6-BBL / 6 Pack & Hemi 3/8" fuel line FUEL VAPOR SEPARATOR/FILTER w/Braided fuel lines. How to incorporate as factory did? Or don't bother?

[biomedtechguy]

@RJRENTON @HEMI-ITIS @davek @6PKRTSE @68 HEMI GTS @66Satellite47 and I'm sure I'm missing some of the best who I hope will join in this thread...
Here's the story, and I believe I need to change up my configuration:
When I got my V-code 70 Roadrunner, it already had the (very nice) WIX 33033 3/8" fuel filter at the front end of the factory (440 6bbl/426 Hemi) 3/8" fuel line. WIX 33033:

I now know that an inline, "fine" (20 micron) fuel filter before the fuel pump is not the consensus, but a fine filter between the pump and carbs is good or acceptable. Here's how my setup is now, since I switched to the braided lower and upper fuel lines. From 3/8" fuel line coming towards the engine:
WIX 33033 filter

..goes IN to the Carter M6903 "stock" pressure, double volume mech fuel pump..

..and then from the pump into the lower fuel line and UP to the Promax inline 40 micron fuel filter..

..and what it looks like from the factory, the way the Chrysler engineers laid it out, before jokers like me think I can one-up the guys who created the 426 HEMI lol...

My CONCERNs although I am not aware of having any symptoms because of these:
*Not enough fuel flow because of the WIX filter being located before the fuel pump...
*Excessive fuel pressure at my carbs because the Fuel Vapor Separator/Filter bleeds off pressure via the .060 return nipple to 1/4" return line
My fuel pressure gauge bounces I assume from the pump "strokes" via the pump rod and cam eccentric. It has read over the recommended max pressure, maybe 7 or so vs ideal being what? 4.5 or so?
So I've got these nice, neat connections and braided lines and so on, but if I (we) were to conclude that I should
re-incorporate the new vapor module back into my system, any suggestions for what hardware to get and how to make it NOT look like a can of mashed ***?

Thanks in advance!

 

[davek]

I dont see how you could use the lower braided line if you added the FS. Are you having vapor lock on the car? I live in SC and never ran the FS on my charger that had the 6 pack setup. It gets smoking hot here in the summer. If you dont care for it being factory correct and it works leave it be. If you are having vapor lock then I would get a shorter braided line and add the FS. I believe you drive your car alot more then I do so you might need the FS.I bought the thick carb gaskets and was disappointed in them IMO junk,yet back to the factory carb gaskets.

 

[bearman]

Bio, are you setting fuel delivery for the new engine. Will 3/8 handle the new engine or will you need to redue the fuel delivery again.

 

[biomedtechguy]

I dont see how you could use the lower braided line if you added the FS.

See! If it was an easy answer I wouldn't have to ask..

Are you having vapor lock on the car?

No sir, not in over 9 years in the South Louisiana swamp!

If you dont care for it being factory correct

That ship not only left port, it's been in the middle of the Pacific Ocean for the entire voyage.

I bought the thick carb gaskets and was disappointed in them IMO junk,yet back to the factory carb gaskets.

I had a BIG problem with heat transferring into the 3 Rochester 2bbl carbs on the 421 Tripower in my wife's 65 GTO. It was SO BAD that I witnessed the fuel literally boiling out of the fuel line fitting going in to one of them, which was good that I found a "leak" but with the way that pressure was pushing on the fuel system, at WAY higher pressure than the mechanical fuel pump ever could, it may never have leaked under "normal" conditions.
I'm sharing that because I found a 2-part solution that has worked 100% and the problem is gone:
I blocked off the heat riser port on each side of the cast iron intake manifold AND used the CoolCarb heat shield system.
Here's the website:
- Home

 

[biomedtechguy]

Bio, are you setting fuel delivery for the new engine. Will 3/8 handle the new engine or will you need to redue the fuel delivery again.

No, I'm haven't done anything yet with the factory 3/8ths fuel system other than the Carter M6903 fuel pump, which I was switching to before I had solid new engine plans. I've thought about the fuel system upgrade, volume of the M6903 is 120 GPH so I don't know what the stroker will require but I'm planning on using my Promax modded Holley 6bbl carbs and the Indy ModMan intake, hopefully with the "Doug aka DVW" mods.

 

[Dragon Slayer]

Fuel spec pressure was higher for the hemi and 6 pack. Despite what some say regarding the separator, the SVM had you read pressure at the carb inlet, so the return was included.

The 6903 has a smaller chamber than the hemi 4024 pump. Volume of the pump is what the motor wants and when you don't need it the float closes the chamber needle seat. The pump arm hangs up and system max pressure is based on the diaphragm spring. Higher pressure harder for fuel to vaporize.

SO, as long as the orifice of the needle and seat are stock with stock floats. Your SVM pressure should be fine. The newer Carbs like edlebrock use different float and seats, hence the lower pressure requirement. Lower pressure means more susceptible to vapor in fuel though.

The Hemi dual quad used the separator so return did not seem like an issue, and you could put a throttle valve in the return to control it.

If no vapor lock, I think you're better off using a filter after the pump and before the carbs. Doesn't tank have sock to block bigger junk in fuel tank?

 

[pnora]

@RJRENTON @HEMI-ITIS @davek @6PKRTSE @68 HEMI GTS @66Satellite47 and I'm sure I'm missing some of the best who I hope will join in this thread...
Here's the story, and I believe I need to change up my configuration:
When I got my V-code 70 Roadrunner, it already had the (very nice) WIX 33033 3/8" fuel filter at the front end of the factory (440 6bbl/426 Hemi) 3/8" fuel line. WIX 33033:
View attachment 1471458
I now know that an inline, "fine" (20 micron) fuel filter before the fuel pump is not the consensus, but a fine filter between the pump and carbs is good or acceptable. Here's how my setup is now, since I switched to the braided lower and upper fuel lines. From 3/8" fuel line coming towards the engine:
WIX 33033 filter View attachment 1471463
..goes IN to the Carter M6903 "stock" pressure, double volume mech fuel pump..
View attachment 1471465
..and then from the pump into the lower fuel line and UP to the Promax inline 40 micron fuel filter..View attachment 1471467View attachment 1471468
..and what it looks like from the factory, the way the Chrysler engineers laid it out, before jokers like me think I can one-up the guys who created the 426 HEMI lol...
View attachment 1471472

My CONCERNs although I am not aware of having any symptoms because of these:
*Not enough fuel flow because of the WIX filter being located before the fuel pump...
*Excessive fuel pressure at my carbs because the Fuel Vapor Separator/Filter bleeds off pressure via the .060 return nipple to 1/4" return line
My fuel pressure gauge bounces I assume from the pump "strokes" via the pump rod and cam eccentric. It has read over the recommended max pressure, maybe 7 or so vs ideal being what? 4.5 or so?
So I've got these nice, neat connections and braided lines and so on, but if I (we) were to conclude that I should
re-incorporate the new vapor module back into my system, any suggestions for what hardware to get and how to make it NOT look like a can of mashed ***?
View attachment 1471483View attachment 1471484
Thanks in advance!

So you want to use the 3 line separator with your AN lines? What size AN?

 

[biomedtechguy]

Fuel spec pressure was higher for the hemi and 6 pack. Despite what some say regarding the separator, the SVM had you read pressure at the carb inlet, so the return was included.

@Dragon Slayer
Is "SVM" Service Manual?? If not, what is SVM please? I have the 2 volume Factory Service Manual for 1970 Plymouth. Do you know the fuel pressure spec for the 6bbl?
The function of "regulating" fuel pressure, or at least providing a "bleed off route" as I understand it, is probably the main reason why I want to reinstall the fuel vapor canister.

 

[Dragon Slayer]

Yes service manual. My 70 list hemi 7 to 8.5psi and 440 HP with Carter 4845S fuel pump as 6 to 7.5psi.

 

[biomedtechguy]

THANKS to everyone, and for all the help and suggestions! The "running bad problem" I've had since October...
IT'S FIXED!!

 

[70sixpkrt]

How was it fixed?

 

[biomedtechguy]

How was it fixed?

Just in case you don't know, I had started a thread in October last year when I was having a real problem with my 440 6bbl running poorly, that I wasn't aware of until Cruisin the Coast had begun, the ONE week I actually try to have fun in my life.
So I knew that in the 5+ years my Autolite 85 spark plugs have been in, they have been through some "rich" operating conditions, and the one or 2 I can easily get to were black, and smelled like gas.
So I started that thread in the ignition forum, ran into problems with a bad thread plug hole, and I was trying ignition system stuff because it was easy to check, fix, and seemed a likely villain.
The spark plugs certainly needed changing, but that nor any other ignition system stuff fixed the problem.
It turned out to be a POWER VALVE problem, it was "crusty" from moisture in the center carb, and the symptoms (too rich, gasoline smell, gas smell on spark plugs, and "surging/jerking" rough running under part throttle, steady state throttle, and gentle increase of throttle conditions, and none of the 6 idle mixture screws had the effect on my idle speed that they should)
It was really running bad!
Since I changed out the power valve, and while I was "at it" I took the fuel bowl off all 3 carbs, sprayed them all out w/carb cleaner, and put it all back together IT RUNS GREAT! I mean the difference is dramatic! I still need to get all 6 idle mixture screws adjusted, but I am amazed at how good it runs under the same throttle conditions that it was running so badly under.

The reason why I started THIS thread about the fuel vapor filter/separator is because I have always had a "fine" 20 micron fuel filter before my Carter M6903 fuel pump, AND I have the inline washable, reusable 40 micron filter that came with the lower braided line from Promax. I think the 100% consensus is NO fuel filter should be before the fuel pump, definitely not a fine micron filter, and the fuel vapor separator has a "regulating effect" on fuel pressure, and acts as a course filter. With the problem I just fixed, I want to do all I can to alleviate fuel system problems.