Temp gauge sender best location?

What's the best location for a temp gauge sender in a small block Chevy? I've had some with them in the intake manifold and some with them in the cylinder head. I just put them wherever was more convenient, but always wondered if it made any difference. Which location gives you more useful information and why? Do the cylinder heads read hotter than the intake manifold with the same sender? I've even heard of guys putting a sender in each location and having a switch to check back and forth, but wondered if there's really much of a difference.

Thanks!

 

I stick mine next to the T stat in the intake. I'm sure there is a reason or at least there was the first time I did it that way but its lost to the annuls of time now.

Someone told me once that sticking them in the head wasn't as accurate but I don't know how tru that is.

 

The heads probably will be a little hotter than the rest. I might lean towards putting it in the head because that is what you're most worried about cooling and it will give you a direct read. I usually put mine in the most hidden spot possible. But hey what do I know I'm only a painter.

 

Thanks guys. Yeah, maybe the cylinder head gives you more instantaneous response to give you a little more warning time when things are starting to heat up. But maybe it doesn't matter that much though. I'll probably just put it wherever it looks the least ugly.

 

Lots of theories on this one. ***uming you don't want to use four of them- one on each side of the block & one in each head-- I place it at the back of the block.

My logic is as follows- On a conventional first-gen SBC, & most of the other engines we deal with here, the coolant enters at the front of the block, and travels to the rear of the block (for the most part), cooling the cylider jackets. It then (mostly) goes up into the back of the heads, travels forward, in the process cooling the chambers & valves, & goes by the t-stat to the radiator. Some coolant goes up to the heads without going all the way to the back, but mostly it goes the long way around.

On certain engines, the head gaskets can be accidentally reversed, byp***ing most coolant directly to the front of the heads/intake/t-stat & out. You then typically have a severe overheating condition at the back...but a temp gauge in the t-stat housing may not show it. This is somewhat common on Ford engines that were rebuilt by a non-Ford guy, because when the head gasket is installed correctly it looks wrong. On other engines with corrosion issues you can get the same result. The back location of the gauge gives a more accurate picture, in my view, overall, for a streeter.

Locating the gauge in the head may, or may not, give a better picture. Again, it depends on corrosion in the jackets....and also the type of water pump used. Many SBC pumps, even so-called "good" ones, have a pretty poor balance in water flow from one side to the other. In the block it tends to balance out some, temperature wise, but you will nearly always see markedly higher temps in the weak-side cylinder head....especially at the back. This doesn't in itself mean things are overheating, but it may make you think you're on the ragged edge when in reality the rest of the engine is 20-30 degrees cooler.

Bottom line is, depending on what you are in the mood for, that it pays to experiment. I have seen some circle track cars that used electrical temp gauges (bucking the general trend) in both heads & block....with a switch to select the desired sender.

 

This can be discussed to death. But, I don't think there's enough difference between locations to matter.

 

i'm with groucho, on this one.

 

Ya that sounds about right to me as well.

 

For the most part I would agree with you....or, rather I'd say that in most cases you don't have to worry because you won't have an overheating problem. When you do...

 

Thanks everybody.

Homespun91, when you say "back of the block", what type of engine are you talking about? I don't think a small block Chevy has a tapped hole into the water p***age anywhere near the back of the block, unless I'm forgetting something. There are drains in the center of the sides of the block. I think my only options are the port in the intake near the thermostat housing, the sides of the heads, or the heater ins and outs on the water pump.

It would be nice to have a pretty accurate temperature gauge reading because I'm using a 6" chopped radiator, so I'm probably going to be on the borderline of overheating half the time. I guess the port near the thermostat housing should be sort of an "average" for the whole engine?

Thanks again.

 

Sorry, my bad- I was speaking generally, & I even meant to say "where possible". Some SBC blocks do have a boss on the left (uh, American drivers side- gotta specify, I talk to a fair number of people Down Under ), but many don't. The aftermarket blocks mostly do. It is possible to carefully drill & tap & install a sender, especially in the back side of the head right where the coolant enters from the block....but I don't know if you want to go that far. I tend to get caught up in a lot of racing **** & sometimes get carried away. As Groucho said, probably 95% of the time it doesn't make much difference. If this is a new engine, & you feel comfortable that the engine itself was ***embled right & all crud removed....I'd put it in the intake crossover, on most vehicles, just as you said. If it has a suspect past, or in your case 'cause you have unusual cir***stances with the chopped radiator, I'd use the driver's side cylinder head, because most SBC (& BBC) water pumps flow much less on that side.

If you have tons of liquid cash lying around, & want to spend some $$$ on the cooling system, take a look here: http://www.stewartcomponents.net/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=ChevyHiFlWP Best water pumps on the market, IMHO....or, if those are a trifle spendy, the Weiand Team G pumps come fairly close.

 

Thanks for the good info.

 

The thermostat location is the last point coolant reaches before heading for the radiator and therefore represents the average temp if you will of all the hot and cold spots in the engine. I'd rather know that number for everyday driving. If you are into something like roundtrack compe***ion or other prolonged duration power runs it might help to know where your hot spots are but I am not a racer. My two cents.

 

I know this is a really old thread but I've been searching for information and felt this was the most relevant thread.
Just got back from a 200 mile road trip in my car. I have a big block chevy. New aluminum radiator. I've got two temperature senders. One is in the head and one in the intake manifold. 180 degree thermostat. Ambient temperature yesterday was 90-94 degrees. On the highway, I was running anywhere from 215 to 230 in the cylinder head. The sender in the intake was running 185 to 190 and pretty well just holding steady. Does anyone know what are acceptable temps for the cylinder head? Mine seem a little high but located next to the exhaust... and as hot as it was outside, maybe they're not that far out of line. I was also getting some detonation at the upper end 225-230 range.
Any opinions are welcome on this issue. I was at the frog follies and PRC was there. The opinion there was that 230/235 was nothing to be concerned with at the cylinder head. Seems high to me and when it's affecting the way the motor runs, it's making me question it more. Thanks!