Mopar Muscle Association UK

Morning All,
Firstly a Happy New Year to everyone and your families.
I’m looking at replacing the fuel line on our 72 Duster. Could someone point me in the right direction as to what to use, whether it be solid or flexible and what are your preferred choices.
Andy

Hi there, it depends a lot on the application and engine size.
For a standard engine and road use a solid line 5/16" with suitable flexi E5 / E10 compatible tubing should suffice.

For a Racing application, I would recommend larger bore and possibly Teflon lined braided hose.

Assuming you are just wanting to replace the original, a roll of 5/16” Kunifer from eBay will do the trick. Also assuming you will be replicating the torturous route of the original line, a small hand held bender will help. You’ll need your glamorous assistant as wrangling 20ft of bent line that wants to get caught on everything is always entertaining..

Hi Chaps,
Maybe in the future we may look at going down the route of installing EFI. So want to make sure that what we do is more than adequate to accommodate a fuel pump, etc.

You would need to look at what your chosen EFI system needed for fuel delivery, it might also want a return line. Some systems need a swirl pot and an in tank pump. When I looked at it it all gets very expensive and I really don’t see the benefit over a good carb and a decent tune up, your choice.

Fuel supply is dependant in engine needs, as said you need to check on chosen EFI requirement. As a minimum for EFI, I would be looking at 3/8” supply & return.

I actually had to increase my return line size, as it was becoming a restrictor and took over from the regulator. That said, I have a long run from tank to engine & my engine is not in the normal bracket. ie my supply is 5/8”, 3/4” return.

It’s a fact that a well set up Carb can outperform EFI, assuming all parameters are equal. It’s when those parameters change, EFI can have an advantage. Trust me, when trouble shooting, there’s nothing easier than looking down a carb to confirm you have fuel or checking Dizzy for spark.
Laptops have there advantages for sure & once you understand ECU you have multitudes of tuning opportunities….

At the end of the day, what is your end goal

Edit: Not sure of what EFI, but Fitec would never get in my list of choices. I know quite a few folks who have tried, but eventually removed as troublesome

Thanks for the replies.
After discussion we decided to opt out of going down the EFI route.
So my next question is about installing an electric fuel pump and regulator. What’s best
Also what style of phenolic spacer should we go with on a dual plane intake with a Holley 4160.

A Holley "Blue" pump will be fine, the push as opposed to pull, so will be mounted at the rear near the tank - I would advise putting a replaceable Filter twixt tank and Pump.

Holley Small regulator near the Carburettor. You will get away with dead heading, but you can run a return line if you wish.

You can get the pump and Regulator as a kit.

I assume this is a Small Block?


Good call on ducking the EFI....

4 hole spacer on a dual plane intake. Think about this one, unless you are planning 500hp and 10 second quarter mile passes you really don’t need an electric pump. 3/8” sender and line, Carter competition or Edelbrock mechanical fuel pump with a small Holley regulator will get the job done, is practically bolt on and will give years of trouble free service. You’ll need a pressure gauge and a 3/8” filter before the carb. On the other hand a Holley blue electric pump would do the job but you will find it difficult to mount it at the rear where it needs to go with a stock tank. They are very noisy and not especially reliable especially when a car is laid up over the winter. A Holley black pump is quiet if mounted correctly but is best part of £500. Your choice, I’ve only just fitted an electric pump as I’d found the limits of a mechanical set up as I’ve gone faster, I was more than happy with it up to that point. I should add that apart from now having 5psi fuel pressure, going electric has made not a jot of difference performance wise for the best part of a £1000 outlay.

Couldn’t agree more with Blue, if lower performance, a mech pump is good enough. They supply enough fuel, easy to fit, very quiet & generally hassle free
The drone of an electric pump, especially one dead heading soon wears thin….

Jesus, those mechanical fuel pumps are a bit pricey.

Duster1 wrote: Wed Jan 07, 26 8:01 pm Jesus, those mechanical fuel pumps are a bit pricey.

Im guessing not too dissimilar to the price of a Holley electric pump, good job you decided against EFI if a mech pump seems ouchy

Around the time of the pandemic Carter pumps were nowhere to be had for many months. When they became avilable again they had suddenly lept up in price,it’s the world we live in now. Expensive as they are it’s still the most cost effective solution.

I've just done all my fuel lines with flexis and a mechanical pump (carter).
In line cartridge filter; earls fittings throughout - lovely job and perfectly man enough for my 475hp through a carb.
Dont overthink it if your setup is simple. (I'll fit the return if I ever fit the EFi)

ah you don't have to be american about this. Namely..throw away good standard stuff and replace with slightly better Known brand name, but way more expensive Race stuff.

you can have success with cheaper standardish stuff.


small block fuel pumps

https://www.rockauto.com/en/catalog/dod ... +pump,6256

Big block fuel pumps

https://www.rockauto.com/en/catalog/dod ... +pump,6256

doesn't need to be special

just needs to work

pump for 440 v8 or pump for slant 6 costs about the same...

most aftermarket replacement pumps these days over achieve on flow and pressure because the manufacturers are lazy and bang out the same pump for everything with different lever for application

as such buy one for a slant 6 and you get one that can feed a 340 V8

given the cost, if it proves to be not good enough you can then worry about getting an expensive Race focused one


GMB is a japanese manufacturer that gets reboxed by many. An OEM for toyota etc
carter you know
delphi had a history of making bits for GM

so unless you really do plan to race with a massive 700cfm carb id be looking at a 2 tower modern aftermarket standardish none rebuildable pump.

if you have heard of the brand it will probably be ok.

if it pumps too little, don't use the gasket and seal it to the block with sealer..move the lever closer to eccentric cam and you pump more due to slightly bigger throw of the lever.

if it pumps too much or the pressure is too high glue 2 or 3 gaskets together and move it out... shorter throw of the lever = less pumpage


remember mechanical pump designed to be dead headed, and is self regulated to a certain extent. low rpm low pumping high rpm much more pumping

my experience with holley regulators indicates to me at least that they are crap, they set the pressure by completely restricting the flow.... so i gave up with "More things to go wrong" and hang the consequences.

i feed 3 webers, approx 690 CFM of carb, with a GMB slant 6 pump
i do not use 690 CFM of carb... obviously.... i have small motor, that is the potential max my inlet would flow if my cylinder head wasn't so horrible.
i'll be using 300 to 400 of it

if i can do that with a £30 slant 6 pump anything for a 340 or a big block should be ok on a v8 up to a point that may well be beyond what you need.

if you are going to be going Wide open throttle across the line in a race go for the expensive one..not running lean at max power is important

for most else i think standard will be ok but as i have hinted my motor could be potentially half the capacity of yours....so my views on this subject should be taken with this in mind ..... i don't have a v8....

Dave