I have a 69 chevelle with 383(mild) a be-cool big block radiator and a dual electric fan from flex-a-lite.( 25-4600 cfm..2,000 something rpm). I have vitage air also. Where I live it is about 95 degrees average summer day. The motor idles and the fan responds fine and stays in the temp. range. The minute I drive the darn thing climbs to 250 degrees and I have to shut her down. I am thinking that the vintage air radiator is blocking air from getting through to the main radiator. I am loosing my mind.....any ideas....? HELP...all idea's welcome.

Thanks

I have a 69 chevelle with 383(mild) a be-cool big block radiator and a dual electric fan from flex-a-lite.( 25-4600 cfm..2,000 something rpm).

Thanks

2500 cfm or 4600 cfm?That is quite a spread imo.I understand your concern..there does not appear to be an industry standard for aftermarket electric cfm flow numbers.I am wrestling with the same issue.There appears to be some common concensus though..10 amp draw for every 1000 cfm.FWIW..I have to get out of my flex-a-lite dual 12 inchers..they claim this fan kit is for v8 engines making 250 hp.If memory serves correct..they are rated at 2400 cfm combined and only yank 14 amps.I am swapping to derale dual 13 inch that pull 50 amps at 1650 rpm and are rated at 4000 cfm.Seems more true to me.Anyone that boasts 4k cfm and low amps is most likely static testing them for sales only imho.

Here is the spec. Sounds like what you are saying might be true. I have a 540 (700 hp) in a elcamino and I am using a single Derale and it will do the job barely. I was going for a clean smooth look in the chevelle.
Thanks
Part #
292,295/298 puller
Mounting Surface Required
17½" x 27½" x 4"
Fan Diameter
Dual 13½"
Fan RPM @13.5VDC
Variable 1260-2100
Number of Blades/Fan Blade Angle
8/26°
Airflow-Cu. Ft./Min. at 0º Static Pressure
2760-4600
Amp Draw
16-28
Mounting System
Universal Bracket
292 Custom Bracket (Chevy, GMC)
295 & 298 Universal Brackets
Adj. Thermostat 160-240 degrees
Yes
298 does not include thermostat
Air Conditioning Relay
Yes
298 does not include relay
Variable Speed Control 60-100%
Yes
298 does not include controls

There you go with that amp draw(16-28).I am sticking with Dan @Alumitech with the 1 amp/100 cfm or 10amp/1000cfm recomendation.based on that asssumption..the 28 amp motor =2800 cfm.I myself need an honest 4k cfm at slow speed with my blown unit and the 50 amp 4k Derale is not an issue with my 140 amp alt.

Agreed that many fan manufacturers use very optimistic CFM ratings.

I also run in your climate. I saw a big difference when I went from factory 4-core radiator over to a aluminum 2-core radiator.

Also watch for area of radiator covered by fans and/or plenum design. I believe my current setup suffers from smaller fan area compared to OEM single fan design. I plan to convert to a single large 18" electric fan from a Mustang GT and see what difference it makes. They use this fan to cool the 390 HP Mustang Cobra, so it can move some air. But I otherwise have no specs on it.