sbc overheating. 650hp rated aluminum radiator

Put the sending unit in the head, or in the intake manifold next to the thermostat. The head location will get hotter, the intake location will tell you how hot the coolant is when it's ready to go to the radiator to get cooled off.

What gage is it?

220 is ok on engines older than the 90s too....they're pretty much the same engines, after all.

 

If the fan was set up to push and it was installed to pull, The first thing you need to do is flip the blades around on the motor, Second thing you need to do is switch the wires going to the fan. The clues you gave indicate temp ok at running down road . temp high at idle or in traffic. Air flow is the problem. texs1935

 

do you have any pics of the set up is the rad inlet the highest point in the system, make sure theres no air in the system!

Not that I think your stupid but is the fan blowing the correct direction?

 

Never EVER have I solved an overheat problem by slowing anything down. NEVER!

The OP's issue is a small radiator and insufficient airflow at low speeds. 190-210 with a 16 psi radiator cap is normal. 50/50 mix of modern anti-freeze and water is all you need, the rest of it is snake-oil.

 

If that fan is a Zirgo it's from the beloved Hoffman groups and not worth a dime. Piece of crap and the rating is utter bull. I'm thinking air flow at low speed is the issue,

 

Quoted and emphasized for absolute truth!

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Needlouvers and I experimented with a Zirgo (POS) fan supposedly rated at 2800 cfm or some other made up number. When it didn't perform close to half of the rated air flow, a call was made to them. They mentioned unrestricted airflow at 48 volts or something similar. So in other words, shit stained sales pitch.

 

I doubt the radiator size is too small. My radiator is a Griffin 16"x17"x3" with two 1" rows, and it cools my approx. 400hp 327 just fine with a 160 stat, and a dreaded pusher fan. I run right at 185-190 all the time, idling or at speed. My fan is the biggest, highest cfm I could find, and I think that is the difference.
I'd find a larger cfm fan so you're moving as much air when idling as you are moving down the road.

 

AND, absatively the reason I will never, never, never, never, never run an electric fan on a hot rod again!!! I don't know if Elpolacko remembers this, but that same summer saw me put three different fans in the Plymouth, all by different manufacturers, all died horrible deaths in the Phoenix heat in between 2 weeks and 2 months... Problem solved by going back to my big old fan clutch and Cadillac 7 blade fan and my shroud...

 

Run a 190 thermostat, antifreeze, and a good rad cap.

If that isn't enough, figure out how to put an OEM puller fan on back.

 

wow....this is a crazy thread. lol. drove the truck over 45 miles today. drove great. at one point my gauge maxed out at 250....

the guages are omega kustom. the temp sending unit came with the guages but was freakin huge. the only plug i could find that was the correct size was located in the water pump top side. the fan i believe is doing just fine now on the cfm rating. almost all 17" fans are rated 1700-2200 cfms regardless of the brand or manufacturer. im not sure on the brand of mine. i can NOT install a fan on the back of the radiator because i have a little less than 2inches between the rad and the water pump pulley the thinnest fan i could find was a 2.5 inch fan. if i could run the original clutch fan i would. i love the clutch fans! but sadly i can not in this setup. i do believe the temp gauge is reading wronge and im not looking for a infared temp guage or some themometer to stick into the radiator fins.

thanks for the input guys!
also ive tried making the carb run richer and the truck just stumbles on itself. timing is also dead on. so i can rule those two out also.i will post pictures here in a few mintues of everything. thanks

 

Is that the sender that came with the gage? or is it some other sender? Gages need to be used with the correct sender, or they will read wrong. Anyways...where it is located is where the cool water from the radiator goes back into the engine. Which is not very helpful, assuming the gage is actually working right.

Is there any way to move the radiator forward a bit?

 

Simply put, the water needs to spend more time in the rad. If you do not want to run a thermostat, at least slow down the flow at the thermosatat housing. Use an old thermosat with the centre remove or a large washer. The cooling all happens in the rad, the coolant has to be there long enough for it to do its job

 

This has always puzzled me. If it's flowing too fast to transfer heat to the radiator, how come it wasn't flowing too fast to to allow heat transfer from the block and heads?

Bob

 

tstat was installed. its 160degree. i picked low temp since im not running a heater that way the engine will warm up faster when first started. inwhich it did just that.

 

yes its the sender that came with the guages. the radiator is installed in the factory location. i can not move foward any because of hood latch

 

Check to make sure you're getting a good ground to the sender.
You didn't wrap the threads with Teflon tape did you?

 

i dont know if it matters or not....i noticed when i turned on my cooling fans inside the cab on all my gauges moved about 1/4 one way or another. why would turning a fan on inside my cab to cool me mess with gauges that are not hooked up to them? could all this be because of bad grounds?

 

You betcha'! You can never have too many grounds.
Poor grounds are like gremlins.
Ground the sender and see what happens.

 

how to i ground that temp unit then? that sounds kinda tricky. dang...i hate electrical work!!!!!!!!!!!!!!!!!!!!!!!!!!1

 

i am 64 and here is what my mentor told me at 16 if heatsup at idle it is an airflow prob. if it heatsup at speed it is coolantflow. now with that being said and reading your last post isuspect somthing is going on with the gauges. take it and have it checked at autozone or somewhere and have it checked with an infrared meter and see wher you are at at the very least you need t-stat and coolant tom

 

Some type of alligator clip on one of the brass hex heads with wire run to a good ground.
It's just temporary.
Also refer to my post #28 to know for sure what the temp is.......like studebaker46 said.

 

If you slow down circulation, how do you get it to spend more time in the radiator without also spending more time in the engine absorbing additional heat which increases the BTU load on the radiator?

Bob

 

The gage/fan problem is probably due to voltage drop, not bad grounds. The cure might be to add a relay that gets it's power from the battery itself, not from the main wiring harness.

A voltmeter and some careful thinking should help you figure out what's going on. You can measure the voltage between the battery - terminal and the gage housing to test for ground problems, or between the battery + terminal and the gage power connector to see if the voltage is dropping too much. Anything more than a couple tenths of a volt is too much.

 

any particular relay i should buy? i dont have any installed. now that this has been mentioned its got me wondering because every late model car ive ever seen has mutiple relays and such inwhich i know atleast one is for electric fans if equipped. what is currenly going thru my head is that the electric fan mounted on the radiator might not be recieving FULL voltage and running at lower CFM's and resulting in the overheat.....well. ive got alot of investgating to do. i will post my findings.

 

One possibility; http://www.flex-a-lite.com/auto/31147-99936.pdf

Bob

 

How about a pic of your fan setup?

When it got to 250F on the gauge, was it popping out your overflow, what lb cap do you have on the radiator?

I have a 15-16 lb cap, 160 stat, old ass 26x17 radiator, single 16" puller 2.5 inches deep. Before it got to 90F here, I could be anywhere from 175 to 185F on the highway which was nice. Fan would come on in traffic at 205 or 210 (commanded), and take it down to 190F. Now my system cannot handle 90-95F in bumper to bumper traffic. Have seen 225-230F on gauge still was not popping but I just can't drive it like that makes me crazy loco. Once my car gets to 220F it cannot really get it back to 195, I'd have to drive a long time to cool it down.

I think I got my fan from http://www.the-fan-man.com/shop/-c-33.html?page=3&sort=2a&osCsid=79b5cb86ac59063d9827a5b1a9181ada I have to find my receipt.

Had to mount it offset to avoid water pump.. Pic from a while ago, I'll try to take some better ones today:



I have 2-4" gaps all the way around my radiator.

I believe my solution is to get a new 2-row aluminum radiator (yep will paint it black), block off all air gaps on the side and bottom, and I really would like to run two electric fans if I have the room. But I also picked up a Lincoln Mark VIII e fan that's another popular swap fan.

Good luck I read all these overheating threads like crazy.

 

Have you used the external thermometer[turkey thermometer from a grocery store in the rad core] to see what temp you are =ACTUALLY= running at??? you may be perfectly cool and not be getting an accurate read from the guage....BTW never heard of the guage brand ,and in 40 plus years in the trade I wonder just how good are tose guages???
If Stewart Warners are even- not all- good.... then possibly?????

 

I see no mention of what pressure radiator cap is being used...."220" degrees, with a 15 lb cap is well withing acceptable "limits".

Using a 50 / 50 mix, water / antifreeze, a 15 lb pressure cooling system will boil at 227 degrees. Each 1 psi will raise the boil point by 3 degrees, so in this case, the real boil point would be 257 degrees. 3 degrees X 15 lb = 45. Add that to the 212 degree boil point, and it becomes 257 degrees.

With those pressures and temperatures, car mfg stopped using "real" numbers on the temp gauges, because the buying public thought there was a problem.

When installing temp senders, the "bulb" must be as "submerged" in the coolant as possible; Using more than one thread adapter moves the bulb farther away from the coolant flow, and result in low readings. <I learned that, the hard way...>

Happy Roddin'
4TTRUK