Bad to hear that you are having troubles...great to hear from you, Gaba.  Hope you and the family can make the bash.  Nobody EVER misses two in a row.  LOL.

BB

I had exactly the same issues with the same fixes including the hi flow water pump in until I put in an electric fan. Now if I stay below 80 mph it runs in the normal range. I ran it at 90 mph for about 30 miles and it started to get hot. When I slowed down it cooled down. The engine turns 3000 rpm at 80 mph. The difference is my engine is a 351W bored .030 over and stroked to 416 cui. I like the electric fan but MS says I need a new mechanic. I don't know what else to do to it except slow down the rpm.

Have you had the heads off the car recently, if you have it is possible to put the head gaskets on the wrong way causing overheating. You haven't mentioned it so I will assume no, just throwing that out there.

Could try replacing the thermostat. Might be that its not opening all the way. Didn't see it mentioned that you replaced it along with everything else. Also check to make sure that your radiator cap is seating in the radiator good and that the spring pressure is still good. A 11 to 16 pound cap should be sufficient with all the mods that you have done. Finally the coolant should be a 50/50 mixture. Pardon if all this seems obvious, but the last two affect the boiling point of coolant.

If you are concerned with maximum cooling, then use pure distilled water with a bottle of Water Wetter or Purple Ice. Water transfers heat better than ethylene glycol. MachTJ stated that you should use 50/50 which protects the engine from freezing down to -40 degrees, but he lives in Wisconsin where it can actually get that cold. In North Texas 25-30% glycol is sufficient for the winter and it transmits heat better than 50/50.

Did you bleed the cooling system?  People make 100 changes chasing a heating issue and never bleed the system.

Last edited by TremendousWand (8/18/2017 12:06 PM)

I use distilled water and just a "dab" of antifreeze mainly for the lubrication it gives the WP. (1 dab=20/25%!)Doesn't get REAL cold here either! 
I fill radiator about 3/4 full and let idle with the cap OFF until I see the thermostat open (water in radiator starts rolling/swirling/puking) then top off with antifreeze.
I have flushed my engine/radiator/heater with Dawn detergent...drain/rinse/drain/rinse.
Can't imagine yours is yukked up enough for a  major flush!?!!
6s6

Just a word of warning - I have had two Flowkooler pumps and both were bad within 5 miles of driving the car. Actually, on the first one the bearing went out after 5 miles. On the second one, the bearing was toast straight out of the box. They are having some serious quality control issues right now and I wouldn't use their pumps if I could absolutely help it.

Instead, you might try putting on a stock pump with the correct impeller. A lot of aftermarket pumps have just the star-shaped impeller, which apparently cavitates water a lot more than a closed-vane impeller. I've had good luck with a plain old stock HiPo pump.

Do you have a good temp gauge on your car (i.e. better than the stock idiot gauge)? If so, when you're driving, pay close attention to the temps. If it fluctuates around a lot even when driving normally (even if it's fluctuating within acceptable spec), you're looking at air in the system or a thermostat malfunctioning. I had a thermostat that got stuck partially open so it would overcool in cool weather and on the highway, but overheat in high load or idle conditions when hot out. Really annoying.
 

Well, that's good news then - you can rule out the thermostat or air in the system as the issue. 

If you do get the Flowkooler pump, inspect it VERY carefully before you bother to put it on. You shouldn't have any play in the bearing at all and it should feel perfectly smooth. Anything less than that and you should send it back because you'll lose it real quick.

I've also heard good things about the Edelbrock pumps which are comparable in price (IIRC) though they don't look perfectly stock.

I'm currently on the road with my '66 and the HiPo pump has been perfect in every situation. FWIW, the only thing that is different from a stock pump on a Flowkooler pump is the impeller - instead of an open vaned style, they use a closed vane style (like the HiPos) with 16 vanes. That's kind of what led me to the HiPo pump in the first place.

Ya know that if its a lack of air flow at idle and not water flow .... it's a perfect scenario for a good electric fan.
Just saying.

could be timing at idle, Not enough BTDC timing can make the motor heat up at Idle.  Do you have vacuum can on that MSD dist?

Last edited by mxjeffb (8/20/2017 6:38 PM)

mxjeffb wrote:

could be timing at idle, Not enough BTDC timing can make the motor heat up at Idle.  Do you have vacuum can on that MSD dist?

timing was set by MS himself.. after a lot of playing around.. its running cooler than it used to now.. more than ever!! lol

vacuum advance and msd 6al box

well yall may be right.. that these cars did overheat.. but i still see so many people without these issues on similar setups.. nyway.. its a good shot at fixing this before going electric if i need to