The spot where your gauge sensor is may be the most accurate place. That's where Chrysler chose to put the lean burn temp sensor.

You could try checking a few spots with a hand held infrared temp gauge.

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1976 Feather Duster /6 4sp
1984 W100 318 727 np241
1972 'Cuda 340 4sp
1985 D250 360 46RH

Makes sense to put the FiTech sensor where the factory one is for that reason. I don't suppose anywhere close to that spot would vary much, but I like your scientific approach.

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Yes, factory spot will work. However, I have used the block drain port (already 3/8 NPT) for my MS EFI setups since that warms up more slowly and I feel it follows the engine demand more closely than the head location temperature profile.

Those Chrysler V8 necks will not fit the Slant. The 89-up Chrysler SB V8 has the same t'stat and housing and bolt spacing, but not earlier V8s.

Lou

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Home of Slant6-powered fun machines since 1988

Interesting, is that the drain plug down by the passenger rear side of block or is that an oil galley plug? Pic?

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https://tinyurl.com/yynpj4v2

Yes, coolant drain plug on pass side down and to rear of oil pump.

Lou

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Home of Slant6-powered fun machines since 1988

Thanks Lou, I'm traveling or I'd look on my block. I recall DD showing an oil gallery plug down there too, on '68 and later blocks I think he said. Not sure what year mine is, never checked the number.

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https://tinyurl.com/yynpj4v2

FiTech guys say it can't be placed after the thermostat, and the sensor has to be in the intake manifold (V8 applications), and so what you're suggesting sounds interesting, Lou. It seems like it would be less hot there (on the V8) but it's still before the thermostat. It would be interesting to take temp readings at the drain plug site on a SL6 vs intake spot on a v8. Might have similar heat cycles. Does seem intuitive the the stock temp sensor site would be hotter or at least more consistently hot though.


Brian

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https://tinyurl.com/yynpj4v2

YMMV...

The Slant intake is not heated in aftermarket apps, and is heated differently than in V8s. A temp sensor in a Slant intake location would read drastically differently than at the head location. I believe you want the warm-up curve to match the intake tract warm-up curve and the cylinder wall and piston warm-up curve. The front/top of the head will heat up faster than both of those.

I am not saying that can't work, but I felt it did not work as well as the block location. The head location shows you the hottest point, and so that is the point you want to monitor for SAFETY against overheating. I do not see that should necessarily be the right point for monitoring for EFI warm-up.

Lou

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Home of Slant6-powered fun machines since 1988

Lou,

That is interesting data, and I'm not just saying that because it might save me from drilling and tapping any holes .

There was an earlier comment on later chrysler's having a special (emmissions?) sensor in that head position; I assume the "hottest" nature of that spot must be appropriate for that sensor type (or perhaps it was just too inconvenient for them to put it elsewhere?).

Here is a pic of my block drain plug (and the oil gallery one to the left). https://tinyurl.com/y8o5xo3v

So, if you are correct about the drain plug spot being more in tune with what a FI system needs, then I might install it there and leave the current temp sensor where it is, see: https://tinyurl.com/y7ggean9 I did get your YMMV message, but it's worth a try there. After all, it is "before the thermostat" in the coolant flow path like FiTech recommends, just way before, but still not like fresh out of the bottom radiator hose. It is near the rear of the block, but not close to the head. I'll get her warmed up and take a few temp readings there vs at the head spot, just to compare. Anyone done that?

BTW, I figured out the apparent visual discrepancy in the picture in the first post I referred to and my head, it is that my valve cover extends way over the sealing surface on the head and so there's not as much room in that flat area on top of the head near the thermostat housing for the 3/8 NPT hole there on my head unless I use e.g. the tin valve cover or drill closer to the thermostat housing (and not have that full 1/2" of space referred to between the thermostat copper plug and the new sensor).

Interesting stuff.

Brian

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https://tinyurl.com/yynpj4v2

Can't hurt to try. I would drill/tap out your stock sensor hole to 3/8 NPT before you put the head on (if it's off). Then, use an adapter to put in the stock T sensor and you can remove that later if you want to switch. You also can do it on the car if you use grease on the bit and tap, and vacuum out the head behind the tstat hole.

I always drill/tap mine out these days anyway, in case I want to use a larger aftermarket T sensor on an engine.

Lou

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Home of Slant6-powered fun machines since 1988

The head is on, but good point, if I'm going to drain the block anyway, I might as well do the head to 3/8 NPT while it's drained.

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https://tinyurl.com/yynpj4v2

I drained the system. FYI, for those who have never done this, draining the radiator at the petcock is merely the first step. After that, when removing the drain plug on the side of the block, you get nearly 3/4 gallon more coolant. Since I'm running Evans waterless and it's expensive, I taped a piece of plastic wrap to the block just under the plug and put a container below that. When I removed the plug, the coolant ran down the plastic sheet and into my container quite nicely. https://tinyurl.com/ycn7kcxl Didn't lose a drop, and nothing touched the (new) paint. The drain plug came out easily, was not rusted in place. It had what looked like the original paint on the threads.

I ended up putting the factory temp sender (I actually used a Ford model with 3/8 NPT threads) in the drain plug hole on the side of the block, and put the FiTech temp sensor in the hole on the head (after drilling/tapping to 3/8 NPT). https://tinyurl.com/y9bvax4u

I took some temperature measurements before deciding on this, and my intake runner temperature curves seemed to match that of the temp sensor spot in the head more than the one in the side of the block. This could be because I ceramic coated my exhaust manifolds in black - the most emissive color, radiates more heat than say, silver or grey. Also, I have a carb heat shield that reflects all that emitted heat back to the intake runners. Anyway, the temp sensor in the drain plug hole works fine for the factory temp gauge.

Note, I did not remove the thermostat housing to do this work. Since I expanded the hole in the head where the factory temp sensor was, from 1/8 NPT to 3/8 NPT, I found that my mini-vacuum attachments actually fit in the 3/8 NPT hole. I removed the metal shavings with vacuum as I drilled the hole, and after I tapped the hole I put the vacuum into the head and sucked out the metal shavings that fell into the head (apparently) cleanly. The amount of material that I collected must surely have accounted for >95% of that created during the drilling/tapping.

Next step is pulling the intake/exhaust manifolds/carbs, installing the Fitech system, wiring it up and going from there. FYI, I fabricated the linkage for Lokar cables, nothing OEM fits the FiTech system. It's not pretty, but it is very solid.

https://tinyurl.com/ycdwzth6\

https://tinyurl.com/yayph59s

https://tinyurl.com/yd7yx2jl

Brian

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I had a dual pulley on my alternator, I had to cut off the outer pulley to make enough room for the FiTech fuel command center to fit down next to the radiator on the passenger side. This is where I used to have my 4" hole/duct for my cold air intake. I had to remove that, but now there is a hole there that will cool the fuel command center. I had to weld up a bracket to mount the fuel command center bracket. https://tinyurl.com/yc3675ux I had to move the horn on that side (I have two), will have to figure out where to put it.

FYI, a pic of the offy 4bbl intake after painting. https://tinyurl.com/y7qmr85w

b

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Are you going to document the FiTech install on this thread or start a new thread on it? I definitely want to follow along since I also have a basic FiTech unit but am no where near any kind of installation.

You might be aware of it but a lot of people on the FABO as well as on a Facebook FiTech forum I'm on have had to replace their temperature sensors because the FiTech sensor was calibrated about 20 degrees too low leading to drive ability issues.

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65 Dart station wagon slant 6 - now under construction
47 Dodge Custom 4 Door sedan
87 D100 Short Bed slant 6

Retired USAF 1966-1986
Retired US Postal Service 2004-2014

Hi, thank you. Sure, I will document in a new thread.

Can you tell me more about or point me toward the issue thread with the temp sensor? This is an AC Delco sensor they include with the kit, part number 15326386.

Brian

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