"Different" kind of overheating

[ludwig]

I'd check out the coolant level and flow first. Have the radiator boiled out. You could also have a lot of the radiator fins blocked with bugs over the years. This has happened to me in the midwest. Get a good water pump and a 160* thermostat. Be sure to purge the block too with some kind of coolant cleanout thing and water.

Then go after all those other more recondite failures. Just to add to the frowst, I think you might look at a too lean fuel mix condition because this causes heating under load.

 

[johnnyzoom]

Thanks for more ideas. For my situation, again as of 9 months ago, new 3 row rad, water pump, hoses, thermostat (180, have thought about going to 160 next summer), rad bled correctly, TDC established, timing at 12, trans cooler in front of rad. This is the only time I've had this problem, trying to keep it from happening again. Truth is I really don't have much opportunity to drive over 70 mph, but I'd like to know I could and that things are right.

I have noticed in the past that it's sensitive to timing and running hotter, have kept an eye on that. Maybe try advancing it a little more?

think you might look at a too lean fuel mix condition because this causes heating under load.

This is a good possibility, was running rich due to loose carb, corrected and may have retuned a little too lean. Plugs don't indicate that but may take more time to show.

I thought electric fan robbed HP but was a negligible amount?

Thanks

 

[rommaster2]

I thought electric fan robbed HP but was a negligible amount?

Thanks

No thats the regular fan. Also it raises in how much hp is lost at highway speeds because the faster you go the more drag the fan creates on the engine. An electric fan runs off of the alternator, taking less hp.

 

[80broncoman]

At that speed I don't think a fan is even needed.

 

[63comet]

I have to agree with Bronco, I have an electric fan with a manual switch and even in the summer this year, I would shut the fan off when running along at cruising speed, and the temp guage even dropped a little. I believe that the fan is needed for slow driving and stops at lights.

 

[66 Fastback]

With all those new components, it should have no problem running 90 mph let alone 70 mph without overheating. You mentioned the timing is set correctly. Is the timing advancing fully at the higher engine rpm's? If it is a Load-matic distributor, you could have a bad diaphram or stuck linkage or an incompatible carburetor. If it is a later distributor with cntrifugal advance, you could have a stuck mechanism, or springs that are too heavy and or a bad vacuum diaphram. Have you mapped the ignition advance versus engine rpm to know that you are getting proper advance at the proper engine rpm?
Doug

 

[johnnyzoom]

Have you mapped the ignition advance versus engine rpm to know that you are getting proper advance at the proper engine rpm?

I'm going to have to go through the whole ignition system, I think I may have cheated way back when I dropped a new dizzy (load-o-matic) in there and adjusted spark plug wires to compensate for being off a little. You remember being new to this and being anxious to get a car on the road and running? Might be guilty of a little of that. But I'm reformed now.

I'm also starting to suspect slipped harmonic balancer, as it seems now I have to run with lots of advance just to keep running.

Like some have suggested, going to do some back to basics work and see what I can find.

Thanks for all the help