overheating

[thrill22]

having a problem keeping the motor cool, am on alky, have a restrictor in now, need to know if it would be better to put a smaller hole in or take it all the way out, please give me your imput, thanks

[backspace]

I always took the center out of a thermostat and used that,,,,,,be sure the radiator hoses have springs in them to keep them from sucking shut,,,,and be sure you are jetted right,,can't believe you are in trouble with alky though,,,,If you used a radiator that came from an auction,,,maybe the issue there also....if you blow a head gasket in these engines,,they pressure up the aluminum radiators and "bulge " the cooling tubes and leaves no room for air flow,,,seen it everytime when used junk is used.

[thrill22]

radiator was brand new at the end of last year, both hoses do have springs, i was told once about re-jetting the carb, may be on the right track there, gets about 230 when its hammer down

[Confused?]

Have had better luck without any restrictor.

[thrill22]

just run nuthing at all, ive heard that as well.

[johnny v]

I would look at the carb and jet situation...... the problem with alky is usually getting heat into a motor ....... not getting rid of it....
Your lucky you didn't burn a piston...... I would look at the plugs and see if you have any aluminum specks all over the electrodes..... alky plugs are a pain to read correctly before the piston goes away....

[JustAddDirt]

Alky plugs are backwards from gas.
Black....lean
White and clean....rich

I always ran a 180 thermostat to get heat in motor when I ran alky. motor would barely reach 200 if hammer down.
Typically an alky motor, unless really lean will struggle to build heat.
be careful on removing restrictor. depending on quality of water pump, you can, on a stewart, it will flow so much, you would have to restrict it.

[Dirtrunner35]

I also run a 180 thermosat just to get heat in the motor

[Egoracing]

You can not flow to much, the aluminum radiators heat transfer rate is MUCH faster than iron. Even Stewarts web site says not to use a restrictor.

[Renegade Cust Susp]

I think what JustAddDirt was refering to is not a volume problem "flow too much" as much as he meant a speed/flow rate issue. If it flows too fast the thermal transfer will not happen, it has to stay in the radiator for long enough to allow heat exchange.

[backspace]

Do you run reduction pulleys or are they 1 to 1?

[mudslinger47]

It can be as simple as just a bad fan. Been there done that. If you have already overheated with your present radiator, it may be junk too, but 230 isn't that bad, shouldn't blow up a rad at 230.

[Renegade Cust Susp]

Really??

IF its staying in the radiator longer then isn't it also staying in the block and getting more heat transferred into it?

That eventually the entire point in the exchange. Block in water is cooler than the water jackets and draws heat out of the casting as it flows through. Obviously the water can flow so slowly that it doesn't allow for proper transfer just as it can flow too quickly to allow transfer of heat. Its all about exchange.

Fan blades can loose pitch at high speed. The all metal gm truck style 4 blade fan is about the most efficient and most durable you can use.

Also running lean will cause what you are seeing.

[Egoracing]

If it flows to slowly you will boil it and get gas pockets and hot spots in the block. The aluminum of the radiator can transfer heat 4 times faster than Iron. So you could put the water thru the radiator 4 times faster than the block and you would get equal heat transfer. Fast moving water will not allow steam pockets to happen as easily. Go to Stewarts pumps and read up, there is a lot of good tech information there. He recommends pump speed around 6000 rpm, no restrictor and a single pass radiator. The amount of flow area in a regular radiator is greater than that in the engine block so the water is already slower thru the radiator without anything added.

[MM90]

If it flows to slowly you will boil it and get gas pockets and hot spots in the block. The aluminum of the radiator can transfer heat 4 times faster than Iron. So you could put the water thru the radiator 4 times faster than the block and you would get equal heat transfer. Fast moving water will not allow steam pockets to happen as easily. Go to Stewarts pumps and read up, there is a lot of good tech information there. He recommends pump speed around 6000 rpm, no restrictor and a single pass radiator. The amount of flow area in a regular radiator is greater than that in the engine block so the water is already slower thru the radiator without anything added.

Not going to disagree with your statement. But if all that is true then why are there double/triple pass radiators, water restrictors, hundreds of belt/fan combinations that people all claim that works for them?

[Bubstr]

I guess there is always more than one way to skin a cat, but the guy that said heat exchange is the key is close. Looking at the Physics of the problem, the weak link is exchanging from water to air in the radiator. Lots of air threw the radiator is what's needed. Too fat a radiator can slow it. A big fan can help on low speeds but hurt by blocking air at high speeds. Close fins in the radiator clog with dirt faster and restrict air flow. Too far apart and you lose surface area.

As with most race car stuff, there is a balance or compromise. The high Pitch 4 blade fan works, because it pushes air threw the radiator at low speeds but does not restrict the air flow at high speeds. The 2 pass radiator works better than a 4 pass because it don't clog as easy and offers less restriction. Anything you can do to get air threw radiator rather than around it helps too.

[oldtrackchamp4x]

Got a buddy i race with that had identical problem. All he did was build a shroud and his temp dropped an honest 30 deg. Make sure when you build shroud it is sealed around rad, and the most important thing is that half the end of the fan blade is inside the shroud and the other half is outside the shroud. JMO