Morgana Posted February 22 Report Share Posted February 22 I've not been able to get hold of Gower and Lee, and can otherwise find no reference to this part on the carburettor drawings. The pipe nut holding the fuel pipe into the carburettor was mashed on first getting the car, and didn't fit any metric or imperial spanners. After a weep where the only way to get it to stop was really mashing the nut, I need to redo the connection. It's an olive compression fitting, and since I find the olive can rotate on the pipe, which has flared out slightly beyond the olive, I guess this is the source of the poor seal. Flexolite for example have a 7/16" nut for 1/4" pipe, but with prior experience of unusual metric threads on the carburettor cover I think it's as well to seek further expertise... In passing, does anyone have concrete evidence that the carburettor's name is PSEI or PSE1? The Solex manuals are inconclusive as the sans serif typeface makes the numeral and the capital letter look identical! I'm tempted to think it's an 'i', since Gower and Lee who sell the parts have a PSEI-2, which would imply PSE2 if it were a numeral. Link to comment Share on other sites More sharing options...
Pete Lewis Posted February 22 Report Share Posted February 22 (edited) the 7/16 thread + 1//4" pipe sounds about right for the age i general there will not be any metric threads on uk solex carbs Pete Edited February 22 by Pete Lewis Link to comment Share on other sites More sharing options...
PeteH Posted February 23 Report Share Posted February 23 It is highly likely to be 1/4" BSP.?. Pete Link to comment Share on other sites More sharing options...
Morgana Posted February 26 Author Report Share Posted February 26 Thank you both. Pete L - I don't think I'll be sure of anything again after my experience with the M5x0.75 thread on the float chamber cover! 😁 PeteH - 1/4"BSP actually measures ~1/2" across as it comes from the bore size of steel pipe, and allows for threads to be made on the outside. In this case, the outside diameter of the thin-wall fuel pipe is 1/4" and the fitting will be made with an olive and a male tube/pipe nut. The examples I've seen for sale of this type of nut are UNF or metric. I have found a chap locally who has boxes of spares and is going to have a rootle for me. I'll see what he turns up... Link to comment Share on other sites More sharing options...
Colin Lindsay Posted February 26 Report Share Posted February 26 I repaired my threads with a 7/16 UNF tap, it worked fine and took the currently-available pipe fitting. The fuel pipe is 1/4, I had to make sure some I bought recently was not the current metric equivalent as there can be quite a difference leading to sealing problems. Link to comment Share on other sites More sharing options...
Morgana Posted March 20 Author Report Share Posted March 20 (edited) I got some nuts, olive and pipe in an order today. However, I think the nuts are for double flares rather than olives, as the ends are flat. Am I right in thinking they ought to have a conical inner surface to compress the olive successfully? Attached is a picture of the mashed nut off the carburettor (originality unknown, but with a flared inner surface) and the new one. I've not heard back from Gower & Lee to see if they have pipe nuts to match the carburettor. It's tricky as most of these fittings I've found are advertised as brake rather than fuel, so aren't made for olives. I understand olives are not suitable for brake lines as the pressures are too high, hence the flare fittings for those applications, and the alternative styles of 7/16-20 nuts... Edited March 20 by Morgana Link to comment Share on other sites More sharing options...
johny Posted March 20 Report Share Posted March 20 Is it the same as the pipe connection to the fuel pump on Spitfires and Heralds, item 60176? This is 1/2" x 20 UNF and I would have thought so - it comes in brass but is listed as also for brake pipes so probably doesnt have much of an inner cone. In the end you might have to drill your own cone to better suit the olive... Link to comment Share on other sites More sharing options...
Morgana Posted March 21 Author Report Share Posted March 21 (edited) It's similar - the fuel pump is 1/2"-20 UNF as you say, but the Solex is 7/16"-20 UNF on the same 1/4" pipe (which has been, as one might think, confusing). I haven't done work on the brakes enough to get to know the fittings, but I'm aware of the principle of flared ends. The original fuel pump I've got had steel pipe ends (so presumably original equipment) with olives on in the inlet and outlet. The original nuts are both some yellow metal and have a cone/chamfer on, with the new olives I have sitting into the nut by a small amount. I have seen some on eBay and other retailers that show pictures of the business end where it isn't flat, but often advertised as for brake pipes. I imagine it's a bit of suppliers not knowing, buyers not knowing and variation in the manufacture. From a purely mechanical causality perspective, it seems logical that the olive ought to be compressed from both sides. If a flat-sided nut is used, the edge of the olive will be pressed forward and the shaped recess in the carburettor will compress that end, but the other will not be suitably shaped. In extremis, I could machine a truncated cone of the right angle into the end of the nut, but for something sitting over the hot manifold it would be nice to get it right first time! The new one's a lot longer, too. I've not been able to find a part at Canley from the diagram, as their 'fuel' section stops at the pump inlet, and the carburettor doesn't have a piece of pipe associated with it. Aside, my pump to carburettor copper line is cable-tied to a mount at the front of the water pump, but from reading on here I understand it was originally rigidly mounted with one of the bolts for the pump to some sort of clip. The pipe I had to file the swage off in order to remove the useless olive and nut from is quite ropey, so I was considering replacing it with the cupro-nickel length I have just bought, but if doing that I may as well mount it robustly to the pump if that's where it's supposed to go. Edited March 21 by Morgana Link to comment Share on other sites More sharing options...
johny Posted March 21 Report Share Posted March 21 Be aware that the brake fittings are 3/8" UNF and look very similar to the new item in your photo but are obviously not the same as the bigger fuel pump component... Link to comment Share on other sites More sharing options...
johny Posted March 21 Report Share Posted March 21 Reckon you need one of these and it looks like its got as much of a cone for the olive as your old one... Link to comment Share on other sites More sharing options...
Morgana Posted March 21 Author Report Share Posted March 21 (edited) That does look similar, thanks for the Google-fu johny! The proportions look different from the one I have though (I've tried to make an equivalent perspective picture, attached), so I called Gower and Lee again but they only open Monday-Wednesday. I did get through to Canley Classics, and they say they don't do a B30 PSE1 kit because this nut is unobtainable! So perhaps there's more to it than meets the eye. I'll get one of the ones you show and do another comparison. Edited March 21 by Morgana Link to comment Share on other sites More sharing options...
johny Posted March 21 Report Share Posted March 21 If youre worried about the compressing the olive onto the pipe I think you could solder it instead. Then the fitting wont have to be pulled up so hard and sealing shouldnt be any problem as this is done by the olives front face and the pressure is minimal... Link to comment Share on other sites More sharing options...
Morgana Posted March 21 Author Report Share Posted March 21 That's not a bad idea. I think the olive on one of the spigots on the original fuel pump is soldered. I guess not something to do with petrol around! Would you align the end of the olive with the pipe, or have some projecting? Link to comment Share on other sites More sharing options...
johny Posted March 21 Report Share Posted March 21 A fraction protruding to get some solder on would be ideal - dont want to get it on the olive though👍 Link to comment Share on other sites More sharing options...
Colin Lindsay Posted March 22 Report Share Posted March 22 14 hours ago, Morgana said: That's not a bad idea. I think the olive on one of the spigots on the original fuel pump is soldered. I guess not something to do with petrol around! Would you align the end of the olive with the pipe, or have some projecting? If you're sure that the olive is in the correct position then solder it, but to a small length of pipe, about two inches. Then the pipe will rotate as tightened - can't do that with the original one-piece pipe! - and you can link the rest via a rubber joint. Link to comment Share on other sites More sharing options...
Morgana Posted March 23 Author Report Share Posted March 23 It's not 7/16" UNF at all. The thread profile is wrong and the 7/16" UNF nut that's just arrived doesn't fit. Left to right in the picture: original; 1/2" UNF from the fuel pump; new 7/16" UNF. Looking more closely, it's a very good fit for M12 fine. This is 1.25mm pitch, which is 20.3tpi - an easy confusion to make when expecting 1/2" or 7/16" UNF which are both 20tpi. This would also tally with the metric top cover screws in the bizarre M5x0.75 thread... Automec have a possibility which I will try next. Flexolite show a banjo fitting with M12x1.25 described as 'Solex Carburettor Thread' so I think I'm on the right track. Link to comment Share on other sites More sharing options...
Morgana Posted March 27 Author Report Share Posted March 27 (edited) Yes, new parts have arrived and M12 x 1.25 is the right thread for a Solex B30 PSE1. I have been fiddling with the new original fuel pump and a reproduction one. Interestingly, the original is drilled for 1/4" pipe (as expected for what's on the car) but the reproduction one is 3/16". This might be a problem as using 1/4" pipe with an olive, the pipe cannot be pushed far enough into the hole. The olive is right at the end of the pipe and in the couple of experiments I tried with new bits of 1/4" cupro-nickel pipe, compressing the fitting causes swaging of the pipe end to make a flange over the end of the olive. This is just the thing that has caused the fuel weep at the carburettor. With the stubs of steel pipe that were left in the original pump, the olive is some distance up the tube, with the part projecting beyond the olive sitting happily through the hole towards the body of the pump which avoids this problem. Edited March 27 by Morgana Link to comment Share on other sites More sharing options...
johny Posted March 27 Report Share Posted March 27 Good news on the fitting and I reckon the suppliers need to know👍 The pump is strange (3/16 is brake pipe size) and so to stop the swaging effect it sounds like you might have to solder the olive right on the end... Link to comment Share on other sites More sharing options...
Colin Lindsay Posted March 27 Report Share Posted March 27 54 minutes ago, Morgana said: Yes, new parts have arrived and M12 x 1.25 is the right thread for a Solex B30 PSE1. Strange, as metric would not have been used when those carbs were fitted new. All of mine take the original 7/16 and I've bought a few screw-in fittings from Paddocks within the last year, that fitted first time. This is where the olive sits on mine, new screw-fitting also on the pipe: Link to comment Share on other sites More sharing options...
johny Posted March 27 Report Share Posted March 27 10 minutes ago, Colin Lindsay said: Strange, as metric would not have been used when those carbs were fitted new. Weren't Solex European or something so might have used metric? Link to comment Share on other sites More sharing options...
Morgana Posted March 27 Author Report Share Posted March 27 (edited) The new (original era AC) pump is fine - it was when comparing the two I noticed the hole through the fitting into the body of the pump in the reproduction one is smaller than on the original. I've been given a new (old) pump by a local enthusiast with innumerable cars and a biplane in his wonderful workshop, as I wanted to solve the excessive spring pressure (and hopefully the oil leak around the fuel pump) once and for all. I've got a few different springs so I can see if the reproduction models can be improved with stock parts, and am making up the pipes to fit them before pressure testing. I'll try drilling out the holes in the reproduction one to 1/4" and compare. The car came with another reproduction so with the one off the car I have two to fiddle with. The new ones' springs are wildly different from the AC pump. Yes, Solex was a French concern which started in radiators before making carburettors after buying some French patents. I can only assume the designs were originally metric by nationality, and production in France only ended in 1988. The quest I had with the top cover screws shows metric is not alien (even if weird metric) to this carburettor at least, but it is interesting they seem to have made a UNF version as Colin Lindsay has. On mine the 7/16" is really sloppy though it will do up as they're almost the same TPI. The fuel pump's 1/2"-20 won't fit at all and M12x1.25 is ideal. Canley did say that this nut was not obtainable and that was why they didn't supply the fuel pipe from pump to carburettor for the 1200, so perhaps they've had the same confusing problem. Maybe it's one of those things the dogged and time-rich enthusiast can dig up that the professional cannot justify the time on. I bought all three parts Automec sell as M12x1.25, including one described as a 'Citroën carburettor' nut which looks like the original unrelieved fuel pump nuts apart from the different thread, so I'm going to try it first. They used Solexes so that fits, too. Alternatively, there is a UK and a European version of this carburettor, and at some point in the past it's been changed for reasons unknown! Though, as the previous nut threads on, despite being chewed on the head, it must have been with the carburettor and the fuel pipe been added at the same time, unless the end was not swaged and the olive could be removed. The whole assembly is cable-tied to a bracket near the water pump rather than being clipped as I believe it ought to be, so something's been done with it. That olive looks like the original ones on the steel stub pipes that were on my original pump. The new ones I have are shaped like a conical bifrustum rather than a barrel. In the reproduction fuel pump, that length of pipe cannot project as the fitting hole narrows too much, but that's how they're fitted on the original pump. The devil is in the detail, and in the archaeology! Edited March 27 by Morgana Link to comment Share on other sites More sharing options...
Colin Lindsay Posted March 28 Report Share Posted March 28 23 hours ago, johny said: Weren't Solex European or something so might have used metric? They were used on all sorts of cars of the period, a quick search of 'Solex' on Ebay gives an amazing range of cars - VW, Landrover, Jaguar and Renault for example. I do reckon however that the fuel connector was Imperial for the earlier British cars and Metric for the continental, but this changed later in production and I'd guess that by the mid to late 1970s they were all Metric. It stands to reason that the top cover can be changed, as in many cases the body is more or less the same across a number of models, and there were a number of cars that continued to use the basic carb years after the Herald was gone. As Morgana has done I'd use the metric nut with metric olive and pipe for the best seal, and on my own cars it's all Imperial as the two never really mix and match 100%. Link to comment Share on other sites More sharing options...
Morgana Posted March 28 Author Report Share Posted March 28 (edited) My whole carburettor must be metric: the top cover only has the holes for the screws to go through and the female fuel pipe tube nut thread, and it's the bottom half that has the tapped holes for the M5x0.75 cover screws. The olive recess appears correct (I don't know if metric olives are made with different angles, like SAE and DIN flares), and the M12x1.25 nut is made for 1/4" pipe so I'll put the whole thing together with what I have and check for leaks. Assuming a metric nut was supplied with the carburettor when delivered new, it's not too great a leap to think it was all made for imperial pipe and fittings, but they saved machining costs by keeping the same metric internal thread for all models. Perhaps as you say it was a later alteration, so my carburettor could be a later addition. The other end of the pipe is the fuel pump's 1/2"UNF. A friend's coming over tomorrow with a flaring tool so I can make some hose-retaining bubbles on the relevant bits of pipe - yes, I'll be on the lookout for the rubber slivers! Then I'll report back. Edited March 28 by Morgana Link to comment Share on other sites More sharing options...
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