Thread: cooling
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Old 07-09-2013, 07:10 AM
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Join Date: Jan 2012
Posts: 628

Originally Posted by wmeabates
If You have some extra pulleys try a smaller one on the pump,or a bigger one on the crank.That will speed the pump up.Maybe both but don't exceed the rpm limit of the fan blade,very important. Sometimes less mechanical advance in the dist. and more advance at idle will help at low speed also.Bill.
This is the "toe dance' I spoke of earlier . . You say, one, "it's always done it" . . and if you run up the rpm to 2500, it cools down . .

This means . . You're pulling enough air through the radiator to cool the radiator you have currently at 2500 rpm. You need either more air, or more radiator. Now, "more radiator" doesn't necessarily mean a bigger one, but one that's more efficient. And what works in one application doesn't necessarily fit another. You're dealing with efficiency of convection here.

IF . . you overdrive your water pump to compensate for the lack of radiator, you will still have the same volume of cooling fins but you'll be flowing coolant at twice the speed you have now . . Which will cause heating at both ends of the rpm spectrum.

Here's the Temps you should be looking for on a SBC . . with a 180 thermostat, @ the Gooseneck; 185-195 . . Back of Radiator at the top hose inlet;195-200 . . at the bottom hose or engine inlet; 140 . . This is the important one! Get it right and the rest will fall into their right places.

Bill hit on another thing you might check, but I'm sure you already have, and that's timing. If it's retarded below about 10 at the crank, SBCs will heat at lower rpms . .

One more thing . . Location of your sending unit. Ideally, it should be in the Left head in the plug location right behind the #1 header pipe . . If it's in the reverse side between 6 & 8 or at the gooseneck (on a lot of later GM Cars) you'll get hotter readings at lower rpms, dunno why, other than ambient surrounding heat. The sending unit or plug at #1 in the head will read about 155 if the engine heat at the thermostat is 180 . .

IF . . you get the radiator right and the correct speed of coolant the mechanical fan will do just fine . . until you decide to put all that neat stuff that racing engines have where the fan would go. Then you'll need the biggest "S" style electric fan, preferably with a manual switch, you can get . . BEHIND the radiator . .
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