[Lee]

You list the first troubleshooting item as:

*A lean air/Fuel Ratio (Also check fuel pump and Filter) - ELEC PUMP, NEW FILTER

But do not say if you've verified the AFR. At the least, what do the plugs look like?

Also a 204 @ 0.050" cam with 9.75:1?? That is a cam I'd consider if the CR were 7.75:1.


You might also want to cut open the oil filter, and make sure it isn't full of bearing pieces.

[noalibi]

test stand has 1-16" electric fan w/o a shroud, and a hi flow squirrel cage shop fan (all run time is on my engine test stand)i cant figure out out to attach a pic...says wrong format so working on that. i will check for the 30 degree drop as a measure of cooling....Thanks TOM S for the tip

[noalibi]

Originally Posted by Lee

You list the first troubleshooting item as:

*A lean air/Fuel Ratio (Also check fuel pump and Filter) - ELEC PUMP, NEW FILTER

But do not say if you've verified the AFR. At the least, what do the plugs look like?

Also a 204 @ 0.050" cam with 9.75:1?? That is a cam I'd consider if the CR were 7.75:1.


You might also want to cut open the oil filter, and make sure it isn't full of bearing pieces.

-will check plugs
-CR based on table with stats on butler site with 16 heads, -6cc heads, & .030 bore
-why do you suspect i may find material in oil. all clearances and specs were well within tolerances. oil pressure good, and engine is not real stiff (tight). i did buy a spare oil filter to check and will to verify. i take all reasonable input as credible, thanks.

[noalibi]

i've been going on wisdom shared to me by my dad 40 yrs ago that If your car is overheating in park then you need a bigger fan, if it overheats on the freeway then you need a bigger radiator. i am going to install a factory fan and shroud first, and after that i guess a bigger radiator. i bought the champion a year ago (same as in the car now with a stock 455) for the test stand so what should i try next...rodney red, griffin, ?, they get real pricey sometimes.

[tom s]

FYI,in my 69 firebird with a factory 350 auto radiator and V8 pontiac engines from 366 to 455 and everything in between it has never over heated.Factory flex fan and factory shroud.It has a small fan pulley and std balancer pulley. Tom

[HWYSTR455]

A 16" fan is no way enough, probably only is 2-2500 cfm at best. That's your problem. Am very sure of it. (I've tried a lot of fans)

Try this one:

https://www.summitracing.com/parts/der-16927

Or one that is similar that fits over as much of rad core as possible.

Putting a shop fan in front of it helps some, but not enough to make a reasonable drop in temp.


,

[Formulabruce]

Originally Posted by HWYSTR455

A 16" fan is no way enough, probably only is 2-2500 cfm at best. That's your problem. Am very sure of it. (I've tried a lot of fans)

Try this one:

https://www.summitracing.com/parts/der-16927

Or one that is similar that fits over as much of rad core as possible.

Putting a shop fan in front of it helps some, but not enough to make a reasonable drop in temp.


,

Ever see a FLAT surround on a JET engine INTAKE? , or exhaust?
Getting "more fan" can cover more radiator, but NOT all with the FLAT "shroud"
THe HP needed to run those fans is MORE that a stock Clutch fan would use, and that does NOT restrict ANY air.
IT amazes me that Simple Wind dynamics and air movement, and even hydro dynamics cant seem to make to Under the hood of a car in the aftermarket.......
GM engineers DID the Homework. in 1970 Ram air IV cars were tested in the Desert....
If anyone questions GM and fan shrouds just look at a '71 or '72 Grand Prix...
GM put a WIND TUNNEL in that car.....

[HWYSTR455]

It's not flat shrouds that are the problem, it's flat shrouds that are too close to the core.

I have that fan on a 535ci with AC and a 495ci (Olds) with AC, both run right at the stat, +5 degrees in extreme conditions.

It also has pressure reliefs to allow more air flow at highway speeds.


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[nUcLeArEnVoY]

Originally Posted by HWYSTR455

It's not flat shrouds that are the problem, it's flat shrouds that are too close to the core.

I have that fan on a 535ci with AC and a 495ci (Olds) with AC, both run right at the stat, +5 degrees in extreme conditions.

It also has pressure reliefs to allow more air flow at highway speeds.


.

This. A flat shroud that is too close to the radiator core will only dissipate heat effectively from the area of the core directly behind the opening for the fan itself, while the rest of the radiator core will be poorly exchanged. That's why shrouds are ideally conical in shape. In that case, you'd almost be better off running no shroud.

The whole point of a shroud is to maximize the surface area of the core that is to transfer heat in the presence of a fan that is not able to cover the entire surface of the radiator. The shroud effectively traps the heated air inside of it so that it can be extracted by the fan away from the core, thus dissipating the heat. With a shroud that is too close and is flat, the suction of the fan will not be able to grab all of the heated air from the entirety of the core; while on the other side of the coin, no shroud at all means the fan is grabbing a mixture of ambient air as well as air from the radiator core that contains transferred heat. No shrouds are great for highway travel, not so good for low speeds/idle.

[RocktimusPryme]

I switched from factory non AC pulleys to AC pulleys and it made a big difference on my car.

[Formulabruce]

If Flat worked, GM would have used it LONG ago. People compensate for the "Flat" by more, or more powerful fans.
Olds never have had a heat issue like Pontiac.
The radiator can never be as efficient where there is a Flat "shroud"is , even if the flat is 2 inches away, Vs the fan area.
When Fan shrouds were developed Gm engineers put like 50 vacuum gauges on their test car, all over the shroud, to get an idea of total area performance.
If Flat worked, and took up less space, they would have used it.
Try to find a flat funnel.
I understand the public has been duped by all this and its so easy to open the catalog and buy new stuff.
Most times the factory set up actually works.

[Sirrotica]

Look at race cars that run on a closed course for more than 13 seconds, you won't see any electric fans on them. I have no idea of why people think electric fans are superior to an engine driven one. They will not ever move the amount of air that an engine driven one will, and the aren't linear with heat production generated by RPM change.

Running a Pontiac on a dirt track will challenge anything you think you know about keeping one cool. I had to do some unorthodox things to keep mine cool, but when I got the system optimized, you would never see 180, no matter how hot, and humid the ambient air was.

Engine driven fan, with a RV style composite fan blades, 2, 3 core radiators back to back. A/C pulleys. As much radiator area as possible, and a fan that will pull as much air as possible through the radiator and shroud system. The composite fan is very light (11 ounces) has a near 90 degree pitch on the blades, so you run direct drive, no clutch. Even at idle it pulls a huge amount of air.

Not having a cooling system that could remove heat as fast as it was generated, cost me a brand new fresh engine. Having to completely rebuild a new engine that ran only 1 race, is a hard way to learn to have a cooling system up to the job. Expensive lessons are the hardest to swallow, but you won't forget it.

[RocktimusPryme]

Its not that electric fans move more air than big engine driven fans. Typically they dont. However, most people whose classic cars are set up even close to correct only have a problem at idle or stop and go traffic.

At these low RPMs, a good electric fan will still be giving its max air flow where the engine driven fan is limited by the low RPM of the engine. So if someone can get more air flow at the area where their vehicle actually needs it, AND save 10-12 HP by switching to electric. Its an easy choice.

I say this as someone with a clutch fan setup running cool. The pitfalls of the electric fan is that people cheap out on them and get units that arent sufficient at any RPM.

[HWYSTR455]

Originally Posted by RocktimusPryme

....... The pitfalls of the electric fan is that people cheap out on them and get units that arent sufficient at any RPM.

That's the number one reason electric fans get a bad rap.

Number two reason is a toss-up between poor wiring and/or shroud design.

If you don't have a specific reason to switch, then by all means, stick with a mechanical.

I switched for multiple reasons, one being amp load of accessories. Once you go beyond a certain amp load (EFI, electric pump, big stereo, etc), a V belt can't handle the alt load. I've found that right around 150a is the tipping point. Solution: serp belt setup.

Another reason I switched was as mentioned, stop & go/low speed for extended times. I daily drove my car for a long time, in stop & go traffic, with AC running in 100+ degree weather.

With 2 fans, the shroud has less impact, the areas of 'vacuum' overlap, and make up for some of the poor designs. Can't really think of a good way to put that, but there it is.

There are also advantages over mechanical fans when using a PWM controller, you basically only use what you need with those, regardless of RPM or vehicle speed. Can even use them when the engine isn't even running.


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[Scott65]

Or shut them down at speed, when/if they're not needed.

[Sirrotica]

I've also run the composite engine driven fans on street cars. You can leave them idle for hours, they won't get hot, and driving 11 ounces of nylon fan, the only energy you use, will be to move air.

There is no free lunch, the amount of electrical energy you use to run the alternator to run the fans is taking power from the engine at idle also. and why do I care how much power I use at idle?

For whatever reason Pontiac engines have always been tough to cool. You can run a SBC with a electric fan and it will never get hot. Try the same thing with a Pontiac, and it will run hot. It just takes a much higher heat transfer of BTUs on a Pontiac.

There are few well engineered electric systems that are going to cool a Pontiac V8. By the time you get a pair of fans and a shroud that will cool one, you're using just as much electrical energy as a light composite engine driven fan, plus the composite fan is $30. They don't make a 19 inch fan, but the 18 inch fans have worked well in the past for me. Space them properly in the shroud, and they'll pull plenty of air at idle. Flex a lite has been making these fans for at least 45 years that I know of, and they work very well.

https://flex-a-lite.com/18-inch-nylon-fan.html

I want to drive the car and look through the windshield while I'm driving, not keep looking at the coolant temp gauge to see if the electric fan is able to keep up with the engine. Even when Pontiac engineers were trying to eek out the last bit of mileage by lightening things on the 301/265 engines, like making the timing chains and gears 2 rows thinner, and running aluminum hoods on the B body cars, they never resorted to running electric fans to save fuel.

My 05 GTO has electric fans, and a large aluminum radiator, but it also has an LS2 aluminum engine, nowhere near as hard to cool as a Stratostreak engine is. If I took a GTO cooling system from a late model GTO, and tried to cool a Stratosteak engine with it, I'm certain that it wouldn't be up to the task, the capacity of the system just isn't there.

If you ever wanted to run a large aluminum radiator and electric fans, the late GTOs have a heck of a system already engineered, but I doubt it would cool one of the dinosaur Pontiac V8s adequately. It does fine on a LS2 with A/C, but I just don't see it working on a 350,400, or a 455.

Someone that is industrious, and has access to used late model GTO parts could prove me wrong, someone should try it. Good science project, and around here there are a lot of late model GTOs being parted out, so parts shouldn't be hard to come by.

Myself, the juice ain't worth the squeeze.

[HWYSTR455]

Originally Posted by Scott65

Or shut them down at speed, when/if they're not needed.

Yup, I shut mine off at 65mph. They are also off under 160 degrees.

.

[TRADERMIKE 2012]

Mikes Reply:

See this Thread that is going on now!

https://forums.maxperformanceinc.com...50#post6336050

One thing I agree with is that the Fan Blade, on the conventional Factory set-up, should be sticking out a little past the inner Shroud so the tip grabs some air under the hood, I believe this allows the blade to spin better with less resistance?

[FrankieT/A]

Originally Posted by nUcLeArEnVoY

One good electric fan I've heard positive feedback on is the Flex-A-Lite #295 (116524) with dual 13.5" fans. It pulls 4600 CFM of air, but more importantly the shroud for each of the fans is slightly conical like what is seen on most modern car fan shrouds, and so it's not perfectly flat up against the radiator core like the terrible Cold Case ones I've heard about.
.

I use this fan and its the first electric set up I've ever used that actually cycles. It pulls an amazing amount of air. I have it set to go on @ 188* and off @ 180. When it kicks on it drops my temp to 180* within a minute or so. My car can idle with the A/C on indefinitely. With A/C my temp never goes above 192* on a 98* day.

[HWYSTR455]

Originally Posted by FrankieT/A

I use this fan and its the first electric set up I've ever used that actually cycles. It pulls an amazing amount of air. I have it set to go on @ 188* and off @ 180. When it kicks on it drops my temp to 180* within a minute or so. My car can idle with the A/C on indefinitely. With A/C my temp never goes above 192* on a 98* day.

Yeah, it's like 4600cfm, will suck a beer out of your hand if you get too close when it comes on!

They draw 28a each, 56a total, which is a hard hit on the alt/electrical system. Need to run a controller with it.


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