Joined: Wed Sep 09 2009, 12:28AM
Location: Ft. Collins, Co
Posts: 1
Installing Commander 950/ 700 cfm tbi. on a 64 Dodge 880. I have come to a sending unit issue. I am running my stock tank. I need a return line. My Spectra Premium sending unit has no return line fitting and does not install with out modification, (bottoms out on tank floor). Any advice.
Joined: Wed Dec 21 2005, 07:34AM
Location: indiana
Posts: 791
Moroso (I think) makes a unit that has a nipple on it for a return hose, the item splices into the return tube via hoses and clamps. Search Summitracing.com.
I�m not real wild about this solution as it generally points the return fuel straight into the return pipe, which IMHO would cause lots of splash and subsequent vapor emission. I can�t really argue as I�ve never tried it though.
Be aware, the vent tubes are generally small diameter and the tube then goes to some non-obvious location near teh top of the tank. 4-vent tanks have 4 separate tubes along the top going to 4 corners!
I did some experiments on a junk tank a while back (part of a super-project for Uncle Joe on this site) and I took some pics (65 Dodge 880 tank). Return fittings are fairly straightforward and you have more options if the tank is out of the car. There are a few good locations where a bulkhead fitting can be installed, both in or near the sender and also at the rear of the tank. Whatever location you use, before you drill make sure you can get fingers in there to install the fitting and make sure you can fit a wrench in there to hold/tighten it. Tie a string on the parts so they can be retrieved more easily if you drop them whilst in the tank.
IMHO the return should give the fuel a gentle transition back into the tank � don�t point it directly at a wall, don�t point it at the fuel pickup (return fuel can be aerated), and don�t point it where it will stir up sediment on the bottom of the tank. I believe a fitting at the rear of the tank meets all these guidelines the best.
Installing a bulkhead fitting in the sender is a little trickier than it would seem. I did one of these (sorry, no picture) and there was only a small area where the -6 AN nut would fit without interfering with the inlet tube, the wiring connector, or the tabs that orient the sender in the tank hole. It can be done, though, and a smaller fitting would be easier. I just like AN stuff, that's all!
My EFI system is not running yet (getting closer with each passing week) so the information above (and pictures below) has not been verified by vehicle usage, but it is born of lots of research and planning. However, I did some experiments with the tank and did some water pumping for observation. Was pleased with what I saw.
Feeding a fitting into the tank near the sender...
Fitting installed at the rear near the filler tube...
Fabricated suction tube, would then use the original suction line as a return, which would shoot away from the pickup point (and up the filler neck? )
Both of them together. The oddball rusty tube is an original vent tube.
<span class='smallblacktext'>[ Edited Fri Feb 12 2010, 03:04PM ]</span>
Joined: Mon Dec 22 2008, 07:17PM
Location: Indy
Posts: 5
Holley commander TBI installed on my 1965 Fury. I ran the return line into the filler neck. I put a 90 degree bend at the end of the 5/16 steel tube I welded in so the fuel could run down the filler neck tube without splashing. Fuel mapping now.