Hey guys I think I've decided to buy a good flexfan for my 355 with my birthday money (yesterday) and was wondering about what I need to buy since I have learned that nothing really bolts on without buying other stuff to make it function the way it needs to. I've been a little nervouse about flexfans because I've looked at the photos of some of your hoods with a bubble in front. I'd like to keep my head connected to my shoulders too :eek: . will my stock clutch work or should I mearure up for a spacer? right now it is a stock 7 blade. Will I lose/gain water temperature and gain milage and power as well? thanks

Zac, why do you want a flex fan? You'll put more power to the ground with a clutch fan. I run clutch fans on all of mine. A regular non-thermostatic clutch fan offers greater cooling during normal driving, and little parasitic hp loss at WOT.

Thomas

First off, DO NOT TRY TO USE YOUR CLUTCH ON A FLEX FAN. Secondly, IF you do switch, youll need a longer spacer to keep it in teh shroud in the right spot.

IMHO, for anything other than racing, the power loss for clutch vs. GOOD (read Derale) flex fan is kinda negligible. Sure the cheapys ARE JUNK (cheapy flex fans AND cheapy clutches)- but, the good flex fans actually work really well. Im talking street, not racing here.

However, if your clutch setup is working good, Id leave it alone. BUT, if you do have to have a flex fan, get the Derale flex fan. They are kinda hard to find though- and they can be $50 a pop for teh chrome one.

Here's some opinions from one of the most respected water pump companies I know of which I for one happen to agree with ;)
Stewart Pumps (http://www.stewartcomponents.com/html/tech_support/techtip4.asp)

So since it ain't broke don't fix it? I think I'll just stash my cash it until I can get a dual electric set up. The reason I was thinking about the flex fan is I like the shiny suff under the hood and I haven't seen many chrome electrics. Do it right the first time right? maybe I will look into getting my inner fenders plated....hmmmm...... graemlins/thumbsup.gif Thanks again guys

Mike, I know that Stewart is a quality company. I agreed with everything until I came to their comments on clutch fans, which didn't even go into the different types made. Conspiracy theory from the guy who doesn't believe in conspiracy theories: Stewart would prefer that no fan be attatched to their pumps because it will cut down their warranty claims.

Call me crazy, but I've always put more power to the ground with a viscous (non-thermostatic) clutch fan. I do check them from time to time to see if there is any fluid leaks (death to the viscous coupler), and to see if a simple "spin" test shows a smooth consistent, versus jerk and slip, drag as I manually spin a clutch fan while the engine is off.

Modern electric fans, quality ones rather than the cheapies, are the best without a doubt. But was it not just a year or two ago where a magazine test pitted all the different types against each other and found: electric fans #1, viscous clutch fans a close #2, and flex fans near the bottom in regard to power?

Thomas

Originally posted by Bomber '67:
Stewart would prefer that no fan be attatched to their pumps because it will cut down their warranty claims.Im no conspiracy theorist either, but I have to agree with ya! Im not a big fan of clutch fans for my own reasons, but alot of R/D went into them by GM and others. I dont think theyre "not recomended" if at all possible?


Originally posted by Bomber '67:
But was it not just a year or two ago where a magazine test pitted all the different types against each other and found: electric fans #1, viscous clutch fans a close #2, and flex fans near the bottom in regard to power?

Thomas Actually its Car Craft, May2000. I have the articles on JPEG files. Id post the link, but for the life of me cant find where I found them originally!

Actually, the electrics were first. Then the clutch fans (depending on WHICH clutch it had) were next. The HD Derale style fan (the Derale is better- They were using the 10K flexalite fan)was just about even with the clutch fans. It was down by about 10hp and 5 to 10 lb ft at something like 6500 RPM. The rigid 6 blader OEM was the HUGE loser- we're talking 30-40 HP, 20 lbft less! The cheapo flex fan was just above that and the plastic fan (if you can believe that).

"since it ain't broke don't fix it" sounds smart to me, especially just for looks.

Thomas,
I agree almost completely & almost always use viscous fans for street use.
I don't think it is a conspiracy though :D

The deal as I understand it is there are a couple of problems.
First most people don't realize you need to check the unit for leaks & smoothness & second there have been or are a bunch of elcrapo viscous units that were giving them fits with folks buying the pump & still having heating problems so rather than tell people to go to GM or at least not buy the $9.99 unit they just went with the easy route & don't recommend them.
Bit of a cop out as a good clutch unit is in my opinion a better alternative to even electric in some cases.

Thomas, is there any reason you don't prefer the thermostatic clutch fans? I have one I ran on my Chevelle which will be used again when it's back on the road, and another to replace the flex fan a p.o. put on the '59 Corvette. The clutch I have for the 'vette is new and could be exchanged if there is a definite advantage to a non-thermostatic. TIA

Wes, thermostatic fan clutches belong on tow vehicles, trucks, and other sub 4,500 rpm applications - but not on a performance car that will definitely turn more than tow vehicle rpms.

What I don't want is to have a thermostatic clutch engage itself while I am on my way to 6,000+ rpms - that will usually put the fan through the radiator.

You definitely want the fan disengaged based on rpms on a performance application. Usually always, the guys who put a non-worn out fan clutch through the radiator did so with a thermostatic clutch in a "hot" environment that engaged the fan well past 4,500 rpms.

Thomas

Ok Mike and Thomas .. what brand or how do pick a "quality " viscous clutch unit ... will be installed on my BB with Stage 3 Stewart pump and stock 66 5 blade clutch type fan?

How much cfm do you need with electric fans to stay cool on the street??

Thanks for the information Thomas. I'll be getting a non-thermostatic fan clutch.

The best fan clutches are made by G.M., but I've had great luck with several of the aftermarket brands. I haven't bought a G.M. fan clutch for years because they are so $pendy. When I go to the parts house for a new one I check the part out before I buy: 1)is it totally dry, or is there some seepage (pass) 2) does it spin smoothly as I manually spin it? I really can't complain about the aftermarket viscous fan clutches.

Thomas

Thanks again for the advice Thomas. I live within a few miles of two PAW stores, so I should be able to check a few out this weekend.