ok give me a clue becouse I am out of ideas,Just finished a project for a friend a 68 chevelle I built a std. bore 350 ,iron heads performer rpm intake and camshaft 9.3 to 1 comp. just a good sound sbc combo. new water pump, griffin alum. rad. 16" elect. fanand it is overheating. not bad or very quickly it just creeps up and keeps going all the way to 250 deg. after about 15-20min. it does not matter sitting still or running 60mph down the road.have checked cam timing,ign timing with or with out thermostat w/160,w180,w/195 thermostats all to the same result. if any one has any more ideas please let me know.

Too lean?
Bad temp gauge?
Fan not stong enough?

:confused:

I had the same problem with my 454, turned out the electric fan was turning in the wrong direction so it was taking hot air off the engine and shoving it through the radiator, it wouldn't cool down at highway speeds just like yours. To test it turn the fan on (close the hood) and take a clean shop rag by the top corners and cover the grill, it should suck the rag onto the grill and not fall off. After I switched the leads to my fans the temp has not gotten over 200. Good luck!

ok, the fan is pulling thru the radiator inthe right direction and it' the big flex-a-lite 16" 2016cfm version.I may be too lean I am running a holley projection fuel injection system that I am fine tuning and have not had someone else to drive while I monotored fuel air under driving conditions. but I have got it dialed in at idle and every way possable that I can check while sitting still. but I can monitor fuel air at idle and be right on the money w/fan running and it will still creep on up the temp.gauge and it is a new autometer and I have checked the temp. w/ a temp gun and it is reading correct.

How big is the temp drop on the radiator hoses? Get it warm (above 180) and feel the difference between the upper and lower hoses. Don't burn yourself and stay away from fan blades or belts! Just a quick feel is all it takes as the upper will be really hot!

If both feel too warm to touch while it's running, then your radiator or fan is not doing it's job. Focus on them some more.

If the upper is nice and hot and the lower is NOTICABLY cooler, then your fan and radiator are working fine. Start looking at coolant restrictions in the engine. It's what everyone hates to check for, but also check for bubbles in your overflow tank coming out of the overflow tube. If there are, it's head gasket time.

You could also have some air trapped in the system as well. I've yet to find the "perfect" solution for bleeding the cooling systems without going to an aftermarket water neck specifically designed for this purpose.

I'm also battling some cooling issues right now, and hopefully they will go away tonight!

Do you have a shroud on that fan or just flush mounted to the radiator? A shroud will help out quite a bit.

If you have all of the necessary equipment in place, i.e. fan shroud good water pump and radiator. Focus on the ignition timing and the fuel delivery. This has always been the result of my overheating problems when no other solution made sense.