Overheating In Traffic

[par4tom]

I have a 61 chevy c10, with the following:

Champion 3 row aluminum radiator
Flex a lite 16" 2500 cfm Syclone electric fan on a 160 degree switch mounted on the inward side of the radiator and in "pulling" mode
Serpentine belt system
Weiand high volume mechanical water pump, brand new.
Thermostat is a 180 degree and works fine

The motor is a small block 383 Stroker doing about 400 hp.

Living here in Central California, the summer days can get really hot and over 100 to 110 degrees. Driving down the road, the gauge reads about 160 degrees. Not bad.

However, I get in traffic and it quickly starts to escalate to 220-240 degrees. Is there anything I can do (a larger fan maybe) to keep this thing cooler during these Hot August days?

[verdell]

I have a 383/700r4 425 HP combination in my '60 and used to have similar issues. From what I understand, Champion Radiators are supposed to be pretty good if you're moving enough air and engine is properly tuned. I finally switched from a no name brand aluminum 2 row radiator and electric fan to a bigger Griffin along with a Lincoln Mark VIII fan and have had zero cooling problems in 100 degree weather in bumper to bumper traffic. I'm sure other guys from the forum can chime in with other possible solutions.

[chevy_mike]

Cooling fine at speed but not in slow traffic is almost always an air flow issue. You need to get air being pulled through the whole radiator and a standard fan without a shroud is likely not going to do it. Also a 2500 cfm fan is not much, especially if not pulling thought a shroud. verdell is likely having good luck because of the Lincoln fan, which is really high cfm rating (IIRC 4400 on high) and I think it has a built in shroud.

[siggyfreud]

The Mark VIII fan does have a built-in shroud, but it doesn't cover the whole radiator. But it was enough for me and the stock radiator to cool my pretty built 350 in bumper-to-bumper on a 95*+ day. That fan MOVES some air. I think I had mine set to come on a 195 and off at 180 or so.

[geezer#99]

Retarded timing is also a heat builder.
What's your timing curve like?

[verdell]

Originally Posted by chevy_mike

Cooling fine at speed but not in slow traffic is almost always an air flow issue. You need to get air being pulled through the whole radiator and a standard fan without a shroud is likely not going to do it. Also a 2500 cfm fan is not much, especially if not pulling thought a shroud. verdell is likely having good luck because of the Lincoln fan, which is really high cfm rating (IIRC 4400 on high) and I think it has a built in shroud.

That's correct Mike, the Lincoln fan and shroud assembly is an exact fit for the Griffin radiator I ordered. The entire surface area of the radiator is being covered with the shroud and so far, I haven't had to even use the high speed.

[par4tom]

When you guys said Lincoln Mark VIII fan, I thought you were talking about an aftermarket company. Is this thing from an actual Lincoln?

Can someone post a link where I can get the correct fan, speed controls and relays?

Thanks again... You guys are very helpful!

[LVPhotos]

I used the Flex-a-lite Black Magic 3300cfm
https://www.flex-a-lite.com/15-inch-...ctric-fan.html

[Lugnutz65]

Originally Posted by chevy_mike

Cooling fine at speed but not in slow traffic is almost always an air flow issue. You need to get air being pulled through the whole radiator and a standard fan without a shroud is likely not going to do it. Also a 2500 cfm fan is not much, especially if not pulling thought a shroud. verdell is likely having good luck because of the Lincoln fan, which is really high cfm rating (IIRC 4400 on high) and I think it has a built in shroud.

Here's a nice web article I found about the Lincoln Mark Vlll fan.

[Clyde65]

http://www.automotix.net/usedautopar...FQataQodc5UNDQ

[chevyrestoguy]

Originally Posted by geezer#99

Retarded timing is also a heat builder.
What's your timing curve like?

Exactly. I was going to post up the exact same thing. If the initial timing is too far retarded, the engine will run hot at idle. Put it at 10 degrees of initial and see what it does.

NOBODY ever looks at timing. A bigger electric fan or a colder thermostat is not always the answer. Two minutes with a timing light can save you a lot of money and headache.

[argonaut]

Thermostat temp makes no difference on cooling capacity, as was said. 160 degrees is typically not advisable because it is not optimal for.combustion. you really want at least 180-200 degree range.

Make sure timing and fuel jetting are correct. As other said, poor timing or a lean condition can cause higher temps.

Make sure you have a good shroud.

You already have high flow covered.

After having a discussion with one of the techs at griffin radiator I now know why the cheaper aftermarket radiator have more cooling issues; it has to do with the size and shape of the passages, not just the number of rows. 3 rows of tiny passages won't transfer as much heat or provide as good flow as 2 row with bigger passages. Food for thought.

As was said, the 2500 cfm fan isn't pulling much air. If you run calcs to see roughly how much air flow you have crossing through the radiator at say 45 mph where you can probably maintain cool engine temps, you'll be surprised that the number is MUCH higher than 2500cfm.

[par4tom]

Ok...in looking your posts over, I went back and looked at my current set up and now...it looks like the problem is obvious.

My radiator surface area is about 24" x 22" (528 square inches) and my fan is a 16" round fan which is just a little bit over 200 square inches. Basically, I am only drawing air through 38% of my surface area. No wonder it is getting hot so quickly when I'm not moving. It looks a lot bigger on the radiator than 40%. But facts is facts!!!

With regards to the timing, the truck is timed at about 11 degrees.

With regards to the radiator, I would concede that to be a problem if it wasn't cooling down so quickly when I'm driving. It was 108 degrees last weekend and cooled down within a minute once I got moving.

My flex a lite 16" fan claims to move 2500 cfm which is the same number the Mark VIII fan moves in the Corvette Forum test...albeit they are both without any resistance. I am assuming that the flex a lite product is legit!


I think my first step is going to be to come up with either a shroud to fit my existing fan or come up with another fan set up that has the shroud on it. I am leaning towards the later on this one...

I'm going to look on Summit this afternoon and see if I can find something that will work. The dual 12" fans seem to move a lot more air then the single 16" fan and appear to have about 10% more surface area. (2 12" fans have 225 square inches compared to 200 on the single 16").

Bottom line, my fan is making noise and moving air...just not enough air through the entire radiator!

Feel free to chime in on this topic...you're thoughts are appreciated!

BTW - Thank you Lug Nutz for the link to the article on fans. It should be in the FAQS section!!! A definate read. And the link to the corvette forum really adds some scientific credibility!

[siggyfreud]

Do you have a link to the corvette forum claiming 2500CFM? I have read a few forums and most of those claim around 3000-3500 CFM on low, and near/above 4500 CFM on High for the Mark VIII. I have seen those numbers on Thirdgen, Modden Mustangs, etc. so I'm curious where it was concluded that they flow 2500 CFM.

Cheers!

[par4tom]

Siggy,
Click on the link in Lug Nutz post called "Web Article"...

On that site, you'll go down past the pictures and see a entry dated July 6th. There is a link called "Test Data"...

Click on it...
T

[Chevy Fleetside]

I went to the Yard today and scored a Mark VIII fan for $32. Now to mount it up.

[T and S]

I think u are right on the money ! If u don't have enough air flow to remove heat well....

[verdell]

Originally Posted by Chevy Fleetside

I went to the Yard today and scored a Mark VIII fan for $32. Now to mount it up.

That's awesome..I think you're really gonna be pleased with it. I saw one last week at a local bone yard in a T-bird but the hood was dented so bad that I couldn't get it open.

[par4tom]

Digging a little bit, I found quite a good bit of information on the Lincoln Mark VIII fan. As a 12 volt enthusiast, anything that is pulling close to 40 and 50 amps of current is either grossly inefficient or a beast! It looks like this thing is a beast...

Here you go

https://www.fordmuscle.com/archives/2006/10/Mark8Fan/

Here is a link from earlier. Be sure and click on the Test Data Link...

http://www.thehollisterroadcompany.com/markviii.html

And some more...http://forums.tccoa.com/showthread.php?t=136722

I could keep going as there is a lot of info on this fan...looks to be the real deal! I'll keep you posted on what I eventually work out and show the differences in cooling both before and after...

Tom

[Chevy Fleetside]

I think I made a mistake. Looks like I took it out of a town car and a mid 2000 car. Probably the same fan but the shroud is different. I am going to see if it fits. It looks like it aims downward so the hot air will not get blown straight into my air cleaner forcing hot air into it.

[theastronaut]

Originally Posted by chevyrestoguy

Exactly. I was going to post up the exact same thing. If the initial timing is too far retarded, the engine will run hot at idle. Put it at 10 degrees of initial and see what it does.

NOBODY ever looks at timing. A bigger electric fan or a colder thermostat is not always the answer. Two minutes with a timing light can save you a lot of money and headache.

We built a '68 Chevelle with a 383 and Champion 4 row radiator, and their dual fan kit. 180 degree thermostat. He had his engine builder "tune" the carb and set the timing. It run hotter than expected, 190-200 idling and driving and would go up from there with the AC on. Low on power too, and got worse as the engine heated up.

We got the car back, got the carb and timing dialed closer to where it should be (his distributor needs an advance kit to get more total advance)... it was running 4* ATDC and the vac can was hooked to the ported vac fitting instead of manifold vac. It now runs 180 after 30-40 minutes of sitting in our 95 degree shop with the AC blasting the whole time, no air flow except the electric fans. Take it out for 25-30 miles and it never runs over 170 while you're moving. Tons more power (it'll chirp fourth with sticky tires) and it starts better too. Only thing changed were the carb adjustments and timing.

[chevyrestoguy]

Originally Posted by theastronaut

We built a '68 Chevelle with a 383 and Champion 4 row radiator, and their dual fan kit. 180 degree thermostat. He had his engine builder "tune" the carb and set the timing. It run hotter than expected, 190-200 idling and driving and would go up from there with the AC on. Low on power too, and got worse as the engine heated up.

We got the car back, got the carb and timing dialed closer to where it should be (his distributor needs an advance kit to get more total advance)... it was running 4* ATDC and the vac can was hooked to the ported vac fitting instead of manifold vac. It now runs 180 after 30-40 minutes of sitting in our 95 degree shop with the AC blasting the whole time, no air flow except the electric fans. Take it out for 25-30 miles and it never runs over 170 while you're moving. Tons more power (it'll chirp fourth with sticky tires) and it starts better too. Only thing changed were the carb adjustments and timing.

Yep, perfect example of the difference when you address all of the little things. Have you ever fired off a new engine and the headers start glowing red within a few minutes? Advance the timing and the glowing stops almost immediately. What happens is that the late (retarded) timing will light the air/fuel mixture when the exhaust valve is opening and the flame goes out into the headers, causing them to glow. This will heat soak an engine and make it run hot at idle (or in traffic). A lean condition can also cause an engine to run warm, but you'll get other fuel-related symptoms at the same time. Vacuum leaks (or in your case, incorrectly hooked up) can cause issues, too. It's the little things that make the difference!

[par4tom]

Astro...Chev...thank you for the post. Mine has about 400 miles on this motor and at about 1000 miles, I'm going to take it for a post break in tune. It runs rich, gets about 8 mpg and smells like it's running rich. I get on it a bit, it dogs it through the mid RPMs but when it gets to about 3800 rpm, it suddenly "catches" and takes off like a scalded ape.

Thanks for the input, I think I'm on the right track...one at a time.
Tom