Sending Unit question (68 C20)

[KevinK7]

Short background, my rebuilt quadrajet for the second time now, began dumping fuel all over the intake (infamous stuck float and/or needle). This time I decided to pull the in-carb fuel filter and it was full of 'fibers' and crud.
My initial thought was confirmed as soon as I pulled the sending unit out. the 'sock/filter' was gone, and pieces were in the tank. The (original in-cab) tank itself was amazingly clean.
My truck is an original 68 396 (C20), so it has the 5/16 fuel line and I ordered a replacement sending unit accordingly. I fit right in and line connections were fine.
THEN, I overlooked the wire connection and the photos below show the story.

SO. If anyone has ordered a replacement (5/16 line) sending unit that does have the correct thread/nut wire connection. Where did you source it? (I ordered mine (incorrect connection) through Tamraz).

Also, where are folks sourcing the sock/filter (again, for 5/16" line)?.
My sending unit seemed to work 'OK' so I may opt to just replace the sock if readily available.


Original thread/nut connection:



Replacement 'stud/post' style connection:



Thanks,

Kevin

[pjmoreland]

I ran into the same issue with my 5/16 replacement sending unit from GMCPauls. I replaced the wire with one that had the push-on connector (bought it from member Ironhorse). He has another one listed in the classifieds section right now.

http://67-72chevytrucks.com/vboard/s...d.php?t=824067

Would it be possible to transfer the threaded connection from your old sender to the new sender?

Classic Parts has a 5/16 sock listed on their website. I have no personal experience with this item.

https://www.classicparts.com/1954-87...info/23%2D599/

[Happy_dan]

Or, can you thread the end of that stud so you can put a nut on it?

JEGS Part number 78536 is sock for 5/16th line. Thanks to Mr Mud1, I have one if you need it.

Also, it looks like the post is threaded in, can you just unscrew it and put in the one from the original? (maybe that is what pjmoreland is suggesting)?

Checked the wire he refer to, looks like it is from newer trucks? Maybe able to buy new wire?

[BigBird05]

I should have that wire end if you want to splice it in. it is yours, just pay postage.

[body bolt]

A push nut?

[mr.mud1]

Originally Posted by Happy_dan

Or, can you thread the end of that stud so you can put a nut on it?

JEGS Part number 78536 is sock for 5/16th line. Thanks to Mr Mud1, I have one if you need it.

Also, it looks like the post is threaded in, can you just unscrew it and put in the one from the original? (maybe that is what pjmoreland is suggesting)?

Checked the wire he refer to, looks like it is from newer trucks? Maybe able to buy new wire?

Hi Dan.that fuel sock you have is 3/8's but Jegs did have 5/16's as well.Rock Auto had them listed but one or the other I think is out of stock again?.

[67chevy2wd]

I ran into the same issue. I took the nut off and put the sending unit wire under it just like the old sending unit. Not the right way to do it but it works.

[72c20customcamper]

I did the same been good for 2 years

[KevinK7]

Thanks all for the replies
PM sent to BigBird (Thanks in advance)
I was thinking of putting the wire under the nut that holds the 'post' in place, thanks guys for confirmation that that is an option.

Thanks again,

Kevin

Adding the following for future reference:
Jegs PN 555-78536: (Sending Unit Filter for 5/16 Inlet)
https://www.jegs.com/i/JEGS/555/78536/10002/-1 (Not in stock)

GoldStar PN 189-GT03-641FL
https://www.jegs.com/i/Golden-Star/1...641FL/10002/-1


For those with 3/8 inlet:
Jegs 555-78538 (Sending Unit for 3/8 inlet)
https://www.jegs.com/i/JEGS/555/78538/10002/-1

[KevinK7]

I thought to add the following since I started out with what appeared to be a (quadrajet) carb issue that ends up being a sending unit filter problem.
I started to consider adding an in-line filter, but was hesitant since I really didn't want to cut a new pump to carb fuel line.
As I was reading up on fuel filters, the factory in-carb and often added inline fuel filters it became a bit of an education. I've worked my way around cars all my life, I'm surely no expert, so there's always room to learn

First, on the in-carb filters. I sort of knew this, but never really gave it much attention until now. The original IN-CARB filters actually have a valve in them. Some replacement filters DO have them, some don't. Just for reference, here are pics of an AC Delco with, and another off-brand without:

WITH Valve:


withOUT valve:



Second, I stumbled upon a number of threads/tech articles written by Lars Grimsrud. I don't know him, but he knows his way around quadrajets and his articles are filled with some excellent information. This one especially was very informative.
The text below is noted from Post#10 in this thread:
https://www.corvetteforum.com/forums...-the-carb.html

"
Just a few comments and facts on the subject of fuel filters... most of this has been discussed and debated here on the Forum on a few occasions, and there are some differing opinions. But the following are a few facts on the subject:
GM used in-carb filters on the Q-Jet and on many of the the factory-installed Holley carbs. The in-carb filter actually flows pretty good, and will easily meet the flow demands of a high performance engine. If you're putting out less than 500hp, the in-carb filter is not restricting your performance unless it is defective. Due to its small size, it's a good idea to change the filter at regular intervals to assure free-flowing performance.
Due to the needle/seat assembly in the Q-Jet being placed in the bottom of the float bowl (Holley and AFB carbs have the assemblies in the top of the carb), it is possible for fuel to drain back through the needle/seat after engine shutdown and empty the float bowl. By using an in-carb filter with a checkvalve (NAPA part number 23051 for the pre-'75 short filter and 23052 for the 75+ long filter), you can keep the fuel from draining out of the bowl.
The GM intended purpose of these checkvalve filters was for vehicle roll-over fuel spill protection - it was a safety feature that has some questionable merits, but there was a saftey reason for the in-carb filters...
An in-carb filter allows the use of a one-piece all-metal line between the pump and the carb. Having an all-steel line with no splices on the pressure side of the fuel systemn is a huge safety advantage.
Running 2 filters serves little or no purpose. Run one or the other, but skip the 2-filter idea - it has no merit.
All of the automakers, whether they had in-carb filters or in-line filters, always placed their filters on the pressure side of the pump - never on the suction side. The reason is that the mechanical diaphragm pumps do not "suck" well, and any restriction on the suction side will adversely impact fuel pump performance (both pressure and volume capability). Also, a restriction on the suction side of the fuel system greatly increases the probability of vapor lock on hot days due to the low pressure being applied to the suction line (this causes the hot fuel to vaporize in the line, giving the pump a slug of fuel vapor and terminating its output). Even today, with the advent of high pressure electric pumps for fuel injection systems, the automakers install the filters on the pressure side of the system (the pump is in the tank, and the filter is usually installed someplace along the frame rail between the pump and the engine). Both our old carbureted cars and the new injected cars have a suction side screen: There is a pickup "sock" in the tank to eliminate the big chunks that could hurt the pump, so any additional suction side filter is not required.
If you run a good electric pump back near the tank, you can successfully use a high-flow, high performance filter between the pump and the tank. The good electric pumps are positive displacement vane pumps, and will pull fuel through a filter on the suction side without problem. The stock mechanical pumps do not share this design feature.
Little-known fact: The stock paper and bronze in-carb filters will stop and prevent sugar from entering the carb.... If someone puts sugar in your gas tank, the stock Q-Jet inlet filter will plug up solid from the sugar, but it will not allow the sugar to pass into the carb or into the engine. Most in-line aftermarket filters are screen-type filters, and they will allow the gas/sugar mixt to pass through.
Most people install in-line filters using sections of rubber hose. Rubber hose on the pressure side of a fuel system is simply a bad idea, and countless collector cars have burned to the ground as a result of rubber line on the pressure side of the system. If you elect, for whatever reason, to install an in-line filter, be sure to use all metal line components and screw-on connections. Photo below shows an in-line filter system I built and installed betwen the pump and the carb using all metal connections on a custom engine setup. Such a system is not necessary on a stock engine.
So whichever route you take, keep the filter on the pressure side and do good workmanship to keep your installation safe and reliable. The factory in-carb system is safe and reliable.
Lars"


More notes if you're interested:
https://www.digitalcorvettes.com/thr...by-lars.88376/

https://www.corvetteforum.com/forums...rain-back.html