Yet... another DCNF question!

[Rooster]

Project race X is in full steam and I need to sort out the fuel system. As of right now, I have the original tank in the car, but am converting to a front fuel cell. For this purpose, it really doesn't matter what I am using to store the fuel, as the question pertains to fuel delivery. I will be running dual 40mm DCNF's, I have a stock mechanical fuel pump. I know I have to upgrade, are their any magic numbers I should look for. specifically, gph and psi. Also, I noticed the DCNF's do not have a return line to the tank (like the stock carb), I'm assuming that if I run a higher pressure elec. fuel pump I'll need a fuel regulator. This is planned anyways, but my question is, why is their not a return line?

Thanks, as always, for the help!

 

[fastx19]

Fuel and DCNF's

Hi.

Each carb needs to have 3.5psi of fuel, not for both, but each. So, this would say you need a fuel pump capable of a sustained 7psi of flow.

Fuel pressure regulator is vital as well.

You can setup a return line however I have found at times this can cause a starvation issue if the return is too large. I have heard of other people putting a jet into the fuel line to limit the return to the tank.

The primary idea behind this is to eliminate vapor lock.

Hope this helps.

Eric

 

[Rooster]

Thanks Eric, that indeed helps!

 

[wannabfast]

Hi.

Each carb needs to have 3.5psi of fuel, not for both, but each. So, this would say you need a fuel pump capable of a sustained 7psi of flow.

hmm thats interesting, i have my fuel pressure regulator set to 2psi... running fine here!

 

[TonyK]

Correction

If you have a pump capable of sustaining 7 PSI then you will need a fuel regulator to drop it back to 3.5 PSI.

Pressure is the result of restriction of flow and the pump's capacity to maintain it. If you have pump that can maintain a flow of a litre minute a 3.5 PSI you will be fine. DCNF carb's don't require a lot of pressure to operate. 7 PSI will be too high.

TonyK.

Grimsby Ontario Canada.