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Fuel sending unit

18400 Views 15 Replies 8 Participants Last post by  Toms73NovaSS
I currently have a 427 BBC putting out about 550hp at the flywheel. I would like to go with an electric fuel pump but maintain my stock gas tank. What should I do about the restrictive sending unit? If I put in a sump, it will be noticeable from the rear. Any suggestions? Right now the pump is mechanical but the lines are not very good looking so I am planning a complete fuel system overhaul. I have a single 950 Holley. Thanks all.
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I left my original sending unit in place and cut off the outer part. Then I drilled a hole and put in a 90deg bulkhead fitting and ran 8an line down to make a larger sending tube for my 500 hp BB 454. I have a high volume mechanical pump with press regulator.

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Wow very cool idea, that is definatly what I am going to do. Thanks a lot. Won't get to it for a little while but will let you know how it turns out. Thanks,
Wow, what a cool deal. That is without a doubt the most creative approach I have ever seen to the 40 year old problem with the stock sending units. Whenever we start keeping an archive that will be one of the first things in it. How would you feel about posting that over at

Or, would you mind if I posted a link to this from over there?

If that's a half inch line what is that sock filter from?
Yea why don't you post a link over to this thread, it will serve two purposes, show others my solution and 2 get more people over to this site! Actually that is a stock style filter that I increased the hole diameter to fit over the 1/2 line.

Also on the top bulkhead fitting before I tightened down the nut I placed a small bead of silicon sealer just to make sure that it was a good seal. Worked great last summer!

There is minimal clearance between the trunk floor and the top of the sender unit. There is JUST enough room to sneak the fitting and line that leaves from the fitting in. Make sure you have it pointed in the right direction before you do all of your final tightening.

Here is a pic of it in:

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Do you use a vented or non-vented gas cap with this? Since this setup is only sealed with silicon sealer? I have parts on the way, I hope to have my complete fuel system done by spring!
The silicon sealer is just reassurance for myself. The Jam nut on the bulkhead fitting is what really seals it shut. What also can be done is on the elbow before it is entered thru the hole in the sender top plate is to put an oring. There is a collar where the threads stop and this way the o-ring would be compressed between the elbow and the outer surface of the sender top.

I use a one way vented gas cap, lets air in. (Not like the old 69 previous years that let air in and out) Instead on the ventline in the top I have a rubber stopper and have a very small slit cut in it to let out any pressure that might develop. (You can see it in the tank pic)
Quick Tom and get your patten in!! You'll make millions! By the way I did tell you I'm going to become your patten manager, but don't worry I only take 20%! lol

Actually I hadn't even thought of this problem until I saw the post since my BBC is no where near putting the gas tank or engine in yet! Very good tech tip.
One more question. What type of fuel line are you running to the pump? Braided, aluminum, steel, this is another area where I am going for a clean look, I am staying away from blue and red fittings. Figure chrome, black or grey. Thanks,
A frend and i did this to his camaro, and he didint have any problems when running his mechanical pump but he then put a Holley Black pump and would occasionaly have problems getting a prime out of his Electric fuel pump. If you do use this idea i would suggest keeping a mechanical pump on it.
napsternova said:
One more question. What type of fuel line are you running to the pump? Braided, aluminum, steel, this is another area where I am going for a clean look, I am staying away from blue and red fittings. Figure chrome, black or grey. Thanks,
I used the same aluminum line that you see in the pics with -an fittings. I put a piece of braded between where it transitions between the body and the frame and between the tank and the body. Then finally from the frame to the pump.
That is a very clean mod for sure. Did you reuse the old screen on the pick up? I would put a new one on there. I like the job you did. I might do that to my big block Chevelle. Thanks for the idea and post! :thumbsup:
posted a link in the engines section over on

thanks again for posting that, Tom
sweet, well done.

I would suggest to any readers here that might be considering the use of silicone sealer to be sure to not use the household stuff (that has that vinegar smell) as it is corrosive to metal.

Great pics!
I agree that is a nice setup.

I converted my 69 to EFI and had to go thru something similar but add a larger return line-I removed the OEM vent (which was 1/4 in I believe) and soldered in another 3/8 inch line with similar bends to the OEM 3/8 in-EFI recommendation is two similar sized lines-one for feed and one for return.

I haven't had a problem with the electric pump priming or any other fuel related issues other than possible starvation at low fuel tank levels-mainly due to EFI and lack of a surge box.

There used to be a company that offered new OEM pickups with .5 inch line done...I haven't been able to locate them any more...several years old.

I dislike the 'drag racer' style sump as well...

Have gotten lots of requests for parts used in my conversion:

I used 1/2" alumunum tube flared using 37deg an flare

and (summit part#s)

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