I cannot get behind that fan clutch discussion

[BillyDeluxe]

Hi folks,
my 65 has a bored 350 and a overheating problem. Especially during the summer month when I get into high traffic.

I am working since quite a long time to get it fixed. I switched the radiator to an original Harrison which I bought from the States. I played a little bit with the rate of cooling fluid. I also bought an original Shroud but unfortunatelly it does not fit anymore as my engine and drivetrain is a mixture of Blazer rear end and 80s C10 truck engine (don't know where there 350 tranny is from). So all slipped a little bit forward and there is not enough space anymore for the shroud.

My actual idea is to rework the radiator with a high performance net and to switch to a clutch fan instead of the 19" fixed one what I have now.
I read much about clutch fans and advantages and disadvantages but I really cannot get behind it so I ask for your help.

A clutch fan operates at a lower speed than the shaft when its disengaged. As soon as it engages it works on a speed of 60%-90% of the shaft depending on the clutch (Thermal/heavy duty/severe duty). But all in all it work slower than the shaft, right?
Okay I agree that it frees a certain level of horse power but I am sure it's not that much.

So why switching to a clutch fan when it's slower than the fixed one (apart from the horse power topic)?

Can anybody give me guidance here?

[geezer#99]

When you say original radiator do you mean for a 6 cylinder?
Can you post a pic of your motor for us?

[jchav62]

If you can somehow find a shroud that works, it will help greatly.

As for the clutch fan thing... it also reduces engine noise slightly.

[MikeN]

The factory clutch fans have more blades, wider blades, and blades with more pitch, so they move more air even at lower speeds.

My 64 C10 has a pretty powerful 350, and it cools just fine with a Modine replacement radiator that is listed for a 64 C10 with 283ci V8 and a GM clutch fan set up for a 69 Chevy Malibu. I happen to own a 69 Malibu, so I test-fitted the Chevelle stuff on my truck to ensure proper fit before ordering.

If you are running a 6-cylinder radiator, that is part of your problem. The V8 radiator is much wider. It sits on top of the frame rails, as oppose to sliding down between the rails, and it therefore sits higher in the engine compartment. You need the V8 upper and lower mounts to install the V8 radiator.

Engine tuning can alos affect overheating. If your ignition timing curve is wrong, or your carb mixture too lean, these can cause overheating.

[BillyDeluxe]

I have no pic of the radiator at the moment but it's the 3 core radiator out of a 65 C10 with a 283 engine. It's original Harrison brand and it sits in the higher rails.

Don't you think this should be sufficient for a 350? I know that the bore could cause overheating but this is unfortunately the only thing I cannot change.

[198plus]

I have always liked a 7 blade clutch fan with a 37 degree pitch, I think they are pre 72 models. Also what do you have your initial timing set at and are you using you vacuum advance, it can have alot to do with cooling issues.

[Dunenutt]

Summit sells aluminum fan shroud kits. They have a pan that you cut out for your application, and a bolt in ring. I just bought one, but it should be showing up today so no review. They have many sizes that will fit almost anything.

[BillyDeluxe]

Does someone of you know if the 60s Impala Fan shrouds fit to the truck. It looks like it could fit and it be screwed to the radiator core very easy.

Any idea?

[padresag]

sometimes there are a lot of little things that are overlooked. pressure cap. how many lbs pressure and is it working properly?
what are you running for coolant?
waterpump. correct dia pulleys
are you running the orig guage and sending unit. have you tried an alternate temp guage.
is it the guage reading that is giving you a problem or is it actually overheating and losing coolant?.
there is one way to run an orig shroud to be effective and that is to have it mounted in the rear frame holes and have a short water pump and remaining setup to go with it
ron

[gimmy 64]

i agree with Ron alot of other things can go along with over heating motors. one big one is check timing. to much advandce it will run really good but will have alot of real driving problems. does your truck have problems starting when hot?

[awbrown]

if it is only running hot at low rpm/mph like stop and go traffic , it may be an airflow problem ... This is assuming that everything else is up to par ,I have an electric fan and as long as I am doing 30 or so mph I have no problem... In traffic I can hear the fan cycle and see the temp gauge go down ... having the proper shouding for the fan and shouding in front of the radiator makes a big difference to...

[Rich 5150 69]

It all boils down to a shroud...no pun intended, make, beg, borrow, or steal one, but you need one. A full shroud and use a clutch fan or fixed fan.

[BillyDeluxe]

Originally Posted by gimmy 64

i agree with Ron alot of other things can go along with over heating motors. one big one is check timing. to much advandce it will run really good but will have alot of real driving problems. does your truck have problems starting when hot?

Absolutely not. It starts always very good.

[jimmydean]

You can make a shroud out of fiberglass, there is a write up on it here somewhere.

[Rich 5150 69]

Are you still runnng the current setup now in your truck on this pic, if you are remove the fan spacer and put the stock style shroud on and all your problems should go away.

here is the stock shroud .....

[padresag]

Originally Posted by Rich 5150 69

Are you still runnng the current setup now in your truck on this pic, if you are remove the fan spacer and put the stock style shroud on and all your problems should go away.

here is the stock shroud .....

I fully agree about the shroud, but what if he does all that and he still has a problem?
ron

[Rich 5150 69]

I`m still guessing Ron but he only has trouble in traffic, same as I had in my `37, I still do but I have no room for a fan ( unless I move the engine back ) and no room for a shroud, so I have a pusher electric, in traffic I have issues, anything above 25 it runs at 170-180.

[padresag]

Originally Posted by Rich 5150 69

I`m still guessing Ron but he only has trouble in traffic, same as I had in my `37, I still do but I have no room for a fan ( unless I move the engine back ) and no room for a shroud, so I have a pusher electric, in traffic I have issues, anything above 25 it runs at 170-180.

I remember my early ford days. I had more problems o/heating with flatheads then I did with o/h in them
he hasn't answered any questions yet, to eliminate anything that could be basic. under 15lb pressure and a 50/50 mix water won't boil until 279 degrees F and if he has a faulty cap and straight water it will boil at 212f. this is where the variables can come in. say that his guage is calibrated for max at 212f and could be comfortably operating at 250f and no problem under pessure, but the guage is saying that he is running hot and it could vary in traffic-Up, but still not be a problem. old systems-new systems
Just like tempers flare much easier these days with people , morso than they did years ago. People are much more sensitive than they use to be. at one time, you could call someone a sob and it was like pinning a medal on their chest; not any more
ron

[BillyDeluxe]

Originally Posted by Rich 5150 69

I`m still guessing Ron but he only has trouble in traffic, same as I had in my `37, I still do but I have no room for a fan ( unless I move the engine back ) and no room for a shroud, so I have a pusher electric, in traffic I have issues, anything above 25 it runs at 170-180.

Hey Rich. You're absolutely right. Above 25 mph I have no problem. Only when I get stuck in traffic it overheats. Normally it runs at 160F once it overheats I am very fast at 200F or more.

What I think it could help is what I plan now. New net for the radiator, switch to clutch fan 17"-19" and heavy duty fan clutch (I have a amgauge TempGuard TFC-49). Hopefully this helps. I am really struggling to get this done since quite a long time. I would never buy a car with a bored engine. It would be much better to switch to a 327 without any modifications. But such an engine is very expensive here in Germany. Everytime when I see Junkyard pictures here I wish I would be in the States. ... (And I've never been there, what a pity!) ...

[BillyDeluxe]

Originally Posted by Rich 5150 69

Are you still runnng the current setup now in your truck on this pic, if you are remove the fan spacer and put the stock style shroud on and all your problems should go away.

here is the stock shroud .....

I still have the same setup except from the fan. Now I am running a 19" Flexalite Steelblade Fan. Everything else is the same.

[FreakyMalo]

I've had better luck with a stock clutch fan setup than with a solid-mounted flexfan and a fancy dual-electric. A shroud makes a world of difference, especially at low driving speeds. A high volume water pump helps too.

Probably a minor point but does anyone have experience running full manifold vacuum to the distributor advance? I've never tried it but have heard that moving it from the timed port (and re-tuning the engine) will help it run cooler at idle.
Here's some discussion on my 2nd favorite forum.. reply #4
http://www.jalopyjournal.com/forum/s....php?t=567069&

[fasteddie1964]

Found a neat DIY link on making your own fan shroud.
http://www.cadvision.com/blanchas/54...FanShroud.html

[BillyDeluxe]

Very nice links to build a custom radiator! I'll give it a try!