Ideal triple carb fuel supply setup

[Dave240Z]

So just what is the ideal triple carb fuel supply setup? I honestly don't know for sure. There's so much conflicting info it's hard to tell whats up from down. I have heard all kinds of conflicting stories, and without dumping lots of $$$ on my part to test them all out I thought I'd try and see what the collective wisdom is out there with regard to this. Maybe the best way to approach this would be with a series of questions or common statements and we can pick them apart as we go. Also state your current setup and your impressions.

 

1) You need a return line - Yes/No?

2) If you need a return line, where do you plumb it? After the last carb or after the regulator? I've seen both.

3) Is the stock mechanical pump adequate? My guess would be no due to volume concerns.

4) Do you feed all carbs inline or individually?

5)

 

My current setup:

Pump: Holley Red

Regulator: Holley w/ gauge

Return Line: None

Impressions: I personally think something is not quite right about my setup.

First, it's rather noisy, but I can live with that if needed.

Second, the car seems to want to stall more often, whereas it didn't when I had a cheapy electric pump installed.

Third: I can never get the regulator to stabilize. Once I think it's stable, the next time I start the car and look at it, it's reading different. I can't figure out why it's not consistent.

 

Here's a graphical representation of how it looks:

 

PUMP -------REGULATOR------CARB 1-----CARB 2----CARB3

|

GAUGE

 

TopEnd performance (our favorite supplier ) seems to have setup a webpage for weber carbs. They even have a section related to fuel delivery options, and basically blast my setup as not being very good. Can't say I disagree with them really. Here's the address:

http://www.racetep.com/webfuelspark.html#webfaq

 

Your thoughts?

[ZR8ED]

Hi Dave long time no see..

 

I have run several different configurations when I ran the triples.

 

1= yes

2= use fuel return line (do 240's have one stock?..my 280 does)

2a=practical way to plumb the system is to mount the regulator on the firewall (passenger side) have the main line come up from under the regulator and have it exit the regulator towards the drivers side. Run the fuel line (steel or steel braided) and have it make a nice easy curve (90 degrees) to line up with the first rearmost carb. You need 'T" style banjo fittings and simply run each section of fuel line to each carb in line... the last carb (front carb) should have a "T" banjo joint as well and run more fuel line infront of the valve cover (I prefer ss braided lines) and run the line past the valve cover and over to the frame rail. (280's have the return line here) and simply attach to stock return line and clean up, use steel lines, or ss braided to make it as clean looking as you like.

 

3= stock mech pump will work, but I believe it is not ideal...

 

4=feed carbs inline..

 

The return line is good for keeping the fuel moving and to reduce chance of fuel perculating in the lines as much as possible. (fuel bowls are still at risk)

 

Your fuel pump is noisy A= holly reds are noisy ( Iknow..I had one as well) It surges because your system is dead headed and only needs fuel as the needle valves open with the floats as fuel is burned.

 

I have run dead headed and inline with a return at the front, as well as return at the back when I had a fuel pump mounted in the engine bay as well... (long story)

 

It ran fine deadheaded, but started nicer in the summer with the return line...

BTW you want your guage on the other side of the fuel reg.. you want to measure pressure after the reg..not before..

 

3.5 psi and a good quality fuel filter... I actually liked the FI filters.. because they were much larger...

 

BTW my holly blue and holly red i had mounted in the stock 280z location... and it was still noisy.

 

Scott