GCH

I have 6 blade fan in my 88 and a 7 blade in the 98.
Have read that the 7 blade should move air better but feels like the 6 blade moves air much better when both cars idlng. The 88 have also fanclutch
and more curved wings than the 7 blade. Maybe the
6 blade is some aftermarked ???

The 7 blade in the 98 without ac and fanclutch have
more flat wings.

69CSHC

Many factors at play.

First and foremost pecking order. As this 1973 chart below shows. There's a clear bottom of the line to top of the line. The better the model, the likely better the options, etc.



Then there are options that dictate variances within the same models... The ultra base 67 Cutlass with 330 I owned came with a 4 blade no shroud no clutch. My 69 Supreme (small block) came with AC. And has a 7 blade, shroud, and clutch.

7 blade is the best period, other things may be in play to indicate otherwise.

69CSHC

Here are pics of my setup, as you can see the curve/angle to the blades is severe. So much so that from certain angles it appears to be missing blades. I would assume factory improvements over time are in play as well ...

jaunty75

If there was ever much ado about nothing, this is it. The fans that are in your cars is not dependent on “pecking order.” It is dependent on several things, including what specific engine and what options are on the car and what all this means in terms of keeping the engine from overheating.

You don’t say what years are your cars, but your profile says that you have a ‘65 Dynamic 88 and a ‘65 98 convertible. Assuming they have their original engines, both came standard with a 425 cubic-inch V-8. In the 88, the engine has 10.25-to-1 compression ratio and the 98 has 10.5-to-1. The 88 has a 2-barrel carburetor while the 98 has a four-barrel.

Most importantly, the 98 is a convertible. I’m going to guess that that means that the car does not have air conditioning. That would explain why there is no fan clutch. My ‘73 Delta 88 with a 350 V-8 does not have A/C, and it also does not have a fan clutch. The fan on this car is only four-blade.

I’m guessing your 88 does have air conditioning, and that would explain why there is a fan clutch. I have both a ‘77 and a ‘78 Toronado. Both have a 403 engine, which was standard. Both have air conditioning, and both have 7-blade fans with fan clutches.

Unless a fan was damaged, there is no reason to replace it with something aftermarket. The designers of these engines included a fan appropriate for the situation. I wouldn’t try to second-guess them. As long as your engines operate propertly and don’t overheat, I would not worry about the fans.

jaunty75

There are no missing blades. If there were, the fan would be unbalanced, and you would know it in an instant the moment the engine started. Your fan has three groups of two blades. I've seen that before. The groups form a Y, and there is a gap between each group of two.

GCH

Thanks for pics Phil

Yes i did not write the year when it shows in my profile what cars and year i own. The 88 have factory AC and the 98 does not ,
have mount a fanshroud who i purshased from a member here . It was only a fan protecting plate original. The reason i ask is
that i had some overheating issues in the 98 but not inte 88. But this this overheating issue are better now when using
Termocure to remove rust in the engine and flaps around the new radiator.

Both cars have the 425 engines you mentioned .

jaunty75

Overheating can be caused by many things, and it's usually not the fan. Remember, the fan is only effective at low speeds or while the car is sitting still with the engine running. At highway speeds, the movement of the car forces air through the radiator and cools the fluid. The fan at this point is not doing anything, and the purpose of the fan clutch in cars that have them is to disengage the fan from the shaft so it can spin freely (freewheel) and not take power from the engine to turn it. This is why cars equipped with A/C have one. The air-conditioning system takes engine power which can cause an engine to run hotter, so relieving the engine of one of its loads by use of a fan clutch helps in keeping it cool. With non-A/C cars, the load in running the A/C is not present, so there is no need to remove the fan load.

If your car overheats at idle but not while at highway speed, the fan could be the problem. But if it overheats going 60 miles per hour, the problem is not the fan.

GCH

Thanks for answers about this , we,ll se how everythings goes this year. The overheating
issues in the 98 was only at idle / low speed in traffic jams. Works great all other times.

android 211

The irregular fan blade spacing made the fan quieter. Some 500 Cadillacs had 6 blade fans however most HD cooling systems had 7 blade fans and a clutch.
Some fans have a more severe angle to them because maximum air flow is desired at a lower rpm.

cfair

Glenn,
I wrestled with this problem for a very long time until I was happy with how my 1966 98 worked in California traffic on a hot day. I hope this post helps you.

First up, the 1965 "fan shroud" wasn't really ducting any air at all, it was more of a hand protector so no one got their hand in the fan. Here's a shot from a junkyard car:

1965 Olds 88/98 with radiator missing so "shroud" is clearly visible:

Hopefully this saved some hand injuries, it could not have helped cooling very much.

In 1966 Olds made either 1 or 2 types (can't recall if Toro's were different). Either way, the Cutlasses and big cars all got the same shroud which worked in the smaller cars with the narrower radiator, but in the big cars, the shroud didn't cover the full width of the rear of the radiator. I always considered it Olds "cheaping out".

Here is a factory diagram of the 1966 Olds shroud with a note on the modification I made to mine by adding the left half or so of a later (1968 or 1969) Toronado should on the left.

How to mount a 1966 Olds shroud (radiator removed to make it easy to understand)

In my 66 98 (No air conditioning), here is how it looks from the driver's side:

Modified 1966 shroud in 1966 Non-A/C 98 convertible.

The rubber front curtains are also very important for cooling. I remade mine in the factory shape with a little artistic license using masticated rubber from Fusick. I think they're tied in with Zip Ties, or maybe I used the factory pins, I can't recall. Here's a diagram which shows the bottom one, but oddly, it doesn't show the ones on the side. I even put a curtain between the radiator top and underside of the metal plate to be sure all air gets forced through the radiator core.

1966 Factory diagram of radiator front curtain. Only lower is shown. Dashed lines are where the side curtains go in front of the radiator affixed to the radiator support

Put rubber curtains on top, below and on the sides of your radiator to force incoming air through the radiator core for better cooling.

Next up is your original question. I use a 7 blade fan with clutch fan even though my car originally had a 4 blade fixed fan as delivered.

These days our California gas is less good (I can only buy 91 octane) and we have many more cars on the road here than in 1966. When I use my old cars, I can expect to sit in traffic most days and cooling needs to work right. Also after an engine rebuild our V8's can run hotter since they may be bored out to have a little less metal than they were delivered with new. Not even talking about plugged up passages and so on.

Here is a screen shot of the Hayden brand clutch fans I figured would fit my 1966 big cars:

2019 Hayden fan clutches that fit 1965 and 1966 Oldsmobiles.

If I remember right the highlighted model 2797 is the one I'm using either on my non-AC 98 or on my AC-equipped Starfire. I believe I'm also using the 2765 model on one of my cars. Lighter duty fans make less noise, but don't cool as much as heavy duty.

As a result of all this research, I wound up with a the front of the fan clutch pretty tight against my radiator:

Experts recommend ~1" from radiator core to fan clutch front.

Finally here's a shot of my modified 1966 fan shroud. It's not the prettiest hack, but it works well:

Make up for 1966 Olds cheapness by adding half a Toro shroud to your 1966 factory fan shroud for complete radiator coverage.

The final minor physical tweak I did was to put TrimLok bulb seal on the leading edges of the shroud for a positive seal against the radiator. I'm not sure it was necessary but I had it lying around and thought it might help.

Chemically, I put distilled water and yellow antifreeze in my cars with 2 cans of "Water Wetter" secret sauce which supposedly helps cooling. I use 70% water and 30% antifreeze, but it's warmer in San Francisco than Sweden. I'm sure your mix would include more antifreeze.

Hope that helps!
Chris

GCH

Thanks you all for tip about this when i got the car it was just an 8 inch sheet metal on top of the
radiator to protect from fan i belive , have not seen other "shrouds" than the one i have . I have flaps
on top and on the sides front of the radiator.

Many here uses electric fans to help in front of the radiator when cruising around with low speeds and
many stops and idling for hours.