I just want an opinion on which set up will have better cooling potential. I have both set-ups, 6 blade clutch fan and the original 4 blade to the Non/AC 350 Olds Cutlass.I have the 4 blade mounted now. Mostly in town and Country cruising around with limited highway use. Wouldn't it make sense a 6 blade would push more air as compared to a 4 blade?? I been having this debate with someone who thinks the 4 blade is better for stop and go, getting stuck at long lights type driving were my temp gauge usually starts to really climb past 225 but fine when moving.

 

A clutch fan and a shroud would be the preferred setup for cooling. However, the 4 blade fan should work for your car unless the engine has been modified. Reasons for overheating could be poor radiator condition, thermostat not opening completely, or tuneup issues.

 

Heavy duty clutch with the six blade and shroud for TOWN DRIVING.

 

Are the fans interchangeable w/o changing water pumps?

 

I had a heavy duty with the six blade on my ride but the clutch almost never disengaged and the sound drove me crazy. Especially on the interstate. I felt like I was driving a Cessna. FWIW.

 

I have a 6 blade non-clutching fan on my 54 and I never notice any roar. I also haven't noticed any significant difference in my water temp. The next step is to add a shroud.

 

I just wanted to note, all shrouds,seals and air dam in place , new 3-row radiator, cap and 185 degree thermo and water pump is fine. Car has been modified slighty with a slightly larger cam. My Carb is at Sparkys getting rebuilt, so the one i am running now is probably running a little lean. i didnt want to get into all the small things which i have read in many a post on here, just a good debate on which fan to run

 

The six blade fan will be more efficient than the 4 blade assuming proper placement within the shroud.

 

Having the seals in place is very important as well. The air must flow through the radiator not around it. If the clutch was always engaged it was a bad clutch.

 

Yeah, I'm not convinced the clutch was good. But it did disengage; it just took forever. Sometime as much as 20 miles on the interstate in 45 degree weather. I ordered it new from JC Whitney.
I chucked it and got the stock clutch and have had no overheating issues.

 

Anybody have an idea how long the Spring is in the lower radiator hose is? Mine seems only to be around 6"-8" long.Just wondering if it should for the most part run the length of the hose maybe around 14"-16"?

 

With a good pressure cap you shouldn't need any spring, but they run the full length of the hose. Good luck

 

All things being equal, more fan blades pull more air, but that is assuming the blades are the same. I believe, of the fans in question, the 6 blade pulls more air, has more drag and makes more noise, hence the clutch for when you don't need it. The old saw goes if the heat problem is sitting at idle, it's an airflow thing, at speed, it's a coolant flow thing.

 

If I'm not mistaken, the spring is there to prevent the hose from collapsing under high-RPM, nothing to do with the cap. Some have said that new hoses are reinforced and don't require the spring, I still use one. If you have a spring that isn't quite the full length of the hose, as long as it's close, within a couple inches, it should be good enough. You can also stretch it out a little bit.

 

The only time you care about the lower hose collapsing is when the engine is warm enough that the thermostat is open. By then, your entire cooling system, including the lower hose, is under pressure -- somewhere between a couple psi to 15 psi (where the cap bleeds it off).


There's no way a water pump can collapse a hose with pressure like that in it. Remember, to collapse the hose it has to not only overcome the pressure but actually pull a vacuum (compared to atmospheric pressure). It will cavitate before that.


If you do observe your lower hose collapse, then either every tube in your radiator is plugged or your thermostat is stuck closed -- which means your cooling problems are not a collapsing hose, it's a bad radiator or thermostat.


Fire away.

 

Just wanted to add that i threw on the 6 blade fan w/clutch set-up and does seem to cool better when sitting at idle or a light Probably has dropped 6-8 degress in some instances staying around 190-205. Thing i have yet to happen is being stuck at a light or Railroad crossing for an extended period of time were it will start to constantly rise up into the 230 + area or at least that's what it did beforeI know my gauge reads high by 8 degress after shooting where sensor goes into the manifold with an infrared.What do you'll think about where my Initial timing should be set? I don't have a dial back timing light.

I have stock motor freshly rebuilt with a slighty larger Comp Cam.

Specs:

72 350 4 barrel Olds Rocket stock rebuild from the ground up retaining stock pistons and 7A Heads.

Stock rebuild on heads also

Comp Cam Part#XE262H-10 was added:

intake exhaust
Duration @.050 218 224
lobe lift .2970 .3000
lobe separation 110.0

Running headers and 2 1/2 Pypes Exhaust with H pipe

Any thoughts and thanks in advance

 

I just saw this post. You make some good points, but I have seen a hose collapse. It was on a dyno, on a warmed up engine with a thermostat I believe. Happened every time the engine went over 3 or 4k RPM. I don't know what pressures the dyno's cooling system develops, and on the car, the system may be under pressure, but if there was no differential fore and aft of the water pump, the water wouldn't move. I'm not a fluid engineer, but it seems all the water pump would need to do is to develop sufficiently lower pressure on the lower hose relative to the upper hose/system to collapse it. And as I said, I saw it happen. Between this and the fact that every car used to come with a spring in the lower hose, I will always run one.

 

The initial timing will depend upon what distributor you have, and if it has a recurve kit in it or not. Factory points distributor should be ~10º initial; factory HEI should be ~20º initial.