Fuel line from tank to carbs - what dia?

[McBreadhead]

Warning: this a very boring topic.....

 

Need to fit fuel pressure regulator before my twin 40DCOEs which are fed via a 5/16" dia (OD) fuel hose approx 40cm long, ending just below pedal box. This is fed by smaller 8mm dia (OD) hose coming direct from tank/fuel pump under car which inserts directly into bore of 5/16" hose (which conveniently has ID of 8mm).

 

I'm planning to use the Puralator unit which has a variety of fittings, none of which will fit bore of 8mm pipe which is circa 4mm. Smallest is 6mm, then 8mm and 10mm plus other oddities. Demon Tweeks man said 4mm ID is too restrictive for fuel line, with 8mm more usual.

 

Firstly is the 4mm pipe too restrictive and should I upgrade entire fuel line to 5/16" or will fuel regulator effectively restrict flow anyway? Secondly, if not I guess the 8mm tails fitting is the one to go for but this means further 2 joints and jubilees on the 5/16" section which are messy and potential failure points.

 

What do other people use? (It's a 160 bhp cross flow running a Facet fuel pump).

 

Ta very much for advice

[McBreadhead]

I know it's boring but there must be someone out there with nothing better to do..............?

 

required please

[Guy Lowe]

I run 40's on my standard 2.0L Zetec with a Facet 40147C pump and Purolator regulator, all of which are on 8mm ID hose, right from the tank to the front carb. I bought the Purolator PRO54 which has 8mm inlet/outlet which fits fine.

 

The regulator controls the pressure rather than flow so that the carbs needle valves are not overcome with petrol so a large hose would work ok, but not one that is too small.

 

Having said all that, when I fitted the pump/regulator I bought 3 metres of good quality 8mm fuel hose, a box of clips (not worm drive) and replaced the lot

 

Guy _SB Lowe _{o *arrowup*o}

The ZETEC is now running here

 

[Crudders]

McB - the fuel plumbing on my 135BHP crossflow with Facet solid state pump, Purolator pressure regulator and twin 40DCOEs is 5/16" / 8mm (same thing bar a few thou) throughout. The bore inevitably reduces at unions but so long as this isn't appreciably less than the ID of the final union at the carb (4mm or so?) I don't see a problem. The only time I've suffered fuel starvation was with the original mechanical fuel pump.

 

Crudders

[DaveMorris]

I was going to post "Do you really need a regulator with such small bore pipe" but thought better of it

Dave.

 

Ed to add - No need for anyone to explain about pressure drop / flowrate / calculations.

 

X-flow(er) powered

 

Edited by - DaveMorris on 2 May 2007 16:19:35

[McBreadhead]

Dear all,

 

Thanks for advice, looks like I will be re-plumbing fuel ine with proper 8mm ID pipe then. What a pain as the professionals only renewed fuel line with the wee 4mm pipe last summer which they charged for.

 

 

[McBreadhead]

Out of interest does anyone know what the CC original pipe dia was? Think it was a Rover part from previously related threads.

[millsn]

If you;re re piping I'd do it in fuel injection rated pipe to future proof yourself. Long time aqgo I did this which one day mot so long ago helped me a little

[Guy Lowe]

I used fuel injection hose, it slightly more expensive but worth it IMO

 

Guy _SB Lowe _{o *arrowup*o}

The ZETEC is now running here