Temperature Sender for Edelbrock F4B

VaCat33

VaCat33

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Hello All

I would like to again ask about the the issue in the title above. I know there has been much talk about this recently on the Tiger List but I am still struggling with this.

My gauge reads 40-45 degrees low in comparison to the temperature I got from a laser thermometer (at manifold next to sender). I check the resistance with an ohm meter and it was way too much for the temperature reading accoding to the article on TU...hence the low gauge reading.

I want to change the sender but I have the f4b manifold which I know causes problems.

I am trying to keep this as simple as possible. I have an f4b and there is a sender currently in place. I am just trying to identify and obtain the same sender. I have looked on line and have not seen anything similar, except possibly the replacement sender from Sunbeam Specialties (which would be the easiest solution of all) but that would mean the hole has been rethreaded and since this would have been done by the PO, I am not sure about that (In the paperwork I got from PO one of the receipts does talk about helicoiling the bolt holes on F4b...but not sure if that included the hole for the temp sender.)

I have attached a photo of the sending unit in the manifold. Can anybody make an ID of the sender from the photo alone? Can anybody tell anything else from the photo that might help?

Thanks,

Jim
 
Take it out and head off the Kragen O'Rielly. It may be more common than you think. I'm just gessin'.
That is my scientific brief on the matter.
 
As long as you are going to take it out, you might as well measure its resistance at ambient temperature, out of the manifold, in a nonconductive surface and touched only by ohm meter leads. I have a brand new one for Sunbeam Specialties sitting in its original ziplock package. For what it is worth, the resistance is 505 ohms. If you get near that, my guess is that your problem is elsewhere.

The unit in the picture does look like one from Rick, a Smiths replacement unit, except the one from him that I have has a red insulator top by the terminal instead of a black one. BTW, I also have a used one from another source that is black on the top like yours, again a replacement for the Smiths Sender. It measured 495 ohms.

Cheers, Gene

PS: My ambient air temp is 82 for the measurements I made, should that be relevant...
 
Thanks guys!

I might have spoke too soon. I am embarrassed to say, I tried to get a wrench on the sender and "Man" it is impossible w/o removing several other items...most notably the distributor. I really do not want to do that at this point.

I tried offset wrenches, small wrenches (can't be that small given size of hex), and ratchet. I can not get a wrench on the hex and still clear the distributor.

This job might have to wait...I'll just do the arithmetic for now.

Thanks Again,

Jim
 
Just an idea here from the gallery. You might get enough clearance for a socket by just taking off the distributor cap and not disturbing the distributor and the timing itself. The cap overhangs the top of the distributor body a bit.

BTW, the new sender I have now reads 470 ohms and the garage temp is up to about 89.

It is somewhat interesting that your sender and heater lines are switched from how I have mine installed. I of course am not using the original 90 degree fitting for the heater line like it seems you are. It could be that the hole where the temp gauge is now is a smaller hole than the other one and that it was tapped out for the Smiths sender. If so, you would be in great shape for replacing it without an adapter fitting.

Cheers, Gene
 
Gene

I did some more research online and found the replacement Smiths sender. It liiks almost identical to the one I have currently installed (See photo). Is the Smith's sender the same thread (1/8 NPTF) as the SS replacement sender? If so, I should be good to go.

Thx, Jim
 
Jim, the Smiths sender, and the one Rick sells, both have straight threads instead of pipe threads. However, the threads per inch on the sender are the same as the threads per inch in a hole tapped for a 3/8 inch iron pipe. Thus the sender will screw down in such a hole. But it will be very loose at the top and gradually become tighter as it goes further into the tapered hole.

Unfortunately the threaded portion of the sender is not long enough to really grab enough of the tighter threads at the bottom of the hole for a really good seal for most people's comfort. It looks like you have some sort of sealing washer under your sender in the picture you posted. Once you get it out, you can better see what the PO did and what you have to work with. Were it me, I would just put a new sender, Rick's or other Smiths equivalent, in the same way the old one came out. Remember that you need a good ground connection (sender threads to manifold) so in getting a good coolant seal, don't compromise the grounding aspects.

Cheers, Gene
 
I too just bought an F4B with tapered pipe threads!

Isn't there a part number out there somewhere that belongs to a temp sending unit with (tapered threads) that will work on our tigers? My F4B is the later version with the two elongated holes under the carb, but I'm still reluctant to modify this piece of history. I thought about making a bushing with tapered pipe threads of the next size up and tapping the hole in the manifold to match. The bushing would then have internal straight threads to match the sending unit. Another option I thought of would be to turn the threads off of the sending unit and press fit it into a bushing made with the OE tapered threads. The drawback to this option would be that the sending unit would be a "special", a problem for someone else in the event the unit needs replacing. I don't plan to ever sell the car but I know I will eventually die.:eek:
 
Only Because It Happens !

VaCat33 said:
Gene

I did some more research online and found the replacement Smiths sender. It liiks almost identical to the one I have currently installed (See photo). Is the Smith's sender the same thread (1/8 NPTF) as the SS replacement sender? If so, I should be good to go.

Thx, Jim
Click to expand...

Jim; Clamp a small set of needle-nosed vise grips to the outside of the sender and run a grounding wire from the grips to a known very good ground. There is quite possibly enough pipe dope on the threads to screw up a good grounding thru the F4B. Been there & done that . . . . . .rw
 
You know you're replying to a 1-1/2 year old thread, right? I suspect the OP has resolved his issue by now.
 
Oneoffive has helped me out a few times, so I know he was just being thorough.

Ramseyt used this thread to pose a new but related question just yesterday. So if you have an answer for him please respond.

As for my original problem, the hole on my F4b had been helicoiled by the previous owner, so the sender from SS fit perfectly. Gauge has been providing accurate readings for the past 18 months.:)

Jim
 
There are 3 ways you can do this. 2 are more difficult and 1 is very easy.
1. You can drill out the hole, tap it, and install an insert.
2. You can plug the existing hole then drill another hole in the manifold to the correct size and tap it with the correct threads.
3. You can fill the thread area in the existing pipe thread hole with plenty of RTV, thread the sender in, tighten the sender (but don't put the fear of God in it or you will strip the threads), goop some of the RTV around the base of the sender, and let the RTV dry thoroughly. I have done several of them like this and it works/seals just fine. The one in my car has been in it for 20 years. It doesn't leak, even after a few overheating events :D
 
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