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MG MGA - Fuel lines

The fuel lines under the bonnet and between the carbs on my 1500 are made of a sort of clear plastic. It's old and hard and yellowed now. I never see this on other cars. I'm wondering, is this some sort of customization or were they originally this way? The replacement parts available from the usual suspects are not like this at all.
Steve Trovato

Steve...I've seen these on most of the old carb sets I come across. I would think this was the oem part, as those carbs always looked like they were never touched...someone else can confirm or correct originality I'm sure. They are usually replaced with metal-braid-covered types. The only benefit from the originally clear type is seeing the fuel (and that cursed air bubble) there. The braided lines look better to me...even when dirty...
Jon Bachelor

Steve, unless you need the original equipment for coucours display I highly recommend replacing with the braided steel lines as Jon describes. It is a lot more fire resistant than the clear plastic line in the event of a carb fire.
Bill Young

I am not sure that plastic pipes were ever original specification on the MGA. Certainly, Clausager's 'Original MGA' makes no mention of them. Page 66 states: "The flexible pipes from the main feed pipe to the rear carburettor, and between the carburettors, were braided steel Petroflex from Smiths."

Steve
Steve Gyles

Are the plastic pipes possibly the originals with the mesh covering removed?
John DeWolf

I very much doubt that the original tubes were clear plastic under the braiding. All the ones I've seen are a type of black rubber. I also doubt that this braiding could be removed without damaging the hose beyound use. What usually happens is the rubber deteriorates and the hose begins to leak. It's then possible to cut the hose, remove the fittings (they have a "barbed" end) and install a piece of clear fuel line as a fix.

GTF
G T Foster

I don't think the plastic was under braiding. The ends certainly don't show any fittings that would go around braiding, like on replacement assemblies I have seen. Whether the plastic was ever used by the factory was the thing I was curious about. The fittings the plastic goes on seem so correct for the plastic, that I was inclined to think it was original. The possibility that the fittings on the rubber hose could have a clear fuel line used as a replacement is an interesting idea. Maybe that's it. I don't know for sure though. As for fire safety, Bill is probably right, but clear plastic is sold today as fuel line, so it can't be that bad.
Steve Trovato

How is the tubing clamped to the end fitting. If it is any type of removable clamp, such as a ratchet hose clamp or wire clamp, then the tubing is almost certainly aftermarket. I agree that it is probably a case of reusing original end fittings with newer tubing.
John DeWolf

SU make after market single and double banjos for push on 5/16 inch hoses so no need to mess around with the old screw-on attachments if you wish to go down that route.

Personally, having had an engine fire many years ago on a German Autobhan in a Ford Cortina (1968 vintage but almost new when I owned it) I would never compromise with fuel fittings. As much armour plating for me as possible!

Steve
Steve Gyles

John, Mine has no external clamp at all.
Steve Trovato

That nice shiney brading on the flexible petrol lines also helps to reduce the chance of vapour-lock on those hot days.
Pete
Pete Tipping

I always thought that you wouldn't really get vapor lock when the fuel pump is mounted in the rear of the car and "pushing". If any fuel were to vaporize in the line, the fuel pushing from the back of the car should just push the vapor and fuel into the carbs. With an engine mounted fuel pump, the pump would have to pull on vapor, which is a rather difficult thing to do. This is where the vapor lock would occur.
Steve Trovato

Steve
Vapour lock is simply a question of when the fuel boils really. With hot weather, everything is that bit hotter. When you add up the extra heat in the hotter tank and fuel lines, hotter carbs and hotter float chambers on a very hot engine and you are in a traffic jam; the fuel flow is now very slow and so gets much hotter. If it boils you have vapour. I guess jets aren't set up for this stuff.

When you accelerate again loads of cooler fuel from the tank comes through and air starts coming through the engine bay and all is OK again.

When you switch off the fuel flows stops; so even the small flow of cooler fuel isn't there to help keep things cool. There's no engine fan or water pump, so the whole lot gets a lot hotter before any cooling finally starts to take place.

This is why if you need to start a very hot engine, you apply loads of throttle while cranking the starter to get loads of fresh cool fuel through to clear the vapour. Naturally you ease off the throttle the instant it fires up!

So every little thing you can do to keep the fuel cool will help. The stainless steel braided rubber fuel lines will reflect heat (if shiney) and conduct heat away from a hot spot, the rubber is a good insulator and the large surface area of the brading will keep cooler in the air flow too. Every little bit helps.
Pete
Pete Tipping

This thread was discussed between 10/05/2005 and 14/05/2005

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