I guess I'm eliminating the fuel vapor separator from my 70 440+6bbl

[biomedtechguy]

I was going to reinstall the fuel vapor separator, but the shop saw the line was plugged off and he cut the return line way back by the tank. The owner says when I install my 541 stroker the Carter M6903 120 GPH mechanical pump isn't going to provide the required fuel reliably.
He says that the factory 3/8th" Hemi/6bbl fuel feed line is something I'm going to want to replace with a bigger line when I'm ready to install the 541, and use an electronic fuel pump and fuel pressure regulator. We both agree on a return line rather than dead heading the fuel system.
I am going to be using my Promax modded Holley 6bbl carbs. Expected HP/Torque is mid 6XX to 700.
Any comments on the elimination of the fuel vapor separator guys? How important is it for me to put it back in, or given what's coming (hopefully by October 2021) don't bother?

 

[dadsbee]

I have a hard time believing that a 3/8 line and a 120 GPH pump ( TWO GALLONS PER MINUTE) pump can't keep it breathing!..or I'd have gone down in the trees by now!

 

[F4R/T]

I don’t know I’d try to go with it first and do a trial and error method, although my 505 I was told 1/2”.. no comments on that I recall about the return line. Many new fuel injected vehicles don’t have return lines any more so it’s up to you.

 

[biomedtechguy]

I don't have any argument against using the 3/8ths line and the very popular among 6bbl race guys, Bob "Mr. Six Pack K" included, Carter M6903 mech fuel pump since I already have them, albeit they are running 440s not 541s.
If I get indications of fuel starvation, then I'll know.
What about an electric fuel pump as a pusher "booster" and keep the M6903 in place? Or if I go electric fuel pump I should drop the mechanical fuel pump all together?
What about the fuel vapor separator?
Should I really do the work to reinstall it or no advantage to it for performance and cruising roads and highways?

 

[biomedtechguy]

I have a hard time believing that a 3/8 line and a 120 GPH pump ( TWO GALLONS PER MINUTE) pump can't keep it breathing!..or I'd have gone down in the trees by now!

Tell me about your engine build please.

 

[dadsbee]

480 HP .. 52 US GPH fuel burn on take off.. through a 3/8"fuel line. You'll never run full throttle as long as I do,,,,

 

[biomedtechguy]

480 HP .. 52 US GPH fuel burn on take off.. through a 3/8"fuel line.

Now I understand the "down in the trees" comment, but I'm a little confused about this quote. Is your plane's fuel pump rated for 52GPH or is 52GPH the rate of consumption on takeoff at 480HP or???

 

[dadsbee]

It's burning, at minimum, 52 US gallons / hr of fuel, for over 5 minutes on take off. Can't see your car ever touching that need.

 

[biomedtechguy]

Thank you!

 

[66Satellite47]

I'm a believer in large fuel lines. The suction side of pumps is very critical. I don't use a mechanical pump, electric 140 Mallory at the rear, 2- #6 wyed into #8 going into the pump, 1/2"/#8 from pump to regulator at the firewall, 2-#8 to the carb inlet. Over kill, probably. Pretty sure won't see fuel starvation. BTW line losses on the suction side of a can kill the actual fuel pump delivery. It can result in cavitation, limit the output.

 

[4406bbl]

A sump in the tank is the best thing you can do. If you street drive in the heat a lot use the return, some years pontiacs use a 3/8 filter with the 1/4 return and the 1/16 restrictor is in there. Gf16 I think it was.

 

[biomedtechguy]

A sump in the tank is the best thing you can do.

He included that in the discussion, and I agreed.

If you street drive in the heat a lot use the return

There's no debate about that. I definitely will setup a return line if/when I go with an electronic fuel pump.

 

[F4R/T]

Way cool prop jobs dads bee! Love to go for a ride! I know I jumped off subject— sorry

 

[4406bbl]

G18 fram gf73 ac

 

[4406bbl]

You can make your own use a tee and solder up a fitting with a 1/16 hole, try to locate it at the top, pointing up, of the fuel system to get the air bubbles out. Factory one has a screen to help do that and to get the chunks out. I assume you have a filter somewhere, if not g18 may be your friend, filter must be on pressure side, only screens on suction side.

 

[biomedtechguy]

I have the fuel vapor separator that was on my car AND a new one I bought from Mancini Racing.
I am polling the forum to see if there is a performance or other significant benefit to reincorporate it into my fuel system.
I removed it when I installed the Carter M6903 and plugged the return line. The mechanic working on my car saw that it was plugged and cut it way back by the tank. I'm trying to determine if I should reinstall it and why.
I also have a WIX fuel filter on the engine end of my 3/8ths factory fuel line, between the gas tank and fuel pump, and then a 40 micron reusable fuel filter in the Promax line right before it branches off into 3 individual carb lines. That is another topic that has different opinions as to Y/N some say no to a filter where my WIX is, I think it's a good idea to keep crap out of my fuel pump, and then the 40 micron filter prevents any debris that could be generated by the pump itself from getting into the carbs.
I dunno....

 

[HEMI-ITIS]

IMO go with the larger lines now.You can NEVER have to much fuel pump and delivery system.
I use a Magna 500 pump with filter on my twin carb deal. I could see an Aeromotive set up in the tank for you.

 

[biomedtechguy]

I could see an Aeromotive set up in the tank for you.

Can you post a link to the specific product?

IMO go with the larger lines now.

Yeah..well that is going to have to be on the "541 pre-installation" list because I have to pay a big labor bill for everything that's been and is being done, incidental parts that have come up through the process, and Cruisin the Coast starting October 4th.
I appreciate the advice!

 

[HEMI-ITIS]

https://aeromotiveinc.com/product-category/fuel-pumps/in-tank/

 

[Sixpactogo]

I can't imagine needing more than a 3/8" line but what do I know......On the subject of the separator, I always assumed it was there because of vapor lock issues. Back in 68, my brother and I both had 68 Charger 4 speed cars. His was a 383 while mine was a 440. While we were racing on week-ends in Wentzville MO during the summer of 68 with temps around 100F, his car would vapor lock quite often while mine never did. What we came up with was the fact that my car had the 3/8" line and 1/4" return and his had the 5/16" line with no return. We robbed the parts from a wrecked R/T for his car and never had problems with vapor lock again. IMO, Mopar would not have added the separator and return if it was not needed.