overheating

[fryedaddy]

i have a problem that i cant figure out.i can ride around all day with my new 428 at 170-180 degree,but if i run hard through a couple gears it overheats.i have a new 4 row alu rad.any ideas? i have about 500 miles on this new engine and i was just starting to trust it more on longer drives

[fryedaddy]

i forgot to mention that i bought a weird looking thermostat that has a brass cup on the engine side that opens up backwards instead of forward to the rad side?

[fryedaddy]

just got it out for a little ride to see how its doing.i took the stat out and checked it.i have some rust specs and small peices of rust in my rad where the water jackets did not get cleaned on the rebuild.i took my rad off and flushed the rust out of it too.could that rust be causing problems

[shady]

well, overheating can be caused by: A) not enough air flow thru radiator. B) not enough coolant flow thru radiator. C) coolant flowing too fast through radiator, not giving enough time to cool. D) retarded timing. E) bad water pump impeller. just to name a few. I would probably start with the thermostat, replacing it with another one. maybe a 165* & see what happens. Overheating can be a pain to figure out. Mostly trial & error.

[jayb]

Point C) above is a myth, in my opinion.  I've heard all those stories, but they don't make sense from a basic thermodynamics standpoint.  The big issues are sufficient coolant flow through the radiator and sufficient airflow through the radiator.

[shady]

you are probably right jay, I have never encountered it. I remember running restrictors instead of a stat in my sbc, but that was to try & hold some heat between rounds. Old rumors die hard. Now I just remembered I have to get my battery off the cement floor b4 it discharges.

[427LX]

How is the jetting on your carb? If a bit lean it could heat it up.

[fryedaddy]

well its not the timing,i have it bumped up to 40.im thinking its that weird thermostat im using.the top hose with the stat is stiff as a board when hot,but the bottom hose,you can mash it pretty easy.im thinking the stat is closing or restricted

[fryedaddy]

i have a 950 holley 88s with a power valve in front,96s in back no power valve in back but i have jet extensions

[fryedaddy]

i thought it was a little rich instead of lean,but maybe that 950 flows a lot of air and it is lean??

[Falcon67]

Points FWIW -

Multiple cores and aluminum don't seem to mix.  I use two core units, and from what I've been told from cooling engineers the larger 1" cores in aluminum are there because aluminum doesn't have the same conduction as copper and you need more surface area.  What works for copper doesn't work for aluminum.  Multi-cores past 3 in copper lose efficiency really quick. 

You're too cold.  Run aluminum hot - 190 or so.  Makes the heat exchanger more efficient when the temperature differential is greater.

If you are running standard pulleys, when you buzz it up the water pump will cavitate.  That either puts air in the water stream, or reduces the volume of water the pump can move.  This is SOP on the drag strip, nothing special to see my temp run from 190 to 200~210F on a 660' pass.  And that's with a steady 30 GPH electric pump.

[plovett]

Does your lower radiator hose have a wire support in it?  Maybe it's collapsing shut when you get on it hard.  You didn't mention if it cools down after your full throttle blasts, when you drive normally for a bit?  Or does it stay hot?

just a thought,

paulie

[fryedaddy]

my top hose has a wire in it but my bottom hose is soft rubber with no wire.it cools back down but it takes forever

[Nightmist66]

Does your lower radiator hose have a wire support in it?  Maybe it's collapsing shut when you get on it hard.

Very good point.

Point C) above is a myth, in my opinion.  I've heard all those stories, but they don't make sense from a basic thermodynamics standpoint.  The big issues are sufficient coolant flow through the radiator and sufficient airflow through the radiator.

It hasn't personally happened, but have heard of guys overheating with taking the t-stat out and no restrictor. The water/coolant doesn't have quite enough time to transfer the heat like it should. At the very least, I would use a restrictor/gutted t-stat.


I have no overheating issue with a 195° t-stat(high flow Robert Shaw), factory w/p, clutch fan, and factory radiator w/shroud.

[fryedaddy]

thanks for all the ideas.im sure i will figure it out with a little trial and error