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Author Topic:   How hot is too hot?
dode
Dirt Freak

Total posts: 417
posted April 26, 2002 11:00 AM UIN: 13209501
How hot would you guys say is safe to run a sbc to before problems might occur? Due to the was the engine was installed in our car (not my doing), we have to run a pretty small fan (14-15") and it worries me. How far can we let the temp gauge go before we have to start cooling her down?

John

jammin
Dirt Administrator

Total posts: 5556
posted April 26, 2002 12:55 PM UIN: 16262997
230-235 in my book

Flatlander
Dirt Freak

Total posts: 310
posted April 26, 2002 01:26 PM
I agree with jammin and make sure you have a good cap

dode
Dirt Freak

Total posts: 417
posted April 26, 2002 01:51 PM UIN: 13209501
That's running temp right? I had it running last night, and it ran right at 200 and stayed there real nice. When I shut it down though, the temp creaped up to about 235, which I understand because the intake probe is in the intake, and the water is just sitting there. This was just in the driveway of course, doing a little final tuning. I have a setup that we can use to spray down the radiator when he comes off, so we are prepared there. Anything else I should look for? Provided we don't get rained out, this will be our first race tonight (blew head gaskets in hot laps the first week). Thanks!!

John

jammin
Dirt Administrator

Total posts: 5556
posted April 26, 2002 02:04 PM UIN: 16262997
Get it any hotter, your gonna run into problems.

jammin

racer17j
Dirt Forum Champ
Total posts: 1565
posted April 26, 2002 04:17 PM UIN: 54865418
i agree with the temps we always have a guy waiting with a bucket or a water bottle to cool it down and we also run a dump valve on the thermostat housing and dump the water out after the race because the water will hold heat in some people disagree with dumping it all but we have seen no problems since we started to do this a few years ago

wam24u
Dirt Full Roller

Total posts: 66
posted April 26, 2002 09:49 PM
If you was at 200* idleing in the driveway, You'll have problems Dode.
You need to get a small crank pulley and a bigger water pump pulley, Uaually you can find these at the junk yard.
One little trick an Ole'Pro showed me, while the car was idleing , put a shop rag against the front of the radiator, if it sticks you are pulling enough air, if not go to the drawing board.
By the way what ended up being you slow cranking problem? I am just curious to know.

blackbart
Dirt Roller

Total posts: 6
posted April 28, 2002 10:31 AM
Hey Dode, I found that a 4 blade fan with a significant pitch (found mostly on older chev/gmc trucks) works excellent at keeping the temp down. The temp gauge never went over 200 after the race (15 lap feature). We did find that we had to go to serpentine belt drive to keep the belts from slipping. Good luck.

redneck bubbas racing
Dirt Freak

Total posts: 213
posted April 29, 2002 07:49 PM
During actual racing 230 is as far as I will go. Under caution I will let it creep to almost 240, then its time to go. After you shut it off I have had it hit 280. I ran 400 with lightweight heads and never cracked anything. Not to say you wont but....

wam24u
Dirt Full Roller

Total posts: 66
posted April 30, 2002 08:35 PM
Be smart and invest in a warning light for water temp. You don't always have time to watch a gauge and I have had them to read inncorrect.

BK19
Dirt Freak

Total posts: 285
posted April 30, 2002 10:01 PM UIN: 40696038
what is the best warning light and how does it hookup(350 chev) is it different then the gauge?

RACER35
Dirt Roller

Total posts: 20
posted April 30, 2002 11:13 PM
ON OUR LATE MODEL (410 SBC) I USED A 220 DEGREE SENDER. I COULD'NT FIND ONE AT THE LOCAL PARTS HOUSE SO I WENT TO A TRUCK SHOP. THE SENDER I USED IS FOR A MACK TRUCK.

Smitty77
Dirt Roller

Total posts: 9
posted May 21, 2002 12:40 PM
Auto Meter makes a nice warning light. You can get them at Summit for about $45 for light and sending unit. Might think about one for oil pressure also.

sideways
Dirt Freak

Total posts: 273
posted May 21, 2002 09:50 PM
I went to NAPA and got a fan switch/sender that grounds out at 227degrees.And used a orange clearence light.And run my hot wire to a gauge switch.

uforacing51
Dirt Freak

Total posts: 349
posted May 28, 2002 05:43 PM
Dode,
Why did you blow head gaskets, is the motor new? or just a used one. If you haven't already, find out why the gaskets blew, you may have more problems brewing. A good radiator and cap should let the engine get to 230- 235 before it starts to boil, water boils at 212 degrees, but once it boils you need to cool it right away, if it continues to run and nothing is done to cool the radiator it will not get cooler ever. That is stating the incredibly obvious I know, but from your description (in the driveway) It got pretty hot for a car just sitting there. Do you have a shroud? the rag trick is a very good tool to see if its pulling enough air at an idle in the driveway. the pulleys are another good step. do you have a thermostat or a gutted one? I have seen guages read bad that were new, make sure your guage is good, and that your thermostat is good. (open it and put a string in it, then boil it in water with a candy thermometer, and watch for when it falls off the string, see if it goes with the temp it is supposed to get to) Lastly, if the motor has been overheated before and burned up, your motor may be in need of a rebuild. after they have been there, they don't get better, unless you rebuild them. Also, make sure your hoses are not collapsing from the water moving thru them to quickly, if you have springs in them make sure they are staying put and if they are the really good stiff hoses than all the better

[This message has been edited by uforacing51 (edited May 29, 2002).]

WesternAuto17
Dirt Freak

Total posts: 248
posted May 29, 2002 08:39 AM
I've heard both sides of this now, how do under-drive pullies help with cooling? I heard they hurt you by slowing the waterpump.

uforacing51
Dirt Freak

Total posts: 349
posted May 29, 2002 05:47 PM
Stock water pumps were designed to work best at 2000 rpm or thereabouts. At 6000 rpm the pump is just cavatating (creating a hole in the water and nothing moves) by underdriving the pulley, at 6000 rpm the pump is only moving at say 3500 or 4000 rpm rather than 6000 and the water moves more efficiently.

dode
Dirt Freak

Total posts: 417
posted May 30, 2002 09:24 AM UIN: 13209501
The head gasket was just a fluke...we got that taken care of now. It runs great. We changed fans to a 16" factory flex fan from a 79 Ford LTD and it doesn't get warm at all. We also did a little work to the shroud, but I think the fan change is what cured our problems.

John

uforacing51
Dirt Freak

Total posts: 349
posted May 30, 2002 11:13 PM
COOL!!!!! L O L

ray14
Dirt Full Roller

Total posts: 67
posted June 21, 2002 11:03 PM
i run a 6 blade flex fan and a 3 core radiator,i also took an old thermostat cut the center out and put it back in the housing to slightly restrict water flow,at idle my car never gets above 180 to 190,if ur water flows to fast through the radiator the fan cant cool it,it has to be cooled to keep engine cool

racer17j
Dirt Forum Champ
Total posts: 1565
posted June 22, 2002 01:28 PM UIN: 54865418
get a solid fan those flex fans will flatten out at higher rpms they are designed to be run at lower ones like you run on the street i ran a flex for a long time and always have temps alittle higher than i likes after i got a solid no more problems

o5racer
Dirt Maniac

Total posts: 115
posted June 23, 2002 10:34 AM
I have run a stock vette pump 1-1 with the crank for 6 years now. 6" crank and 6" WP pulley. i run a 18" plastic 6 blade fan with a good shroud on a griffin radiator. stock thermistat with the center cut out. runs 160 sittin still 200-210 on a hot day.
this is on a 12-1 358 turning 6000 RPM. i also dont have the grill cut out of the nose. i think a good shroud will make more difference than anything.


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