Fuel Lines

[Neil-yaj396]

What size are the fuel lines on a standard carb model. Delivery (steel pipe to pump to carb) and the significantly smaller return pipe? I have a leak either on the pipe into the pump or the return from the carb, most likely the former.

[HFStuart]

8mm and 6mm on mine but you could get away with 5/16" & 1/4".

Stuart

[Neil-yaj396]

6mm (outer) is too big for my return pipe, although I've used a piece as a temporary repair on the pipe to the pump. I've ordered some 4mm.

[mangocrazy]

Pardon my ignorance, but is a send and return fuel line only required if you're using the original mechanical fuel pump? I've fitted an electrical (Huco) fuel pump to my Spider and was advised that I could dispense with the return line. Is this correct?

[HFStuart]

The Huco is a low pressure pump so you don't need the return - in fact I found my car wouldn't run with the return connected as there wasn't enough pressure at the needle valve.

BUT

There is the risk of fuel vaporising in the supply line if you're using the pump to pull from the engine bay rather than push from the tank - in this case the return pipe keeps the fuel circulating and keeps it cool. If your pump is close to the tank it shouldn't be an issue.

I run a return line with my Facet Silver Top pump and have had no issues.

NB I found the Huco pump didn't deliver enough fuel at full load when I used one and the mixture went dangerously lean. It might be worth checking yours.

Stuart

[mangocrazy]

Hi Stuart,

Many thanks for the response. I have to admit I very rarely (if ever) give the car 'full load' these days; I'm tending to give it an easy life until its had a full engine makeover, in the interests of longevity. For my current usage profile, I think the Huco is sufficient. When I do the twin DCOE conversion, I'll definitely move to a Facet pump and mount it in the boot. It would also be a good time to completely renew the fuel lines.

The only thing that bothers me with a boot-mounted fuel pump is having to cut holes in the floor for the new fuel lines. Is there any way to avoid this?

Graham

[Spyder79]

Stuart,

as you know I have twin 40 dellortos in my Spyder and a Huco pump under the bonett with no return pipe to the tank.
I was suffering with pinking in the summer months , and retimed it , color tuned it , used super unleaded with a lead additive , but still it pinked.
I was only thinking this week that it was because the trumpets are right behind the radiator and quite close , therefore the air was too hot , reducing its ability to ignite properley when compressed.

It runs beautifully in this weather with loads of torque.

Do you think it is because it needs a cold air intake or that it needs a fuel return line? or both.
My fuel return is blanked off and i dont know where i would connect it on the dellortos?
Also , any idea where to get an air box or how to make one or make something that would improve it.
I have ramflow air filters that fit over each set of trumpets.

the photo show k+n's but i took them off due to fouling with the alternator and sparking ....... which i thought quite dangerous!!!!

thanks

[Spyder79]

This is a picture with the ramair filters....

need to figure a way of feeding them with cold air??

[HFStuart]

I can't see a fuel return line helping here and with the low pressure Huco I can't think of an easy way to connect one and still deliver enough fuel to the carbs.

TBH a rear mouned higher pressure pump and a pressure regulator are the best bet for twin 40s, they've a bit more capacity in reserve.

If the issue is the carbs sucking on hot air this probably won't cure the pinking though.

A cold air feed  / airbox would be certainly beneficial  - those foam socks will be drawing hot air straight out of the radiator ! I'm not the best preson to comment on that - perhaps Eric or someone else more experienced could give a few pointers?

Re the siting of the pump - I don't know what others have done but I'd put the pump on the underside of the car near the rear crossmember rather than in the boot itself. There looks to be space there and the fuel lines run that way anyway.

Stuart

[mangocrazy]

Hi Staurt, thanks for that. Yes, it clearly makes more sense to mount it under the car, but out of the way of any road debris. I'll get the car on some ramps and have a good look around. A good sturdy bracket with a front-facing debris shield sounds favourite.

With regard to Spyder79's problem, I saw a very nice piece of work on someone's Beta a while back that involved aluminium ducting to route the hot air from the rad downwards and out of the way of the carbs. It was a fairly substantial piece of work and clearly wasn't knocked up in 5 minutes, though. It was made out of that 'embossed' ali sheet that is used for walkways etc. Doing that means that the carbs breathe cooler air that hasn't been through the rad.

Can't remember now where I saw it, but if I remember I'll post pics or a link. Quite possibly on Guy Croft's site.

[WestonE]

Spyder 79

Make a curved shield in Aluminium from the top of the radiator swept down under the intake socks to deflect hot air under the carbs. Making it in card first helps and you can look at pictures of these things on John Day's old Beta Copue race car. Then remove the top air cowl on the radiator if there is one (photos do not show when replying) and or fit an air pipe from the handy round hole on the left/ NS of the enigine bay pointed at the side of the air intakes. Even better if you can do it from both sides or even buy a Pipercross airbox with a cone filter on the end low down on the left in the cold air stream.

Hot air in the intakes kills power (10bhp or more) and often engines through detonation which can be mistaken for pinking until it melts your pistons or blows the head gasket to bits. BTW Weak fuel mixture also leads to detonation and insufficient fuel delivery will do this. On Betas with twin 45s a Facet Silver top interupter pump does NOT need a return line, but does need a pressure regulator and inline filter. Hence Filterkings are often used.

The fuel lines on carb Beta's cross over the exhaust pipe which heats the fuel leading to issues in some climates. Best to wrap them with insulation in that area. 

People also forget to change the Sparkplugs when tuning the engines I use NGK BR9 EIX Iridium in my 200BHP FI Montecarlo as they clear well even when the engine is cold. Even IE Betas used 7 grade plugs.

Eric       

[mangocrazy]

The fuel lines on carb Beta's cross over the exhaust pipe which heats the fuel leading to issues in some climates. Best to wrap them with insulation in that area. 
Eric       

Nice one, Eric. That's something I need to attend to on my Beta. In fact it would probably be best to completely re-route the fuel line well away from the exhaust. What fuel line would you recommend to cope with current (standard) and future (tuned engine with twin DCOE 45s) use?

Graham

[WestonE]

Graham

An 8mm bore rigid line routed like they are on IEs and VX i.e inside the car along the righthand sill and through to the engine bay half way up the firewall to run along the right hand chasis leg. Copper/Nickel pipe from Automec is fine or you can use small bore copper heating pipe from DIY sheds. If you will ever fit FI you want a pair of 8mm pipes as these systems use a pressure regulator on the end of the fuel rail before the return line.

Eric 

[mangocrazy]

Hi Eric,

Thanks for that. Probably an idea to get all the parts I need now and fit them as I have time. I'm pretty sure I've got a reel of 8mm copper pipe at the house in France (would you believe a lot of the existing HW plumbing is 8mm o/d - no, neither did I...) Having said that, I note you say 8mm bore - would that be 10mm o/d pipe?

I presume that a Facet Silver top Interruptor pump with pressure adjuster and filter would work equally well with the standard carbs as with DCOEs?

For the moment I think I have some spare Tri-Iso-9 multifoil insulation lying around that I could lag the fuel pipes with. That should block exhaust heat fairly well.

[WestonE]

Graham

Go for the Facet Silvertop Competition and regulate it down to 3PSI with a Filterking with a guage. The FSE (fuel systems enterprise) website has all this stuff. This will work fine with the existing carb with the return line blanked off at carb and rigid line. A bolt pushed into the hose and the clamp done up works fine. This setup means you can cut the fuel pump lobe off the Aux Driveshaf and plug it thus protecting Number 2 Conrod and not having to worry about setting the Aux DS at 37 degrees exactly when fitting the belt. A LOT of twin cams have been killed by that fuel pump lobe breaking the conrod. Would you believe it is still there on IE, VX and SI Montecarlo models that never had a manual pump from the factory. Pipe is 8mm internal diameter.

Eric     

[mangocrazy]

Thanks Eric, top stuff as usual.