Colin Lindsay Posted March 16, 2020 Report Share Posted March 16, 2020 My Mk1 GT6 has the original pipe that it came with; I'm presuming a PO-fitted version in a single length of copper pipe all the way to the fuel filter just short of the pump. Having observed a slight kink in it I trimmed about three inches off the extra length at the filter end, only to find it was now too short at the tank end... I think that where I have followed the chassis contours rigidly, the PO went straight across curves etc so this would have resulted in it being slightly short when properly routed and there used to be a large curve below the fuel tank which I have now corrected, albeit drastically... I have two options: refit a complete length of original pipe, which I think is unobtainable (unless of course you know better, is it 1/4 inch?) or else inset a piece of Gates ethanol-resistant fuel pipe along the length, probably about four to six inches worth which will give me the length I require. I think from the WSM that this was done originally, but don't know exactly where - was it a requirement for the middle outrigger section to prevent metal-to-metal contact? I just want to confirm that this is street- and more importantly MOT-legal before I cut yet more bits off the pipe... is there a legal limit for a length of rubber fuel hose? I think I really just need reassurance that I'm not going to go up in flames once the car goes back on the road... Link to comment Share on other sites More sharing options...
NonMember Posted March 16, 2020 Report Share Posted March 16, 2020 OK, so first, 1/4" copper (or cunifer) pipe is readily available from specialists, though you do have to be careful because 6mm is a standard microbore that's extremely widely available but won't do the job. Naturally, I have some of both. The original would have been steel, of course. I believe I bought the 1/4" stuff as a kit for my Spitfire from a trader at Stoneleigh a few years back. If you do decide to go for "cut and shut", I've certainly had MOT men object to significant lengths of rubber fuel hose under the car, but I reckon four inches would be fine. The car that had rubber from the front outrigger all the way to the pump (at least 6") never got queried. 1 Link to comment Share on other sites More sharing options...
dougbgt6 Posted March 16, 2020 Report Share Posted March 16, 2020 Colin, My mk3 fuel line has a rubber joint in the passenger side rear wheel arch on the side of the chassis, it's supposed to be there, it has a part number. It's only a couple of inches long, but I see no reason it shouldn't be longer. Doug 1 Link to comment Share on other sites More sharing options...
Colin Lindsay Posted March 16, 2020 Author Report Share Posted March 16, 2020 Thanks guys, as usual I'm just thinking out loud and to be honest the rubber pipe wouldn't be more than about four inches; allowing for the pipe inserted inside there'd be about two inches of rubber alone. Rob's right about the metric stuff; it's imperial I need and don't want some modern approximation that won't suit either olives or pipe ends. The GT6 WSM fuel line shows a rubber joint on the Mk2, but not on the Mk1 - see photo, item 24 - so I'm assuming a short length won't cause any problems, although I'd rather use one continuous length if I can get some. Edited - just went ahead and bought a roll of 25ft by 1/4; might as well do a proper job for peace of mind, even if the other options are safe enough. Paranoid as usual, me. 1 Link to comment Share on other sites More sharing options...
Adrian Posted March 17, 2020 Report Share Posted March 17, 2020 When I was doing my mini the original fuel pipe as can be seen in the picture ran under the subframe and linked with a good 12-18" of hose. This location was was clearly unacceptable but had gotten through many MOT's previously. A new pipe purchased was long enough to allow it to bend above the subframe and 4-6" of hose used to connect to the tank outlet. I really don't think the presence of hose is a problem but the location where it is used (I would say especially on the smooth underside where it could potentially catch on any debris) is. My GT6 MK3 is solid all the way to the engine bay. Link to comment Share on other sites More sharing options...
Colin Lindsay Posted March 17, 2020 Author Report Share Posted March 17, 2020 16 minutes ago, Adrian said: When I was doing my mini the original fuel pipe as can be seen in the picture ran under the subframe and linked with a good 12-18" of hose. That was just an idle thought when I was posting, so I thought I'd ask - is there a legal maximum length of hose ie could the entire hose be of rubber if you so desired? A join, where the pipe runs through the centre outrigger, may be of benefit but I'll just sheath the pipe in rubber at this point to prevent chafing. I haven't been in a Mini in an age - my last one, sold in 1982, cost me £900, was found to be two cars welded together, and went off for trade-in with the driver's door held closed by a length of rope tied to the passenger door... Link to comment Share on other sites More sharing options...
Ian Faulds Posted March 17, 2020 Report Share Posted March 17, 2020 I'm pretty sure gt6 (mk3 anyway) fuel line is 5/16 dia. I bought a roll about 3 years ago. It narrows down to 1/4 at the engine bay.. Someone will know for sure on here Link to comment Share on other sites More sharing options...
Colin Lindsay Posted March 17, 2020 Author Report Share Posted March 17, 2020 Current eBay sellers are selling a full kit of both 5/16 and 1/4, which they claim is for all models, so that would seem to support your post. I'm not sure how accurate they are as the Spare Parts Catalogue just lists the pipe as 307537, no diameter given. None of my WSM give the diameter of the pipe, but am still looking. It's quite annoying at present that all I can find is supplied lengths of both sizes, but not one trader or site states what is actually required... so I don't know if I need to shell out on yet another roll of kunifer... what's the worst that can happen if I use only 1/4... Link to comment Share on other sites More sharing options...
NonMember Posted March 17, 2020 Report Share Posted March 17, 2020 I think the Mk1 had 1/4" all the way but the Mk2/3 used 5/16" for most of it. That certainly seems to have been true of the Vitesse. Link to comment Share on other sites More sharing options...
Colin Lindsay Posted March 17, 2020 Author Report Share Posted March 17, 2020 1 minute ago, NonMember said: I think the Mk1 had 1/4" all the way but the Mk2/3 used 5/16" for most of it. That certainly seems to have been true of the Vitesse. Had to run out to the garage and measure that; my calipers tell me the old pipe is 0.24 / 0.25 of an inch outer diameter. 1/4 will do, then! Link to comment Share on other sites More sharing options...
Ian Faulds Posted March 17, 2020 Report Share Posted March 17, 2020 We are talking fuel pipe not brake Colin. The fuel tank on my mk3 defo has 5/16 coming out of it. I guess the bigger dia coming down to smaller will give faster delivery to the carbs. You will probably get away with 1/4. Think spitfires will all be 1/4 Link to comment Share on other sites More sharing options...
Pete Lewis Posted March 17, 2020 Report Share Posted March 17, 2020 its a lot of flow to get a 6 pot pulling fuel down a 1/4" pipe (6,3mm) i would upto 5/16" (7,93mm) to maintain some horses pete Link to comment Share on other sites More sharing options...
Ian Faulds Posted March 17, 2020 Report Share Posted March 17, 2020 1 hour ago, Pete Lewis said: its a lot of flow to get a 6 pot pulling fuel down a 1/4" pipe (6,3mm) i would upto 5/16" (7,93mm) to maintain some horses pete There you go Pete will be right I'd use the bigger dia pipe. Link to comment Share on other sites More sharing options...
Colin Lindsay Posted March 17, 2020 Author Report Share Posted March 17, 2020 2 hours ago, Ian Faulds said: We are talking fuel pipe not brake Colin. Yes, I didn't mean brake calipers. They were digital Vernier calipers for measuring small amounts. If I fit a larger pipe Pete it may affect the union at the fuel tank, and I don't really want to waste another £30 on a 25ft roll of kunifer only to find that it won't fit the tank... and I have to source the correct unions and olives in a larger internal diameter. Link to comment Share on other sites More sharing options...
NonMember Posted March 17, 2020 Report Share Posted March 17, 2020 3 hours ago, Pete Lewis said: its a lot of flow to get a 6 pot pulling fuel down a 1/4" pipe (6,3mm) It's really not. The pump has a pretty good suck and will pull a fair bit more than the engine will use, as long as the pipe is clear. Link to comment Share on other sites More sharing options...
Dick Twitchen Posted March 17, 2020 Report Share Posted March 17, 2020 4 hours ago, NonMember said: I think the Mk1 had 1/4" all the way According to all my research when rebuilding UYA5G this is correct. 1 Link to comment Share on other sites More sharing options...
Pete Lewis Posted March 17, 2020 Report Share Posted March 17, 2020 if it was adequate i would assume triumph would have kept the lower cost 1/4 not upgrade a few pennies to 5/16 ?? for the later cars Pete Link to comment Share on other sites More sharing options...
dougbgt6 Posted March 17, 2020 Report Share Posted March 17, 2020 I replaced the rubber joint in the rear wheel arch after it disintegrated, (what a mess! what a smell!) the replacement went on easy to one pipe, but NOT the other. I dawned on me they were different diameters. Worryingly the smaller diameter was from the tank, the bigger to the pump. However, I've never had a fuel starvation problem before or since, so if it ain't broke, don't fix it. Doug Link to comment Share on other sites More sharing options...
Ian Faulds Posted March 17, 2020 Report Share Posted March 17, 2020 🤣 Vernier calipers I thought you'd gone nuts Colin but it's me ha ha 1 Link to comment Share on other sites More sharing options...
Colin Lindsay Posted March 17, 2020 Author Report Share Posted March 17, 2020 1 hour ago, dougbgt6 said: so if it ain't broke, don't fix it. Doug The GT6 has run very well for the last 20 years on the 1/4 inch pipe so that's what it's now getting. And it weren't broke, Doug, until I tried to fix it... Link to comment Share on other sites More sharing options...
NonMember Posted March 18, 2020 Report Share Posted March 18, 2020 13 hours ago, Pete Lewis said: if it was adequate i would assume triumph would have kept the lower cost 1/4 not upgrade a few pennies to 5/16 ?? for the later cars The 1/4" was fine for a Mk1, OK for a Mk2 2L, but not for a 2.5PI or TR5. Triumph commonised on 5/16" because it became the standard for the saloons. I think they even used it on 1500 Spitfires. 13 hours ago, dougbgt6 said: I dawned on me they were different diameters. Worryingly the smaller diameter was from the tank, the bigger to the pump. That's common. The tank was designed for the earlier 1/4" pipe. They could change the bulk of the pipe really easily and cheaply. Changing the tank would have cost. The same short stub of 1/4" at the tank, then 5/16" to the front, was used on Dolomites, including the Sprint. In fact, I rather suspect that's the only reason the later GT6s have that bit of rubber there. 2 Link to comment Share on other sites More sharing options...
dougbgt6 Posted March 18, 2020 Report Share Posted March 18, 2020 NM, I’ve wondered for a long time why that joint was there! Doug Link to comment Share on other sites More sharing options...
daverclasper Posted March 18, 2020 Report Share Posted March 18, 2020 (edited) On 17/03/2020 at 17:55, Dick Twitchen said: I think the Mk1 had 1/4" all the way I think so. The Mk2 Vit and MK3 Gt6 had the larger bore after the fuel pump. I always wondered if that the bit more powerful engine at high revs used bit more juice though maybe as Rob says, universalising the manufacturing. Edited March 18, 2020 by daverclasper Link to comment Share on other sites More sharing options...
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