New Carb, has no fuel return line hookup?

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agarair

New Carb, has no fuel return line hookup?

Post by agarair »

Finally got tired of driving around on one 28mm barrel as the secondary hasn't opened up in a year. Replacing the original carb on a 71 1608cc with a Weber DFEV and installing an 1800 intake manifold. Anyone know what I do about the fuel return line? New Weber doesn't have a fuel return provision for sending fuel back to the tank like the original.Will this cause any problem for the original mechanical fuel pump?

Thoughts/recommendations appreciated. Toby sends.
BEEK
Posts: 1833
Joined: Wed Mar 24, 2010 10:45 pm
Your car is a: 1975 Spider
Location: clermont fl

Re: New Carb, has no fuel return line hookup?

Post by BEEK »

should pose no problems, just plug the return line going back to your tank. this is assuming that you are using stock fuel pressure. the needle and seat will be able to control 3-3.5lbs of pressure no problem.
Automotive Service Technology Instructor (34 year Fiat mechanic)
75 spider
, 6 Lancia Scorpions, 2018 Abarth Spider, 500X wifes, 500L 3 82 Zagatos. 82 spider 34k original miles, 83 pininfarina, 8 fiat spider parts cars
son has 78 spider
agarair

Re: New Carb, has no fuel return line hookup?

Post by agarair »

Thanks Beek, hopefully I can give it a try next weekend. I have to get this thing running again soon, DixieFest is only about
1 1/2 months away!
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tartan18
Posts: 505
Joined: Sun Mar 13, 2011 10:58 pm
Your car is a: 1975 Fiat 124 Spider
Location: Lebanon, Oregon

Re: New Carb, has no fuel return line hookup?

Post by tartan18 »

While I was told that not having a fuel return line was workable I was also told that having one has a few benefits. One benefit it that it would help keep the fuel cooler as well as purge the fuel tank of any vacuum build up. I don't know if that is true but I went ahead and bought a metal fuel filter that has a return spout. Many Chrysler cars use this filter and my local auto parts store had several to choose from. Mine cost $3.00. I also added a Moeller inline fuel filter just to insure nothing gets into my carb's intake.

My car is a 1975 and I have an EMPI 32/36 DFEV with a mechanical fuel pump.

Image
Jim MacKenzie
1975 Fiat Spider
Finest Italian Automotive Technology
agarair

And another Q, Re: New Carb, has no fuel return line hookup

Post by agarair »

Thanks Jim, that sounds like a good idea and I appreciate the pic, looks like you have a real clean engine compartment.

I notice my new carb (still sitting on the kitchen table) has a small brass connector for a rubber hose below the choke mechanism on the carb body just above the base and to the left of the adjustment screw, anybody know if what this is for? I am guessing it is for a vaccuum tube, but to what?
Toby sends.
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tartan18
Posts: 505
Joined: Sun Mar 13, 2011 10:58 pm
Your car is a: 1975 Fiat 124 Spider
Location: Lebanon, Oregon

Re: New Carb, has no fuel return line hookup?

Post by tartan18 »

It is my understanding that vacuum port is for a mechanical distributor's advance. As I have Mark Allison's Computronix electronic ignition system I simply plugged that port. The only vacuum line I have is connected to my brake booster.
Jim MacKenzie
1975 Fiat Spider
Finest Italian Automotive Technology
agarair

Re: New Carb, has no fuel return line hookup?

Post by agarair »

Thanks to all, 71 is running good with the new DFEV and the 1800 intake manifold. I did put in a fuel filter with the two outlets, one to the fuel return line, works fine. The electric choke works great. I am a happy camper, can't believe I waited this long to do this! Amazing the difference.
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tartan18
Posts: 505
Joined: Sun Mar 13, 2011 10:58 pm
Your car is a: 1975 Fiat 124 Spider
Location: Lebanon, Oregon

Re: New Carb, has no fuel return line hookup?

Post by tartan18 »

Cool beans :D
Jim MacKenzie
1975 Fiat Spider
Finest Italian Automotive Technology
georgeramos
Posts: 1359
Joined: Wed Nov 02, 2011 11:11 am
Your car is a: 1971 124 Spider 1608

Re: New Carb, has no fuel return line hookup?

Post by georgeramos »

Would the DFEV work with the stock dual plane manifold? I am expecting mine to arrive any day and cant wait to bolt it in! I have not swapped manifolds however...

Thanks
agarair

Re: New Carb, has no fuel return line hookup?

Post by agarair »

I am guessing you can bolt it on and it will fit, the dual plane manifold worked with the original 28mm primary barrel, but I suspect based on the difference in manifolds that the 1800 manifold does breathe better with the new carb. When you look at the two side by side, you realize how much more open the chamber is on the 1800 manifold. The 1800 manifold actually frees up a little space in the engine compartment as it is not as deep on one side. I had to shorten the linkage connector on my 71 to make the linkage hook up properly, but that was pretty easy to do.

Any else out there know if the stock manifold will work OK or will there be any problems?
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bradartigue
Posts: 2183
Joined: Thu Sep 20, 2007 2:35 pm
Your car is a: 1970 Sport Spider
Location: Atlanta, GA

Re: New Carb, has no fuel return line hookup?

Post by bradartigue »

georgeramos wrote:Would the DFEV work with the stock dual plane manifold? I am expecting mine to arrive any day and cant wait to bolt it in! I have not swapped manifolds however...

Thanks
It will work. You lose quite a bit of oooomph with that manifold. It is restrictive.

However, it will work considerably better than the DHSA or ADHA carburetors that were originally installed on dual planes.
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