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[GMCnet] Fan clutch and air flow [message #95549] Thu, 12 August 2010 13:23 Go to next message
Gerald Work is currently offline  Gerald Work   United States
Messages: 102
Registered: June 2010
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Senior Member
We are in a lot of extreme heat and humidity passing east to west through thE midwest. We have an aluminum radiator, no finder liners, 3.5 gearing, not towing and the coach weighs just at 12,400 with both of us and our stuff in along with full water, holding and fuel tanks. Once the outside temp passes 95 degrees the fan clutch cycles about every 15 to 20 minutes even though water temp never exceeds 200 degrees on my vdo gauge. It comes on very predictably when slowing from 65 to around 55.

Not objectionable, just how this one works.

Jerry Work
Kerby, OR
78 Royale with 455

Sent from my iPad
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Re: [GMCnet] Fan clutch and air flow [message #95560 is a reply to message #95549] Thu, 12 August 2010 15:27 Go to previous messageGo to next message
Ray Erspamer is currently offline  Ray Erspamer   United States
Messages: 1707
Registered: May 2007
Location: Milwaukee Wisconsin
Karma: -3
Senior Member
Do you know which model fan clutch you have Jerry.....that's the way my original
one worked and I want to get back to it, but I don't know what was in there.

Ray


Ray & Lisa Erspamer
78 Royale Center Kitchen
TZE368V101144
Wauwatosa, Wisconsin 53226
Email: 78GMC-Royale@att.net
414-745-3188
Web Site: http://ray-lisa.page.tl/




________________________________
From: Gerald Work <glwork@me.com>
To: gmclist@temp.gmcnet.org
Sent: Thu, August 12, 2010 1:23:09 PM
Subject: [GMCnet] Fan clutch and air flow

We are in a lot of extreme heat and humidity passing east to west through thE
midwest. We have an aluminum radiator, no finder liners, 3.5 gearing, not
towing and the coach weighs just at 12,400 with both of us and our stuff in
along with full water, holding and fuel tanks. Once the outside temp passes 95
degrees the fan clutch cycles about every 15 to 20 minutes even though water
temp never exceeds 200 degrees on my vdo gauge. It comes on very predictably
when slowing from 65 to around 55.


Not objectionable, just how this one works.

Jerry Work
Kerby, OR
78 Royale with 455

Sent from my iPad
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Ray Erspamer 78 GMC Royale Center Kitchen 403, 3.70 Final Drive Holley Sniper Quadrajet EFI System, Holley Hyperspark Ignition System 414-484-9431
Re: [GMCnet] Fan clutch and air flow [message #95568 is a reply to message #95549] Thu, 12 August 2010 16:42 Go to previous messageGo to next message
Bob de Kruyff   United States
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
Senior Member
Gerald Work wrote on Thu, 12 August 2010 12:23

We are in a lot of extreme heat and humidity passing east to west through thE midwest. We have an aluminum radiator, no finder liners, 3.5 gearing, not towing and the coach weighs just at 12,400 with both of us and our stuff in along with full water, holding and fuel tanks. Once the outside temp passes 95 degrees the fan clutch cycles about every 15 to 20 minutes even though water temp never exceeds 200 degrees on my vdo gauge. It comes on very predictably when slowing from 65 to around 55.

Not objectionable, just how this one works.

Jerry Work
Kerby, OR
78 Royale with 455

Sent from my iPad
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That sounds just about as good as it gets!!


Bob de Kruyff
78 Eleganza
Chandler, AZ
Re: [GMCnet] Fan clutch and air flow [message #95608 is a reply to message #95549] Thu, 12 August 2010 21:26 Go to previous messageGo to next message
shawnee is currently offline  shawnee   United States
Messages: 422
Registered: February 2004
Location: NC
Karma: 0
Senior Member
[quote title=Gerald Work wrote on Thu, 12 August 2010 14:23]We are in a lot of extreme heat and humidity passing east to west through thE midwest. We have an aluminum radiator, no finder liners, 3.5 gearing, not towing and the coach weighs just at 12,400 with both of us and our stuff in along with full water, holding and fuel tanks. Once the outside temp passes 95 degrees the fan clutch cycles about every 15 to 20 minutes even though water temp never exceeds 200 degrees on my vdo gauge. It comes on very predictably when slowing from 65 to around 55.

Not objectionable, just how this one works.

Jerry Work
Kerby, OR
78 Royale with 455

Sent from my iPad]

Jerry,

My Delco 4644 started doing the same as your fan clutch. One thing to remember is that you cannot expect a direct correlation between the fan clutch and engine temperature. The heat coming to the fan clutch is a result of the ambient air temperature,
the heat generated by the air conditioner, and the coolant heat going through the radiator. The engine temperature is the result of heat generated by gasoline in the cylinders.

I changed to a Hayden 2797 and had worse results with temperature going to 200 degrees in stop and go traffic and 205+ degrees going up small hills and never hearing the fan clutch. My gurus, Bob de Kruff and Steve Ferguson had better results although Bob had to replace his first one with a second one before he got good results. I also replaced the first Hayden with another today and my temperatures are now normal and I can hear the fan clutch come on now. I understand people in the western states are having the same problem with the fan clutch coming on frequently and it appears the temperature control was changed to about 10 degrees less to turn on the clutch. On very hot days this can make the clutch come on often and be very irritating as well as lower gas mileage. The exceptional hot weather we are having all over the country isn't helping this problem.


Gene Dotson
74 Canyonlands
www.bdub.net/Motorhome_Enhancements New Windows and Aluminum Radiators
Re: [GMCnet] Fan clutch and air flow [message #95611 is a reply to message #95608] Thu, 12 August 2010 21:44 Go to previous messageGo to next message
C Boyd is currently offline  C Boyd   United States
Messages: 2629
Registered: April 2006
Karma: 18
Senior Member

Jerry,

My Delco 4644 started doing the same as your fan clutch. One thing to remember is that you cannot expect a direct correlation between the fan clutch and engine temperature. The heat coming to the fan clutch is a result of the ambient air temperature,
the heat generated by the air conditioner, and the coolant heat going through the radiator. The engine temperature is the result of heat generated by gasoline in the cylinders.

I changed to a Hayden 2797 and had worse results with temperature going to 200 degrees in stop and go traffic and 205+ degrees going up small hills and never hearing the fan clutch. My gurus, Bob de Kruff and Steve Ferguson had better results although Bob had to replace his first one with a second one before he got good results. I also replaced the first Hayden with another today and my temperatures are now normal and I can hear the fan clutch come on now. I understand people in the western states are having the same problem with the fan clutch coming on frequently and it appears the temperature control was changed to about 10 degrees less to turn on the clutch. On very hot days this can make the clutch come on often and be very irritating as well as lower gas mileage. The exceptional hot weather we are having all over the country isn't helping this problem.[/quote]








Hi Gene: could you hear the fan you just replaced on start up?? compared to the one you just put on??


C. Boyd
76 Crestmont
East Tennessee
Re: [GMCnet] Fan clutch and air flow [message #95636 is a reply to message #95549] Fri, 13 August 2010 00:53 Go to previous messageGo to next message
George Beckman is currently offline  George Beckman   United States
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Registered: October 2008
Location: Colfax, CA
Karma: 11
Senior Member
Gerald Work wrote on Thu, 12 August 2010 11:23

We are in a lot of extreme heat and humidity passing east to west through thE midwest. Once the outside temp passes 95 degrees the fan clutch cycles about every 15 to 20 minutes even though water temp never exceeds 200 degrees on my vdo gauge. It comes on very predictably when slowing from 65 to around 55.

Not objectionable, just how this one works.

Jerry Work
Kerby, OR
78 Royale with 455




I have had two coaches. One is a Hayden and I have no idea what is on the current coach. However, I have watched the engine water temperature and listened to fan clutches go in an out. I "believe" I have seen the clutch go on when the engine temperature was (or by the gauge, appeared to be) lower than the usual cut in point.

In my mind, I have placed the cause of this on the condenser for the dash air. The fan is activated by the bi-metal spring on the front. Is it not possible that sometimes it comes on because of the hot air added by the air conditioner? I do know that the air conditioner causes the radiator to have to work harder, but I am referring to the times when the temp is still at 195 (with a clutch that comes on at 200) and the fan comes on.


'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
Re: [GMCnet] Fan clutch and air flow [message #95660 is a reply to message #95611] Fri, 13 August 2010 08:20 Go to previous messageGo to next message
shawnee is currently offline  shawnee   United States
Messages: 422
Registered: February 2004
Location: NC
Karma: 0
Senior Member
C Boyd wrote on Thu, 12 August 2010 22:44


Jerry,

My Delco 4644 started doing the same as your fan clutch. One thing to remember is that you cannot expect a direct correlation between the fan clutch and engine temperature. The heat coming to the fan clutch is a result of the ambient air temperature,
the heat generated by the air conditioner, and the coolant heat going through the radiator. The engine temperature is the result of heat generated by gasoline in the cylinders.

I changed to a Hayden 2797 and had worse results with temperature going to 200 degrees in stop and go traffic and 205+ degrees going up small hills and never hearing the fan clutch. My gurus, Bob de Kruff and Steve Ferguson had better results although Bob had to replace his first one with a second one before he got good results. I also replaced the first Hayden with another today and my temperatures are now normal and I can hear the fan clutch come on now. I understand people in the western states are having the same problem with the fan clutch coming on frequently and it appears the temperature control was changed to about 10 degrees less to turn on the clutch. On very hot days this can make the clutch come on often and be very irritating as well as lower gas mileage. The exceptional hot weather we are having all over the country isn't helping this problem.









Hi Gene: could you hear the fan you just replaced on start up?? compared to the one you just put on?? [/quote]

Chuck,

I was surprised, but the 2797 sounded just like the 4644 when it activated. I hesitated to use a Hayden since my experience with them has not been good. As I mentioned, I had to get a second one since the first one did not work. I think if you buy one you should get it locally where you can exchange it it if the first one doesn't work. Now I have to see how long it lasts. Hope you are going to DeQuoin next month.


Gene Dotson
74 Canyonlands
www.bdub.net/Motorhome_Enhancements New Windows and Aluminum Radiators
Re: [GMCnet] Fan clutch and air flow [message #95668 is a reply to message #95660] Fri, 13 August 2010 09:31 Go to previous messageGo to next message
C Boyd is currently offline  C Boyd   United States
Messages: 2629
Registered: April 2006
Karma: 18
Senior Member
shawnee wrote on Fri, 13 August 2010 09:20

C Boyd wrote on Thu, 12 August 2010 22:44


Jerry,

My Delco 4644 started doing the same as your fan clutch. One thing to remember is that you cannot expect a direct correlation between the fan clutch and engine temperature. The heat coming to the fan clutch is a result of the ambient air temperature,
the heat generated by the air conditioner, and the coolant heat going through the radiator. The engine temperature is the result of heat generated by gasoline in the cylinders.

I changed to a Hayden 2797 and had worse results with temperature going to 200 degrees in stop and go traffic and 205+ degrees going up small hills and never hearing the fan clutch. My gurus, Bob de Kruff and Steve Ferguson had better results although Bob had to replace his first one with a second one before he got good results. I also replaced the first Hayden with another today and my temperatures are now normal and I can hear the fan clutch come on now. I understand people in the western states are having the same problem with the fan clutch coming on frequently and it appears the temperature control was changed to about 10 degrees less to turn on the clutch. On very hot days this can make the clutch come on often and be very irritating as well as lower gas mileage. The exceptional hot weather we are having all over the country isn't helping this problem.









Hi Gene: could you hear the fan you just replaced on start up?? compared to the one you just put on??


Chuck,

I was surprised, but the 2797 sounded just like the 4644 when it activated. I hesitated to use a Hayden since my experience with them has not been good. As I mentioned, I had to get a second one since the first one did not work. I think if you buy one you should get it locally where you can exchange it it if the first one doesn't work. Now I have to see how long it lasts. Hope you are going to DeQuoin next month.[/quote]







Thanks Gene.. I had always thought that if you could hear the fan on start up it was good. Another one of my misconscrewed assumptions.
We do have reservations sent in for DuQuoin and early arrival for GMCES but have not received confirmation. Maybe we don`t get one? If I can get my offset bushings, aligment, transfer switch, and intake gaskets done and the good Lord is willing.....


C. Boyd
76 Crestmont
East Tennessee
Re: [GMCnet] Fan clutch and air flow [message #95683 is a reply to message #95549] Fri, 13 August 2010 11:48 Go to previous messageGo to next message
Gary Casey is currently offline  Gary Casey   United States
Messages: 448
Registered: September 2009
Karma: 0
Senior Member
I'm not sure I understand the controversy about fan clutches. As written below,
the clutch engages as a function of the air temperature behind the radiator, not
the engine coolant temp. One way to look at it: The hot tank (left side) will
be at engine block temperature always. The thermostat will be partially open
and there isn't anything to cool the hot tank. The radiator tubes will start
out hot on the left side and then cool as you go from left to right. The right
tank will be cool. The air temperature downstream will therefore be relatively
low. As the engine is asked to put out more power, the heat output will go up
and the thermostat will open further. Consequently, more of the radiator will
be hot (the transition from hot to cool, while not sharp, can be envisioned to
move from left to right). Finally, with the thermostat full open, the engine
will come "off the thermostat" and the temperature will start to rise. With all
the radiator tubes "hot" the air temperature will also be hot and the fan will
come on at some point.

But why try to get the fan to turn on before the engine comes off the
thermostat? It just sucks up horsepower for no benefit. I would like to see
the engine temperature start to rise and at some point between that and
overheating have the fan turn on. Whether this is at 205 coolant or 225 doesn't
make much difference. The engine certainly doesn't care if it runs at 180 or
220. Although, I'll admit it is more likely to "percolate" if it is shut off
when at the higher temperatures.
Gary Casey
'73 23 with a fan that never turns on (yeah, I should replace it)

C Boyd wrote on Thu, 12 August 2010 22:44
> Jerry,
>
> My Delco 4644 started doing the same as your fan clutch. One thing to
>remember is that you cannot expect a direct correlation between the fan clutch
>and engine temperature. The heat coming to the fan clutch is a result of the
>ambient air temperature,
> the heat generated by the air conditioner, and the coolant heat going through
>the radiator. The engine temperature is the result of heat generated by
>gasoline in the cylinders.
>
> I changed to a Hayden 2797 and had worse results with temperature going to 200
>degrees in stop and go traffic and 205+ degrees going up small hills and never
>hearing the fan clutch. My gurus, Bob de Kruff and Steve Ferguson had better
>results although Bob had to replace his first one with a second one before he
>got good results. I also replaced the first Hayden with another today and my
>temperatures are now normal and I can hear the fan clutch come on now. I
>understand people in the western states are having the same problem with the fan
>clutch coming on frequently and it appears the temperature control was changed
>to about 10 degrees less to turn on the clutch. On very hot days this can make
>the clutch come on often and be very irritating as well as lower gas mileage.
>The exceptional hot weather we are having all over the country isn't helping
>this problem.



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Re: [GMCnet] Fan clutch and air flow [message #95696 is a reply to message #95683] Fri, 13 August 2010 13:25 Go to previous messageGo to next message
Bob de Kruyff   United States
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
Senior Member
""But why try to get the fan to turn on before the engine comes off the
thermostat? It just sucks up horsepower for no benefit. I would like to see
the engine temperature start to rise and at some point between that and
overheating have the fan turn on. Whether this is at 205 coolant or 225 doesn't
make much difference. The engine certainly doesn't care if it runs at 180 or
220. Although, I'll admit it is more likely to "percolate" if it is shut off
when at the higher temperatures.
Gary Casey
'73 23 with a fan that never turns on (yeah, I should replace it)
"


I don't sense any controversy just an interesting exchange of conditions and thoughts. Although this is becoming a very large thread, I think we have some interesting thoughts coming out of it. I guess I haven't noticed any desire to have the clutch come on before the thermostat is open. Personally I think it does make a difference if the engine runs at 185 vs 220. I consider 220 as way too hot for my coach. Elevated temperatures result in increased oil consumption, accelerated degradation of the engine oil, increased transmission temperature, increased hot soak temperatures and so on. Just my opinion I suppose.


Bob de Kruyff
78 Eleganza
Chandler, AZ
Re: [GMCnet] Fan clutch and air flow [message #95718 is a reply to message #95696] Fri, 13 August 2010 18:01 Go to previous messageGo to next message
Ken Henderson is currently offline  Ken Henderson   United States
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
Senior Member
Talk, talk, talk.

Let's DO something!

http://www.gmcmhphotos.com/photos/showgallery.php?cat=5567
<http://www.gmcmhphotos.com/photos/showgallery.php?cat=5567>
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI+ & EBL
www.gmcwipersetc.com



On Fri, Aug 13, 2010 at 2:25 PM, Bob de Kruyff <NEXT2POOL@aol.com> wrote:

>
>
> ""But why try to get the fan to turn on before the engine comes off the
> thermostat?...
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
Re: [GMCnet] Fan clutch and air flow [message #95722 is a reply to message #95549] Fri, 13 August 2010 18:29 Go to previous messageGo to next message
g.winger is currently offline  g.winger   United States
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Registered: February 2008
Location: Warrenton,Missouri
Karma: 0
Senior Member
Ken, thats so cool!! Now all you need is to borrow a glass engine cover. Bet there might be one at duquoin in late sept.!!
Re: [GMCnet] Fan clutch and air flow [message #95724 is a reply to message #95722] Fri, 13 August 2010 18:42 Go to previous messageGo to next message
Ken Henderson is currently offline  Ken Henderson   United States
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
Senior Member
HEY! That's the way to see what they do! :-)

I may even have a piece of Lexan big enough to do it before then. Certainly
got enough to embed in a temporary plywood hatch.

A TV camera might be easier.

Ken H.



On Fri, Aug 13, 2010 at 7:29 PM, Paul Leavitt <leavittpaul@yahoo.com> wrote:

>
>
> Ken, thats so cool!! Now all you need is to borrow a glass engine cover.
> Bet there might be one at duquoin in late sept.!!
> _______________________________________________
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
Re: [GMCnet] Fan clutch and air flow [message #95728 is a reply to message #95718] Fri, 13 August 2010 19:03 Go to previous messageGo to next message
wally is currently offline  wally   United States
Messages: 643
Registered: August 2004
Location: Omaha Nebraska
Karma: 5
Senior Member
Ken Henderson wrote on Fri, 13 August 2010 18:01

Talk, talk, talk.

Let's DO something!

http://www.gmcmhphotos.com/photos/showgallery.php?cat=5567
<http://www.gmcmhphotos.com/photos/showgallery.php?cat=5567>
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI+ & EBL
www.gmcwipersetc.com




I'm real interested in the flaps effect. You took the bull by the horns. Thanks


Wally Anderson
Omaha NE
75 Glenbrook
Re: [GMCnet] Fan clutch and air flow [message #95731 is a reply to message #95728] Fri, 13 August 2010 19:20 Go to previous messageGo to next message
Ken Henderson is currently offline  Ken Henderson   United States
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
Senior Member
The problem now is that I don't really have a base line to determine the
effects of the flaps. The Cad500 was running hotter than I expected before
this change. But, if it runs cooler when I put it back on the road, I won't
really know why: I suspect I was running with inadequate spark advance
which will be corrected. And, I'm correcting too little preload on the
lifters, which could have affected engine heat production.

I guess what I'll do is run with the flaps operating until I can establish a
base line for the new engine configuration. Then I'll lock the flaps closed
and compare the results. Which means I need to consider how to easily lock
them before I reinstall the shroud. Gorilla Tape may be the way. :-)

This could be a longer term project than expected, but I'll try to gather
some significant data during the trip to Du Quoin & back.

Tomorrow, after I find springs for the side doors, I expect to test their
operation with a BIG squirrel cage blower.

Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI+ & EBL
www.gmcwipersetc.com


On Fri, Aug 13, 2010 at 8:03 PM, Wally Anderson <wallyand@aim.com> wrote:

>
>
> Ken Henderson wrote on Fri, 13 August 2010 18:01
> > Talk, talk, talk.
> >
> > Let's DO something!
> >
> > http://www.gmcmhphotos.com/photos/showgallery.php?cat=5567
> > <http://www.gmcmhphotos.com/photos/showgallery.php?cat=5567>
> > Ken H.
> > Americus, GA
> > '76 X-Birchaven w/Cad500/Howell EFI+ & EBL
> > www.gmcwipersetc.com
>
> I'm real interested in the flaps effect. You took the bull by the horns.
> Thanks
> --
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
Re: [GMCnet] Fan clutch and air flow [message #95734 is a reply to message #95718] Fri, 13 August 2010 19:37 Go to previous messageGo to next message
Bob de Kruyff   United States
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
Senior Member
""Talk, talk, talk.

Let's DO something!
""

I knew sooner or later you would volunteer. Which initiative do you want to start with?


Bob de Kruyff
78 Eleganza
Chandler, AZ
Re: [GMCnet] Fan clutch and air flow [message #95735 is a reply to message #95718] Fri, 13 August 2010 19:41 Go to previous messageGo to next message
Bob de Kruyff   United States
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
Senior Member
Ken--what problem are you trying to fix? Do other 500 conversions have problems?

Bob de Kruyff
78 Eleganza
Chandler, AZ
Re: [GMCnet] Fan clutch and air flow [message #95739 is a reply to message #95718] Fri, 13 August 2010 19:50 Go to previous messageGo to next message
Steven Ferguson is currently offline  Steven Ferguson   United States
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Registered: May 2006
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Senior Member
It's about time you got off your butt and did something Ken :>)
I think a lot of us that are having fan clutch diffigulties have the
full shrouds. Maybe there was a reason why GM engineers left a large
portion of the L side unshrouded. Your flap gizmos might just do the
trick. I think I'd start with one though. Those are pretty big
flaps.

On Fri, Aug 13, 2010 at 4:01 PM, Ken Henderson <hend4800@bellsouth.net> wrote:
> Talk, talk, talk.
>
> Let's DO something!
>
> http://www.gmcmhphotos.com/photos/showgallery.php?cat=5567
>  <http://www.gmcmhphotos.com/photos/showgallery.php?cat=5567>
> Ken H.
> Americus, GA
> '76 X-Birchaven w/Cad500/Howell EFI+ & EBL
> www.gmcwipersetc.com
>
>
>
> On Fri, Aug 13, 2010 at 2:25 PM, Bob de Kruyff <NEXT2POOL@aol.com> wrote:
>
>>
>>
>> ""But why try to get the fan to turn on before the engine comes off the
>> thermostat?...
>>
> _______________________________________________
> GMCnet mailing list
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>



--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/
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Re: [GMCnet] Fan clutch and air flow [message #95743 is a reply to message #95735] Fri, 13 August 2010 20:00 Go to previous messageGo to next message
Ken Henderson is currently offline  Ken Henderson   United States
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
Senior Member
Bob,

When I assembled the 500, I somehow built an oil leak into the cam chain
cover. That's why I had the lower half of the shroud, and the fan & clutch
off already. With only two captive bolts holding the top half on, I could
hardly beg off from adding the flaps Rick's been wanting. (Can't let the
young whippersnapper get ahead of me!)

Since 500's are known to run hotter than 455's, I figure I can stand any
help the flaps may provide. But some things I've recently learned about EFI
and computer controlled distributors make me think I've been running
insufficient spark advance, making mine run even hotter.

As for 500 conversions having problems, no, I don't think so. But I have
learned in the past couple of days that I'm not the only ancient amateur
who's failed to consider the lifter pre-load spec carefully enough. I
completely forgot to check it until I had the engine almost in its home. Of
course, with a reground cam, the pre-load was out of spec. With the longer
push rods I got today, that should be fixed tomorrow.

Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI+ & EBL
www.gmcwipersetc.com



On Fri, Aug 13, 2010 at 8:41 PM, Bob de Kruyff <NEXT2POOL@aol.com> wrote:

>
>
> Ken--what problem are you trying to fix? Do other 500 conversions have
> problems?
> --
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
Re: [GMCnet] Fan clutch and air flow [message #95746 is a reply to message #95739] Fri, 13 August 2010 20:08 Go to previous messageGo to previous message
Ken Henderson is currently offline  Ken Henderson   United States
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
Senior Member
Yeah, I know, it's awfully hard to stay under the coach instead of in the
pool when it's 95*F+ outside. :-)

I suspect you're right about the full shrouds. That open area ahead of the
driver, right where the coolant's hottest, could make up for an awful lot of
idling fan flow resistance.

I'm surprised you think the vents are big -- I was trying to figure how to
make them bigger. :-)

It will be a whole lots easier to keep them closed than it would have been
to add more, I'll probably go ahead and drill them for locking screws and
just use Gorilla tape for any temporary test locking.

Ken H.


On Fri, Aug 13, 2010 at 8:50 PM, Steven Ferguson <botiemad11@gmail.com>wrote:

> It's about time you got off your butt and did something Ken :>)
> I think a lot of us that are having fan clutch diffigulties have the
> full shrouds. Maybe there was a reason why GM engineers left a large
> portion of the L side unshrouded. Your flap gizmos might just do the
> trick. I think I'd start with one though. Those are pretty big
> flaps.
>
> On Fri, Aug 13, 2010 at 4:01 PM, Ken Henderson <hend4800@bellsouth.net>
> wrote:
> > Talk, talk, talk.
> >
> > Let's DO something!
> >
> > http://www.gmcmhphotos.com/photos/showgallery.php?cat=5567
> > <http://www.gmcmhphotos.com/photos/showgallery.php?cat=5567>
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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