roadkill2

An electric fan won't cure your problem . . Or at least, they generally don't . . nor will a different water pump.

Low speed heating tells me that you aren't flowing enough air through the radiator, or . . The radiator doesn't have the convection tubes necessary to carry enough coolant through that radiator.

When did this heating problem start? What did you change before it manifested itself?

I'm not being a hardass, but you sound like you're ready to spend a bunch of money to keep the problem you have right now . . .

Another thing. If you're just going to drag race it, start with an adequate radiator, and then put a single electric fan on it that covers the whole radiator back with it's shroud. NEVER put the fan in front of the radiator . . Simply because you put all the motor and shroud supports in front of the fan and cut it's efficiency by about a quarter . .

markdunlap

You can pull a lot more air thru a radiator with an electric fan than you can push. Your creating a low pressure area in the direction air wants to go anyway.

Pushing air with circular fan thru fins is like trying to push on a rope.

hotrod1994

well it always gotten hot at an idle ive tried 180 t stat the 160 no t stat at all and its always gotten hot at an idle, i can hold it 2500 at a stand still and it will kool down to 190-210 and stay there as long as ive got it at around 2500 if i let it idle it heats back up

i dont see the radiator being my problem as my old man ran a stock 2 core brass/copper radiator with a flex fan in his nova with a big block that ran 10.50's in the 1/4 ran a steady 220 temp, my 3 core aluminum has got to be better than an old brass/copper 2 core

so i should get a fan to pull air through the radiator is what you guys are saying?

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.

itsabird

Yep also check carb settings, i would also drop the flex fan, they are designed to reduce drag on the engine, imo with smaller blades, coupled with any flex that may happen at low idle. low speed cooling, is compromised.

roadkill2

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 . .

itsabird

Are you useing the edelbrock carb?

hotrod1994

ok well im gonna have to start figuring out what the problem is
and its a holley
thanks guys

hotrod1994

how should i go about checking the the temp at the bottom hose on the
radiator? ir thermometer?

and the flex fan is 3-4 inches away from the radiator so ive got a felling its not getting enough air flow

TheYellaBrick

HO KAY now we're getting the real skinny here. Flex fan at 3-4 " even WITH a tight shroud will not pull enough airflow at idle. I might have missed it ,but I don't see where you even mention having a shroud at all. SHROUD-SHROUD-SHROUD properly fitted and no more 1/2" clearance at the blade tips.