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MG MGB Technical - Fuel hoses - Which kind is best ?

I am reawakening an MGB which has been on axle stands for 16 years.

All the fuel hoses have perished and need replaced. While I would like to use hose which looks original I notice several different alternatives including clear PVC internaly braided and galvanised steel overbraid and stainless steel overbraid. The original was a plain black plastic hose.

Has anyone any recommendations ?
sam christie

Yes - avoid the braided hoses, when they perish you can't see until fuel leaks.

Avoid the plastic hose which hardens.

Use only plain rubber reinforced hose clearly marked as suitable for fuel.

The club sells it by the metre in 1/4 inch and 5/16 inch internal diameter.

Buy stainless worm drive clips to suit and don't overtighten them.
Chris at Octarine Services

Is the same hose used on the SU HIF carburettors ?
sam christie

Absolutely no reason why not. On HIFs with the link pipe make sure you orientate the worm clips such that they can be tightened with everything else in-situ (which should be the case with all hose clips), although this is probably more of a requirement on V8s. Hoses with worm clips will tend to weep as the rubber distorts under the fixed clip over time and reduces the pressure between hose and tube, whereas the 'constant pressure' spring clip type don't. More of an issue with coolant, though.

If you reuse a clip because it looks OK make sure you can tighten it more than it needs to be when on the hose. I've had a couple in the past where it tightens and stops, but it is the worm that has jammed, it isn't tight on the hose. I also put a dab of Waxoyl on the screw and 'thread' before tightening.
Paul Hunt

The small stainless clips have a very small saddle and don't suffer with uneven clamping pressure like the old "Terry" clips.
Chris at Octarine Services


I would like to order the correct hose as you advise for my car but the various part numbers and descriptions have left me confused.

I have also noticed that there is a good quality 8mm hose available from non MG sources which has a much thicker cross section (presumably for fuel injection systems). As I have mentioned I would like to get hose which looks as original. Which part number is appropriate for a length of the correct 8mm hose ?

I have ordered some of the constant pressure clips.
sam christie

To answer my own question the part number is CDU2283M but this is not necessarily the same as the original.

The MGOC Spares person I spoke to on the 'phone could not tell me the outside diameter and he suggested I order some and send it back if it was not right. I had already received some UKC3794 clips.

Another source - MG Parts UK - said the CDU2283M which they have is of a larger outside diameter.

The original dimension hose was 8mm inside and 12mm outside.

The pity is that the 'constant pressure' spring clips I ordered from the MGOC will not fit the modern hose (15mm OD) - or at least I have tried and I can't get them to go on. And even if the clip would go the material is so stiff it will not compress like the relatively soft original. Which makes me wonder why sell these clips when so far as I can tell they don't fit any hose but the original ?

Which fuel hose does a UKC3794 clip fit ?
Is original dimension fuel hose available ?.... or am I missing something ?

sam christie

What part numbers? If you purchase generic stuff you just need the correct internal diameter and fuel grade and specify how much you want. If you order from MG parts suppliers you would specify what component(s) you wanted, which depends on the year and should get the correct bore and length, plus any fittings like the threaded connection for cars with HS carbs. For HIF carbs I'm pretty sure it is just a length from the metal pipe to the filter, another from the filter to the front carb, and another between the carbs, even the original Parts Catalogue specified 'as required' for some at least of these. The plastic filters usually have dual-diameter spigots so get the correct diameter for your fuel pipe and carbs. For the rubber bumper (I'm assuming this as you do say HIFs, but always tell us the year) MGOC quotes 5/16" for the first and 1/4" for the other two http://www.mgocspares.co.uk/acatalog/MGOC_Spares_LINES___HOSES__MGB__27.html. 8mm is slightly bigger than 5/16" so is too big for the carbs.
Paul Hunt

Thanks Paul I take yor point that the hoses on the HIF carbs are served by (1/4") 37H7615M cut to size as required and the blue UKC3794 clips will fit this. I missed this point and stand corrected. Sorry if my tone was a little exasperated and unfair.In fact I did not understand that the SU HIF carburettors used a different diameter hose.

It is the 5/16" fuel hose I cannot find the original outer dimension despite quoting model year etc. Or can I ?

Thanks for making the point that the hose used on the HIF carburettors is 1/4" (mine has green clips). On my car the blue clips were fitted where the 5/15" flexible hose either side of the fuel filter is secured to the metal pipes.The fuel pipe on my car on the carb side of the filter is flared to 5/16" and then reduces to 1/4" as it heads to the carbs. It is the 5/16" hose which has perished but strangely the 1/4" seems perfect.

I bought my car in 1980 and it has done only a few hundred miles since. I still know the first owner and I am quite sure the fittings are all as from the factory.

But even at the time there were probably variations.



sam christie

"But even at the time there were probably variations."

Indeed so, strikes at suppliers and competion for the lowest supplier price being what they were, as well as Abingdon having to use what BL specified in many cases.
Paul Hunt

Don't forget to replace the fuel hoses from around the fuel tank and pump.

BOB
RES Schultz

Sam,
Take your perished hoses to the nearest hose specialist - they will offer you very high quality hose and clips at reasonable cost. The fitted result will be industrial standard which you can forget.
Roger

Thanks Roger, I took your advice and went to a local supplier. The quality seems to be better than the original but the modern hose all seemed to be thicker.It looks like I will have more luck with the 1/4" hose (I decided to renew it)which seems to be more readily available with close to original dimensions and I will be able to use the original clips.
sam christie

I also encase the hose running from the filter on the fender wall to the 1st HIF in flexible plastic wiring conduit (the corregated type with a slit)...I heard a fellow developed a slight crack on the hose and the fuel sprayed on the manifold and boom!...My feeling in such an unlikely event, the fuel would pool in the conduit and drip at the low point bend near the fender well, away from the hot manifold...As for the hose between the carbs, oh well...
Pete

I wonder if my understanding of fuel hoses has suddenly improved....

As I mentioned I wanted to use hose resembling the original but I found the new 1/4" and 5/16" hoses which I bought both looked bigger than the originals. But if the new hose was marked as the apparently correct size (good quality British Standard for unleaded fuel) I assumed I would have to accept a thicker hose.I used the supplier's recommended fuel clips which were clearly marked as being of the correct size.

Both hose sizes seemed a very easy fit (too easy)while the originals had been a very tight fit.I ordered and used the appropriate size of fuel clips. When I tested my new fuel pump I was disappointed to discover that fuel was seeping from the places where the new hose was connected.

Where had I gone wrong?

By way of experiment I tried the 1/4" hose on the 5/16" connections and though it was a squeeze it was very much like the fit and feel of the original hose and it looked like the original too.

I ordered and tried the next size down from 1/4" on the carbs and found the fit tight but no great problem and it felt like the fit original hose. It looked right too.I am much more optimistic about a good seal.

I appear to have resolved my problem but since this is a safety issue I am left confused. Have I just discovered what everyone else already knew ? Or am I going wrong somehow?



sam christie

I can't help thinking you have got far more deeply involved in this than ever you needed to. One of the main points of using clamps is that the hose can be an easy fit onto the pipe, the clamp seals it.
Paul Hunt

I believe that you were supplied with fuel injection hose. It is a bit larger in diameter due to the fact that it has to handle 45+ P.S.I. RAY
rjm RAY

What I don't understand is that the original hoses (factory fitted) were a tight fit and I could only achieve a similar fit using very slightly undersize hoses. I tried tightening the correct size clips/clamps to stop the seepage (not a drip - just a damp patch) but it felt like overtightening and it did not appear to work.

I suppose the scientific approach would be to measure sample cross sections of the original factory fitted hoses. I will try this and report back.

sam christie

I have a set of SUs in my shop on a complete 70 B engine. I know the hoses are original, however as noted in some posts, there were likely several choices over the years depending on the suppliers. The hoses are rubber with braided steel outer, but not stainless steel. They also have rubber end caps on the hose to control fraying of the braid and such. The clamps are what are often referred to as "type D". My curiosity was piqued and I found quite a selection of similar hoses made for Mini-Coopers at the following site, www.minisport.com (look under "fuel parts and caps"). It's an Australian company and appears to offer perfect replacements in specified lengths, with rubber end caps that might work for you. Mini Coopers ran SUs.
Rick Penland

This thread was discussed between 16/07/2009 and 09/09/2009

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