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Old 04-14-2020, 12:21 PM   #278
TA_C10
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Join Date: Jun 2018
Location: Texas
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Re: 1968 GMC - Ol' Blue

Quote:
Originally Posted by MDPotter View Post
Hope everyone had a great Easter!

So I knew the fans that came on my radiator were cheap and destined to be replaced soon so I went ahead and did it. I bought this radiator and fans on eBay and the fans were advertised as 1,228 CFM each. Through some research, I found them on Amazon for $20 a piece from a company called UPGR8. I compared them to a Spal fan rated at 1,200 CFM and noticed that the Spal fan pulls double the wattage and that confirmed for me that they are falsely advertised. Interesting that the eBay seller has since revised the details in the item listing to not indicate any fan CFM. So anyway, I bought these Spal fans rated at 1,451 CFM each. Wired them up, worked as they should and definitely moved a lot more air. It took several minutes at 3,000 RPM to get the engine up to high temp for both to kick to full speed. I noticed that running them full speed that the volt meter would drop by about 1 volt (down from 14) and the fans would slow a little bit for a couple seconds, then return to normal. This happened every 10 seconds or so. I'm not sure what's that about, but later that day I stumbled on some info on the internet saying that Spal fans are not supposed to be ran at half speed/half voltage. I wanted to hear it from Spal so I called this morning and sure enough, the tech rep indicated that it would "prematurely" wear out the motors running them in series. So I guess I'll be rewiring my fans so that one fan is on full speed when the engine reaches low temp and then the second fan kicks on at high temp (also A/C high pressure). This is the case for Spal fans, but I don't know about other manuf's. I just assumed that this would be okay since GM does it, but the fans GM uses must be designed for it. So we enlarged the holes in the shroud and I was happy with the fit and quality of these fans.

Also replaced the front shocks due to the increased drop from where I had it originally.




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