402 BB. turbo 400 and 12 bolt 4:10 gears. 250mls on the fresh rebuild...Car runs HOT! Here is the list of new stuff.....
~New Summit aluminun rad. with two 1inch cores in it.
~New Edelbrock high flow water pump.
~New high Flow 160' Thermostat.
~New Derale brand 16" 2,195cfm Electric fan.
~New upper and lower hoses.

On an 80-90 degree day the car runs HOT! Thermo opens at 160 and then i hit the fan switch and then it slowly creeps 180-185-190-195. This is at cruising speed 50.mph at 2,700rpms. in order to keep it from going over 195 i have to put the heater on FULL BLAST! and i am roasting in the car. going down hill under deceleration the temp. comes down 5-10 degrees...but go's back up when i am back on the gas. whats going on here? I shouldn't need "Water Wetter?" maybe an aluminum fan shroud? very,very, frustrating:mad: Thanks for any help you may have for me.
Jamie

Too much timing or carb too lean?

aaaaaaaaa..............................195 isn't HOT, anything above about 225 is hot, and even then i've seen that sitting in traffic in 90* weather

is there a spring in the lower hose?? all those high flow things are great...but the more time the water spends in the radiator the cooler it gets, so if your just blowin the water around the system like a race track its goin to run hotter than it should. put a reg 160* thermostat in it and see what happens

If that elec fan, the only fan on your engine?

If so then thats not enough to cool it IMO. You need around 3,000 cfm or more, the the fan needs to be shourded.

Just an open fan does very little for moving air through the rad. The shourd helps the air to flow one way, in 1 path. The fan and shourd needs to cover atleast 75% of the rad. core

Also elec fan's needs to be set up as a puller.. Fan mounted on engine side of rad. and wire to pull air through rad and blow toward the engine.

The like Kyle said.. If timing is wrong.. Advanced too much or retarded too far it will run hotter, if carb jetting is too lean it will run hotter.

What's the highest the temp goes to? 190-200* aint really too hot. At 210*, 215* thats when it's running a good bit hotter than it should and 220 and above is when you have a real prob with overheating.

Intitial timing 12 degrees.....and do's not crank slow like it's to far advanced. I never messed with the advance coming in. Brand new MSD H.E.I pro billet. for my application.

And 750 Demon (which i highly recommend) Factory tuned for same app.

is there a spring in the lower hose?? all those high flow things are great...but the more time the water spends in the radiator the cooler it gets, so if your just blowin the water around the system like a race track its goin to run hotter than it should. put a reg 160* thermostat in it and see what happens



I actually had a reg. 160 in there and had the thought of.......restricting the flow with a stock one.

If that elec fan, the only fan on your engine?

If so then thats not enough to cool it IMO. You need around 3,000 cfm or more, the the fan needs to be shourded.

Just an open fan does very little for moving air through the rad. The shourd helps the air to flow one way, in 1 path. The fan and shourd needs to cover atleast 75% of the rad. core

Also elec fan's needs to be set up as a puller.. Fan mounted on engine side of rad. and wire to pull air through rad and blow toward the engine.

The like Kyle said.. If timing is wrong.. Advanced too much or retarded too far it will run hotter, if carb jetting is too lean it will run hotter.

What's the highest the temp goes to? 190-200* aint really too hot. At 210*, 215* thats when it's running a good bit hotter than it should and 220 and above is when you have a real prob with overheating.


Yeah...there is one fan....

And it's a puller.......i thought about a shroud....but that would meen the fan would have to run all the time...because the out side air coming in would be restricted if the fan was off...(Make sense?) and i would be relying souly on the fan to cool...if it burns out.....i better start praying:eek:

It's ran 210* once already and came out the cap, into the over flow. And the heater on is the worst! I have not been driving the car long...260mls. and i ain't gonna have heat on in the summer time just to drive it.......there is an answer some where.....

When you are going 50 mph the fan isn't helping you at all. As a matter of fact, it may possibly be fighting you.
Fans are really only good at low speeds, IIRC under 30 mph. After that the airspeed from the car moving is faster.

Any other thoughts would be greatly appreciated and welcomed!

When you are going 50 mph the fan isn't helping you at all. As a matter of fact, it may possibly be fighting you.
Fans are really only good at low speeds, IIRC under 30 mph. After that the airspeed from the car moving is faster.

Out of town and in fresh air it's kinda stable at 185-195....still seems high thought on an ave of 195....But i will try your theory...thanks you!

195 is not hot.

Like the others have said, 225+ then we're talking hot. Even GM states optimal operating temperature is around 190-195.

Shroud...all the way. Build a good sealed shroud and your problem will be solved. You can't run a cooling system in street car w/o one.

i had an overheating problem like you had. i had the griffin rad, summit high flow pump, 160 thermo, all new hoses, flushed and clean system. i wired my fan to run all the time, and it barely gets to 160 now. i dont have a shroud and i have a pretty hot 355. i live in texas, so it definately gets tested during the summers.

yeah 195* is the temp you want.. Proven time and time again 190-195* makes the most power, less wear, etc..

If you run the engine too cool (160's) you will get a sludge buid up over time, more carbon build up, less power, etc.


Your fan is the #1 prob I see.. It's not moving enough air at low speeds to keep the temps steady.. Like I said you need over 3,000 cfm of air flow from the fan..

And the FAN HAS TO HAVE A SHOURD OVER THE RAD.

Get rid of the electric fan and put on a shroud and a good flex fan.

Get rid of the electric fan and put on a shroud and a good flex fan.

A+ ^ , those nylon stlyes are cheap and very light. put one on my car with a 180 stat car runs 185-193 even in the hotest days. BTW 195 is not hot...many people have the misconseption of a normal running engine. when they see 200 they panic. just my .02

I have a 427 w/ a cheapy summit circle track rad, stock water pump, and 160 thermostat. I am running elec fans off a 03 impala and I wired it using a mid 90s caravan, on at 180 off a 170. I have a toggle wired in to by pass the switch. On the only long distance trip I have taken (about 30 miles), it came on a few times going down the road but never ran over 180. I drive it to and from work and never have a problem. I can switch it to on all the time and it will run below the thermostat temp (120-140). I have let it idle in our dealership for an hour messing with the carb and such never above 180. I know what GM and everyone else says about temp but I think differently. I think the more on the edge your engine is the more important coolant temp is. Sure my 3.1 monte gets great mpg at 195-220 degrees but if you are on the edge of detonation you need to say in that cooler 160-180 range to help prevent intake heating. My engine will never be together long enough to worry about sludging and such. I run it hard enough to keep out the carbon. Plus I change my oil about 10 times more often than normal because of fuel contamination from cold starts at the track.