Standard vs heavy duty fan clutch

[wpavlis]

So I am building a mild 350 for my 68 c10. I don't want to use electric fans for various reasons. My stock 307 has no clutch on the fan, so I want to upgrade to a fan clutch on the new motor. For some reason the heavy duty ones are 2-3 times the price. Are they worth it? I am going to be using an aluminum radiator and a fan shroud. Thanks!

Bill

[AcampoDave]

Since you live in Arizona I kinda think the h.d model is a good call. Especially if a/c factors in to your plan. I run the h.d model myself and its pretty beefy.

[Dead Parrot]

You didn't mention what fan you are using. If you had a flex fan with the solid connector, replace with a 5 or 7 blade OEM fan.

On my 75 with a stock 350, a standard clutch works fine. I have the 7 blade fan. Never a heat problem, even when towing a boat + ~800lbs of crap in the bed on a 100+ day running the AC.

I found the HD versions fully engaged when the temps were way too cold. Nothing like running at 70 with the 7 blade fan at full RPM when the motor isn't up to temp yet. Could barely hear the dual exhaust over the fan roar.

[70K10Hunter]

Originally Posted by Dead Parrot

You didn't mention what fan you are using. If you had a flex fan with the solid connector, replace with a 5 or 7 blade OEM fan.

On my 75 with a stock 350, a standard clutch works fine. I have the 7 blade fan. Never a heat problem, even when towing a boat + ~800lbs of crap in the bed on a 100+ day running the AC.

I found the HD versions fully engaged when the temps were way too cold. Nothing like running at 70 with the 7 blade fan at full RPM when the motor isn't up to temp yet. Could barely hear the dual exhaust over the fan roar.

this right here. not to mention aluminum rads transfer heat faster.

[AcampoDave]

http://www.haydenauto.com/featured%2...s/content.aspx good reading here. Are you looking at the ones with the thermal control? I have that style of heavy duty. It's a Hayden brand part# 2747 mated to a 6 blade 18" solid metal fan with a 2.5" pitch. I don't hear any excess noise. I'm not saying that the others are wrong, just that mine seems fine.

[wpavlis]

I guess I should have mentioned that I don't have A/C. I Was thinking one of the thermal units. The fan on my current motor is the 4 blade fan without a clutch that gm installed at the factory. I imagine anything will be an improvement there. I will need to pick up a fan as well. 6 and 7 blade fans seem to be the most common type. Is there much of a difference?

Bill

[wpavlis]

Originally Posted by AcampoDave

http://www.haydenauto.com/featured%2...s/content.aspx good reading here. Are you looking at the ones with the thermal control? I have that style of heavy duty. It's a Hayden brand part# 2747 mated to a 6 blade 18" solid metal fan with a 2.5" pitch. I don't hear any excess noise. I'm not saying that the others are wrong, just that mine seems fine.

That 2747 unit looks like the ticket. Only $36 on rock auto.

[68gmsee]

I got a 5 blade clutch fan from the salvage yard for about $40 years ago. I've been using it for years with no problem. Only thing you have to watch out for is the water pump pulley bolt pattern matching.

[Captainfab]

That and one off of a serpentine accessory drive is designed to turn the opposite direction.

Originally Posted by 68gmsee

I got a 5 blade clutch fan from the salvage yard for about $40 years ago. I've been using it for years with no problem. Only thing you have to watch out for is the water pump pulley bolt pattern matching.

[AcampoDave]

I think I read somewhere that fans with odd numbered blades help reduce air turbulence.