[mgarblik]

The parts I had been waiting for finally came today. Spent a couple hours fitting and testing. I have the heavy duty 2747 clutch not the severe duty 2797. Couple of reasons for the choice. The Hayden tech info recommends the severe duty clutch with fan blades of 2.5" pitch or more. That may be why some people are unhappy with this clutch if they are using a 2" pitch or less fan blade. My 6 blade fan has a 2" pitch. The severe duty clutch has so much viscous clutch surface area compared to the heavy duty one, those blades may not offer enough resistance to declutch them. The clutch valve may be functioning but not enough driving force to clear the channels out. Also I bought the heavy duty clutch so less weight would be hanging out front, especially with the 1" spacer I thought I would be using. Turns out, not using the spacer because the factory shroud is made at an angle when installed. About 75% of the blade is in the shroud from the center to the bottom, and about 30% or so is in the shroud at the top half. That's just the way it's made. Fits the radiator and core support prefect. Now I know why the finger guard for the shroud equip[ped cars is 2" longer. It makes sense now. Anyway I ran the clutch everything stock and it stayed de-clutched too long for my taste. Water temp was 200-205 before it really clutched up tight and moved maximum air. When it's clutched, the 19.5" 6 blade fan really moves tons of air and drops the temperature right back to 180. I took the tang out of the fixed slot and rotated it about 5 minutes of clock position as mentioned in an above post and just let the tang rest against the stop outside of the slot clockwise. Put it back together and ran it some more. Now the clutch begins to clutch at 175-180 water temp and I was never able to really get it to clutch all the way up. These were static tests in the driveway. It's in the mid 90's here every day though and I could not get it to run over 180. That was letting it run at a steady 2500 RPM's for about 1/2 hour. I will do some more testing over the next couple weeks with an infra-red heat gun and get some air temps. Happy so far.

[gto19]

Mgarblik

Good info !

If I read your posts correctly you say to move the spring clockwise which would tighten the coil up but when I look at this picture provided in the chevelle link you can see they actually loosened the coil counterclockwise. So what’s the correct way to move it ?

[mgarblik]

Originally Posted by gto19

Mgarblik

Good info !

If I read your posts correctly you say to move the spring clockwise which would tighten the coil up but when I look at this picture provided in the chevelle link you can see they actually loosened the coil counterclockwise. So what’s the correct way to move it ?

Ha, now I don't know. I may have moved it the wrong way but it seemed to work better? I have to remove the fan, clutch and shroud tomorrow to send it out for powdercoat. I will play with the spring with a hair dryer on the bench and see what the heck I actually did. Sorry for the confusion.

[RocktimusPryme]

Originally Posted by gto19

Mgarblik

Good info !

If I read your posts correctly you say to move the spring clockwise which would tighten the coil up but when I look at this picture provided in the chevelle link you can see they actually loosened the coil counterclockwise. So what’s the correct way to move it ?

That was kinda my question too. The videos I posted both moved it to the left (CC) as well. But they may have been reverse spinning water pumps?

Im still slightly confused. I might take a picture later and draw on it just to clear up the confusion.

I think I might be afflicted by exactly what you guys are talking about. The fan coming fully on too late. My car sits dead on the 180 thermostat when moving, but climbs some when idling. So I would like to give this mod a shot, but Im still not sure where I should put the outter tang of the spring.

Im a visual person lol. Trying to visualize it in my head Im struggling with.

[RocktimusPryme]

Okay lets look at an illustration to try and clear this up.

So Mick this is how you are saying it should go right? Move the spring to tighten it? And let the outer tang just rest against the side like that.

[gto19]

Originally Posted by RocktimusPryme

Okay lets look at an illustration to try and clear this up.

So Mick this is how you are saying it should go right? Move the spring to tighten it? And let the outer tang just rest against the side like that.

No
Go the other way . You wanna loosen the spring . What he was saying is bend the outer tang clockwise and that will force the coil and center pin counterclockwise. On your fan clutch picture bending the tang really won’t do anything since you don’t have a slot that it rests in .

I provided a picture of my original fan clutch without the modification and a pic of a fan clutch with the modification

[gto19]

Actually looking at yours more close up you probably could bend the tang clockwise and leave it in the hole and it would force the coil counterclockwise

[RocktimusPryme]

Originally Posted by gto19

Actually looking at yours more close up you probably could bend the tang clockwise and leave it in the hole and it would force the coil counterclockwise

Is there room to bend the tang. It doesnt seem like there is much room for error with the 2797 pictured.

That said I think I understand now. Bend the tang to the right which would loosen the spring slightly. Bending the tang right is the same as moving it a slot left.

Could it just be moved out of the slot to the left and rest against the circular knob? Even maybe soldered to the side so it would stay put.

[michaelfind]

Originally Posted by RocktimusPryme

Okay lets look at an illustration to try and clear this up.

So Mick this is how you are saying it should go right? Move the spring to tighten it? And let the outer tang just rest against the side like that.

I realize this is an old question from an old thread and y'all already figured out that the adjustment needs to go counter clockwise. I have been experimenting with my clutch and I think I found what works best for my set up.

I tried moving the tang to the left of the circle but that resulted in the clutch not resetting when cool and basically staying engaged all the time.
I tried to bend a slight tip of the end to stay in the slot but there is not enough material there to make that work.
Also, Super glue did not hold.

I ultimately straightened the end of the spring so that it is held (barely but enough) in the bottom of the original slot but also pushes the coil spring CCW to give me a much cooler temp at idle. I hope this is helpful for others.

[grivera]

Originally Posted by mgarblik

The Hayden tech info recommends the severe duty clutch with fan blades of 2.5" pitch or more. That may be why some people are unhappy with this clutch if they are using a 2" pitch or less fan blade.

How does one measure fan pitch in inches?

[mgarblik]

I measured the pitch of my blade by laying it flat on a table and using a carpenter square to measure the distance from the table to the trailing edge of the blade. (greatest distance from table to blade)