I have installed an electric fan with a temperature sensor on my SBC.
However, I can't use both my mechanical temp gauge & the fan sensor because there is only one fitting on my intake manifold to the water jacket.
How can I do this.

Depending on what cylinder heads you have there may be some plugs in them that you can remove to install the temp sensor. Look for them on the lower part of the cyl heads between and below sparkplugs #'s 1 & 3 and 6 & 8.
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KEEP THE GREAZY SIDE DOWN! Lobucrod

Don't know what engine you are referring to, but on my favorite (small block chev) you can purchase a later model water neck/ thermostat housing with up one or two threaded holes in it. Most reputable countermen can help you page through their heat/air buyer's guide to find what you are looking for. Use the manifold for one and the water neck for the other.

bjb
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There's a world of difference between "good" and "good enough".

Actually, I think that Permacool has a switch and sensor all in one bung mounting that will do both. It may be Derale though........not sure but someone has it. It actually has two electrical male terminals on it. Check it out.

You can also use you temp sensor as is, and an inert sensor which is a mini-tube and it mounts in your radiator fins without penetrating the water jacket. They come in kits with the relay. Derale I know has these as well. Just make sure it is mounted correctly. Those are available from alot of vendors including HAYDEN and work like a charm. I have put alot of them on and will use one for my own project for my wife's 69 Camaro. I use the lowest temperature that you can buy.....I think it's 170*.

I don't recommend sensing off the head....it is a completely different mind set with regard to temperature and where it should live. Head temps come up fast and nome of the devices that use temperature to turn them on are designed for head temps that I know of. The temps run as much as 20 degrees hotter at the head and this may or may not be relative to the whole cooling system. I would rather see temps at the water outlet....tells me more.

Just my 2 cents.

Steve Jack.....Southeastern Goodguys Rep
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SOUTHEASTERN GOODGUYS REP

Thanks GUys.
I found a late model neck with a threaded well for a temperature probe in the Summit catalog.
Will the late model neck fit my Edelbrock early SBC manifold?

I know some foreign cars put the fan sensor in the Rad tank. VW has a sensor with 3 wires that runs the fan at 2 speeds. I know it wont screw into a US car cuz its a big metric thread but maybe someone makes one that will fit. My AFCO rad has a bung in the rad tank for 1/4 NPT pipe thread for one.
The VW fan runs normal at 190' and at 215 goes into hi speed .
Dave

derale makes an adjustable stat. #der-16759 $39.75
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project...39 ford pickup

up through about 1990 (I lost track after that ) all chev waternecks interchange, small block, big block, 6 cyl, most all will fit. I have a cross ram that requires a weird angle for the hose. I'm using a 6 cyl neck.

bjb
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There's a world of difference between "good" and "good enough".

My application is different than most since my engine is in the rear and the radiator is in the front.I used the petcock hole in the radiator for my fan senser.It works very well here.I might add that I relocated my petcock
to the side of the block and it does the same job as it did in the rad....Ray
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Grump

Since my radiator doesn't have a petcock on the bottom tank, I found one that is used in the bottom hose and is made by Moroso. I believe it was in the Speedway and Jeg's catalogs. You cut out about 3+ in. of hose and install the cast aluminum "tube". They come in a couple of sizes also.
Of course if you use this for temp pickup, bear in mind that this is the "cooled" water re-entering the block so the temp will be (hopefuly) cooler. I have a similar tube in the upper hose for filling the system at the highest point and it would not be difficult to drill and tap a pipe thread in it for a temp pickup. So far, that's my plan for my system. Fred P
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Fred P.

Fred.......did I miss something or did you really mean what you said? Putting a 170 degree sensor in the lower hose or lower part of the radiator allows the fan to sit and wait for the already "cooled" water to get to the opening sensed temperature which means that the water entering the radiator at the top will actually be a lot hotter, which could invite hotspots to form faster.??

This sensing point also would be dependent on the ambient temperature of the incoming air as well.

If you are running a temp sensor in the lower part of the radiator I would suggest a 150 degree......but still would be a guess at what the real temperature of the block and heads were.

I sincerely don't recommend that the sensor (either readout or switched) be located at the cold side of the radiator.

Just my 2 cents

Steve Jack......Southeastern Goodguys Rep

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SOUTHEASTERN GOODGUYS REP

Jack; What are your thoughts on running a fan all the time without a temperature switch? R P peggys other half
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Peggy Diegan

Peggy.......as far as I know there are no downsides to doing this other than the system taking longer to heat up and using prolific amounts of amperage. It sure takes away the element of having to worry about the sensor turning your fan on......but it also shortens the life of your fan.

Steve Jack.....Southeastern Goodguys Rep
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SOUTHEASTERN GOODGUYS REP

Thanks Steve; I've been running mine without a sensor and am contemplating put one in. Can't seem to make up my mind as to which one. Yeah, you are right about pulling amperage, especially with the air on and the cd blairing away. On a cruise it will definately tax your battery, especially if you have a good fan. I'm running a spal, and have come close to not starting a couple times. But on a cruise don't know if a switch would help as you will probably be running a fan all the time anyway, if you are not going very fast. Just maybe a larger alternator. Thanks again. R P peggys other half.
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Peggy Diegan

Do yourself a favor and install a two position switch with your sensor/fan switch.Use one side as the auto side and the other side for a manual side just in case your auto fan switch does not work.Just don't do what I did at Lville last year.I thought it would also be nice to use an off position.I accidentally hit the switch to the off position and didn't notice it until it was running anti freeze all over the place.Boy did I have a red face...Ray
PS ain't that right Bryan??
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Grump

Hi Fred; I wondered where that s--- came from that I stepped in while admiring someones ride . Boy that sure is slippery. R P peggys other half
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Peggy Diegan

RP, I prefer to blame that kind of slippery stuff on wearing "blinders".....

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Fred P.

Steve, I don't remember specifying a particular temperture (degrees) to be used in the installation I intend to install. I did however qualify the location temperature differentials but mentioning that the bottom pickup would be cooler and that I was intending to use the upper hose for the pickup. It wouldn't be too big of a stretch to install a temp sensor in both the upper and lower to get an idea as to how efficient your radiator is actually performing. Simply use a spdt switch to monitor either inlet or outlet. Fred P or did I miss the other Fred?
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Fred P.

Fred P........nah.....I'm the one who is cornfused...! Dang memory just doesn't cruise well these days?

Peggy.....it sounded as if you said that during starting that your full time fan was pulling starting power away? If your fan is running when you are cranking the car.....the fan should be on the accessory side of the ignition switch instead of the "hot" ignition side. By wiring all your accessories (radio, air, fan etc) this way, this shuts everything down except for the ignition circuit and the cranking circuit when attempting to start. You might consider a corrective action to save both your battery and a "maybe won't start" situation down the road.

Just a suggestion. Also, to add a sensor to your engine is real easy and you don't have to open the water jacket to do it either. Use one of the Hayden cooler themostat switches that you can buy a Pep Boys....it's an inert little prod that sticks in the radiator just below the inlet and mounts easily there. Take the prod to the non power side of the relay and use a signal voltage to accomplish this. They are available in 165 degrees models. If you need help in wiring this.....email me direct and I will fax you a diagram of how to wire. It's an easy upgrade, but if you have air you will have to bring a signal wire from the compressor lead to run the fan if you want the fan to run continuously when the air is on.

Steve Jack......Southeastern Goodguys REp
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SOUTHEASTERN GOODGUYS REP

Thanks again STeve; Don't usually have a problem starting, it's just when in a slow cruise and thats if it's very long. Do have a funny situation tho , I can idle all day w/air on in 90+ and not overheat, But when doin 80+ ( speed limit in idaho is 75 ) it tends to warm up a bit . I am using a shroud. Generally just ease er back a bit and turn the air off . Have a Weiand intake with two ports ,so if I deciede to put in a sensor will probably go that route. Don't like puttin stuff in the radiator fins. C ya RP peggys other half
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Peggy Diegan

Peggy......which car does this....the bird, the vette or the deuce? I think I already know tho and do you have a carb on it?

90% of the hotter at highway speeds that I have observed (and fixed) are too lean of jets in the primaries. This is esp true when the air needs alot of hp to overcome the drag coef. and leans out even worse under load....or the timing at that RPM could be amiss? There could be some funky airflow issues however that could contribute to the head scratching tho.

Steve Jack....Southeastern Goodguys Rep
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SOUTHEASTERN GOODGUYS REP

It's the 32 roadster, hardly drive the other two any more since the 32 is on the road. It has a 650 edlebrock W/holley twin element air cleaner. You generally have to run quite a few miles before it gets up there. Stay down around 65 and it's just fine. R P peggys other half
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Peggy Diegan

RP.......I have experiences with alot of 32s, and they don't seem to have aero problems (deflections or rolling high pressure zones that would reduce input) with their radiators at high speeeds, and my 32 would cruise all day long at 100 if you could stand it (wind and a low windshield) with out budging off the thermostat. My guess is that either the timing at that rpm is off a little....or my main guess is that you are on the ragged edge of leanville. Have you checked your total timing? Have you done a plug reading at high cruising speed. If not, I do suggest this and even if you have a bit of black soot (sometimes caused by aeromatics in the fuel) the tips should be at least brown or tan....and not white or speckled! If you take the mains (jets) up a notch you may see a better throttle response at speed as well as a cooler gauge. One other possibility is that your water pump is cavitating at whatever the RPMs are at 80ish. I have seen this too. I am assuming that you are using a quality pump tho!

Just my 2 cents FWIW!

Steve Jack...Southeastern Goodguys Rep
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SOUTHEASTERN GOODGUYS REP

Steve; I'll do a plug check ,planned on changing them anyway. Will try the carb increase also. The 21&22 there is a show in twinfalls ,about 200 mile from here would be a good run. It's also peggys birthday ,4/24/? , be a good excuse to take her out. Thanks again RP peggys other half
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Peggy Diegan