I have a 408 sbc and a radiator kit from jegs with the single electric fan. The cheesy thermostat that came with it seems to come on too late or comes on too soon and stay on. I have gotten over 200 degrees and its making me nervous. I want to know how hot is too hot and what about just putting the fan on a toggle and just turn it on all the time while driving.

I know there are better thermostats on the market but for know i dont want to buy one.

BTW i also have aluminum brodix heads if that makes a difference.

I personally don't like more than 210 but even 220 shouldn't hurt your engine. What's wrong with your stat? put it in a pan of water along with a cooking thermometer and put it on the stove. Pay attention to when it starts to open and when it completely open to see if it's working properly. From there if it's rated at 180 and your system can't cool the fluid below 180 it's not the stat's fault it doesn't close.

When does it over-heat? Sitting idling or when driving down the road?

Dennis I think he is talking about the electric t-stat to control the fan.

If you want to use a toggle switch, make sure you use a real to turn the fan off and on, if not you will burn the switch up and if you are unlucjy you will burn you car up with the switch. Personally I don't like have to rely on my memory to turn the fan on, I have had cars wired that way and trust me you "WILL" forget to turn it on.

Fan control units or temp switches aren't expensive and you don't need anything fancy but, I would advise very strongly that you hook up a temperature switch of some sort. I usually run both a switch and a temp. switch just in case the temp. switch fails.

As far as what's too hot, I would think about 230* would be about the limit before damage is done (no fact to back that up just my opinion) I don't like to see anything over 210*.

which fan, and when does it get hot?

Jody

Use a fan switch kit from Painless or the Dakota Digital electronic fan controller. If you are running a 180* thermostat(which you should be), then here is the Painless kit:
http://store.summitracing.com/partdetail.asp?autofilter=1&part=PRF%2D30102&N=700+115&autoview=sku

and here is the Dakota Digital fan controller:
http://store.summitracing.com/partdetail.asp?autofilter=1&part=DAK%2DPAC%2D2000&N=700+115&autoview=sku

The Dakota is fully programmable. The Painless switch goes in either the head or the manifold. I currently run the Painless switch, but I have a Dakota controller, but I am just too lazy to hook it up. Too many wires for to fool with right now.

I have the Dakota and like it. Its easy to program I like the part of the program when you turn the engine off the fans can be set to run 15 seconds to one minute which is pretty cool on a 69 Camaro.

This is what I did, maybe overkill or not the most popular fix here on the board but I generally don't like to do thing the easy way...

I did a 16" 2600 cfm pusher fan mounted to the front of the radiator connected to a thermostat switch and a toggle mounted inside the car so I can shut it off when I want. (I really only need it in traffic at red lights) I used a "painless wiring kit".

I also did an 18" flex fan with shroud. And at the advice of this board I installed a 180 thermostat.

Of course an aluminum dual puller fan setup would have done the trick too, but I just don't like to depend on electric fans completely. And I like the look of a mechanical fan under the hood.

Here's some pics - http://1969z28.com/cooling.html

Good luck, and of I course thank everyone on the board for their advice

Dennis I think he is talking about the electric t-stat to control the fan.


Thanks Royce, re-reading the post I can see that now...

CSR makes a nice little controll unit only 4 wires if I remember right. I have one to go in my car. Comes with a relay and sending unit. it's digital and can be programmed to come on at the temperature you decide. It's also a gauge and you can operate/adjust it from the drivers seat. http://store.summitracing.com/partdetail.asp?autofilter=1&part=CSI%2D1225&N=700+115&autoview=sku

One other point about running the fan via a toggle switch, at highway speeds chances are the fan will be a restriction and need to be turned off. As you can see the fan controllers are handy and do a lot of "thinking" and work for you. Imagine driving down the freeway turn the fan off, hit the exit and forget to turn it back on, not good.

Where is the sender unit for temp gauge located?,if its in the front of the inlet manifold the temp gauge can display higher operating temperature as this is the water returning to the radiator with all the heat energy its picked up from block.
I take it the block is 40 thou oversize in the bore,this is getting towards the area where temperature can be an issue on factory 400 blocks.
Generally if the temperature comes down quickly once on the move its a radiator/fan issue.
Sounds like a very stout engine Just a few points to consider.

TT,if I ever get hotter than 220 I would pull over let it cool a while JMO, even though 220 is 10 deg hotter than my 05 Tahoe runs normal...I use to run my E fan on a temp relay, in the top rad hose ,I could dial in when to come on and to turn off ,but just got it through a fused switch ,I have a 5 blade fan and shroud ,and only turn my E fan on when in traffic and it goes up past 200 .... Happy Motoring Bottom line 220 deg Max temp ,Call me if ya want, I have Pts. for you

This is what I did, maybe overkill or not the most popular fix here on the board but I generally don't like to do thing the easy way...

I did a 16" 2600 cfm pusher fan mounted to the front of the radiator connected to a thermostat switch and a toggle mounted inside the car so I can shut it off when I want. (I really only need it in traffic at red lights) I used a "painless wiring kit".

I also did an 18" flex fan with shroud. And at the advice of this board I installed a 180 thermostat.

Of course an aluminum dual puller fan setup would have done the trick too, but I just don't like to depend on electric fans completely. And I like the look of a mechanical fan under the hood.

Here's some pics - http://1969z28.com/cooling.html

Good luck, and of I course thank everyone on the board for their advice
Drew, on one of your first photo's the fan belt to alternator alignment looks to be off. Just so you're aware,,,,,:cool:

Thanks for the heads up, I will check it out, I really didn't notice it until I looked at the pic.

TT ya still there ;).:) Is she running cool after this weekends 97 deg weather Happy Motoring now that was hot :yes: Mine ran 190 deg crusing and 200 sitting

Jerome, my wife is nuts! We went to Oregon last week and drove back Saturday. We floated the Deschutes river. Then drove to Mt. Hood and stayed in the Timberline Lodge. Then went to the nearby amusement park. (I bungee jumped twice and zip-lined) (No, never did it before. That's why I did it.) But my wife is the crazy one. Get this: Temps never below 90° and as high as 105°, her car is an '06 Solara convertible. The WHOLE trip was with the top DOWN! I baked, and I'm a sun freak! But at least the air conditioning was on. Crazy. Next time I take a cab.

Jerome, my wife is nuts! We went to Oregon last week and drove back Saturday. We floated the Deschutes river. Then drove to Mt. Hood and stayed in the Timberline Lodge. Then went to the nearby amusement park. (I bungee jumped twice and zip-lined) (No, never did it before. That's why I did it.) But my wife is the crazy one. Get this: Temps never below 90° and as high as 105°, her car is an '06 Solara convertible. The WHOLE trip was with the top DOWN! I baked, and I'm a sun freak! But at least the air conditioning was on. Crazy. Next time I take a cab.

Oh Fred too funny ,sorry I am laughing with you ,there is a differance ...I baked both days in my Camaro tring to put miles on it I did put almost 80 on her ,so now i have almost 200 since I finished her in May ,above 60mph I have Harmonics happening so I need to trace it down ,my first though is Pinion angle ,it does it on accel and decell ,clutch ingaged or disingaged,so I will start process iof elimination tire bal. run on jack stands ,get a mag protractor and check P angle ,not worried thing runs GREAT handles awsome ....Yah but it was HOT ,OH yah TT sorry didnt mean to hijack ,but you aint here ,I got parts for you 10 % stocking fee monthly :D,:yes:Fred Happy Motoring

Fred oh Fred are you out there ??????? with the weather change s/b no overheating prob ha 97 to 58 deg and rain ,I have no prob comming to work in this stuff talk about a 6 week summer ha one of the shortest on record member summer of 93 I nthink we had 2 weeks of sun and record rain and low temps ...oh no sorry again TT ,so do you want them parts ???? Happy motoring