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Weber dcoe40 install help with fuel system.

 
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Paulyy  



Joined: 05 May 2014
Posts: 87
Location: Melbourne

PostPosted: Wed Dec 13, 2017 4:10 pm    Post subject: Weber dcoe40 install help with fuel system. Reply with quote

Iíve got the carbs, I now have the right jetting.

We have dellorto dhla 40s on there running (terribly) with a redline FPR and the stock fuel pump. I have the fpr on the return line so the fuel goes in both carbs then out to the fpr on the return.
Does that sound right?

The dellortos are old and probably jetted wrong as we havenít touched the jets, we just tried to get the car running with them in the first place. Which it turns on and revs.

So I have the Webers. New. Jetted to the 924 spec. Now I want to put them on and make sure the fueling is right so I donít break anything.

Thanks.
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 1549
Location: Not Detriot - NMI

PostPosted: Thu Dec 14, 2017 7:04 am    Post subject: Re: Weber dcoe40 install help with fuel system. Reply with quote

Paulyy wrote:

We have dellorto dhla 40s on there running (terribly) with a redline FPR and the stock fuel pump. I have the fpr on the return line so the fuel goes in both carbs then out to the fpr on the return.
Does that sound right?


IDK about those carbs in particular but NO..
So you are pretty much trapping max fuel pump pressure in your carbs?

I think you need to so something more like..

Gas tank-fuel pump-Fuel line T-pressure regulator-return line-Fuel line T- Fuel tank

And you need to go..
Pressure side T-carb in-carb out-return side T

I think you only want like 5psi into your carb and then 0psi out of your carb..

I don't know what kind of FPR you are using, ho many ports and what they do, how it's designed to work, or if your carbs are quite different than usual, but it should be something more like this..


Or like this..

Or with a carb return line T back to the return line like I was saying..


Depends on what kind of FPR you are working with but I don't know of any carburetor that wants a system pressure trapped in it like a CIS distributor..
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Fifty50Plus  



Joined: 28 Feb 2008
Posts: 1000
Location: Washington DC area

PostPosted: Thu Dec 14, 2017 9:10 am    Post subject: Reply with quote

Like Eddie says for the routing. Solex, Weber and Dellorto carbs don't like more than about 3 1/2 pounds fuel pressure. More like 2 -3 pounds.
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Paulyy  



Joined: 05 May 2014
Posts: 87
Location: Melbourne

PostPosted: Thu Dec 14, 2017 12:29 pm    Post subject: Reply with quote

The FPR im using is this Redline one,
http://garage.ideola.com/prod-EngineMods.html#weber

1 In and 1 out.

I set it up how you'd set up a normal fuel rail. Fuel goes into the rail, then out of the FPR keeping equal pressure though the rail.

So with carbs, there's no return i assume from those images. Except the last one with a bypass.

I do understand about the 2psi thats needed.
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MikeJinCO  



Joined: 08 Jun 2010
Posts: 716
Location: Maysville, Colorado

PostPosted: Fri Dec 15, 2017 2:03 am    Post subject: Reply with quote

A fuel return line from the regulator isn't required. I use a Holly 12-804 FP regulator. It might be easier to run a return as the difficult part was finding a cap for the existing return line. Finally found one made by Vibrant Performance It is like a 12x1.5 or 14x1.4 pipe cap which is not easy to find in this country. I am going to try to use the standard NA fuel filter when I tested it with a low pressure fuel pump it worked. Again the fittings are hard to find and they came from Vibrant Performance thru Summit Racing. The inlet and outlet are different sizes.
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Paulyy  



Joined: 05 May 2014
Posts: 87
Location: Melbourne

PostPosted: Fri Dec 15, 2017 2:15 am    Post subject: Reply with quote

I got it now plumbed like the 2nd image. and have 2psi to the carbs.
Soon i'll get the webers on. will update. Hopefully they are turn key.
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