Tipidave

So here’s the thing... After driving the car into work yesterday with a cheesy smile on my face i thought that i would do the same today. Unfortunately before i could leave the car park this afternoon the car spluttered to a halt. upon investigation the carb bowl was empty.... after some very high tech investigation involving blowing back down the fuel line and listening for bubbles in the tank... the fuel pump came out and upon inspection has well and truly failed. The t piece on the end of the spindle is narrower than the fork in the lever end and so it will not be held in place. The two sides of the fork are separate and. Able to flobble around enough that it cannot be made good. i deliberately avoided buying a cheap Chinese copy and purchased from what i thought to be a reputable dealer. I was re-assured when i was told ‘we have sold hundreds of these and never get returns’. Was i just unfortunate? I think not!

I will put that in my list of things to do with the fuel system. I have to say that I do not like playing with the petrol supply... so once I am happy I do not intend to continue fiddling! Another good run today and no sign of any leaking fuel on shut down.

I am hopeful that if I can get a good old unit then I will be able to make good in the pump department. I have some 1/4 inch copper fuel pipe and if I can work out how to bend it think I will make a run of it between pump and filter....leaving only a short run of flexible from filter to carb. just back from a good run and have to say it is driving very smoothly. Waiting for distributor to come back now... sure that the repro one is no where near correct!

Time for a bit of an update maybe? I fitted the vacuum take off carb spacer that Colin pointed out on eBay. Works at treat. After a little fettling, with both carb and timing the vacuum at idle has risen from a steady 19 in hg to just under 21 in hg. And is steady.:) I have fitted a new fuel pump from supplied by James paddock. Before fitting i checked the output on the old one and it was 9.5 psi 🙂 The new one is still a tad on the high side at 4psi and fitted directly to the carb it was too much for the float valve ... so i have left the filter king in line adjusted to 1.5 psi. Initial results are that this has solved the problem of fuel leaking after stopping the engine. My guess is that as an earlier contributor suggested, the fuel pump pressure on the input side of the filter was bleeding through after turning the engine off. Mick Dolphin is going to send me an original pump which hopefully will solve the issue once and for all with a rebuild kit and original spring. But for now... off i went up the road, only to find that the main jet was now partially obstructed. In all i have cleaned out the carb three times. Seems to be ok now but wondering when the new ethanol proof fuel line will arrive. Pete you were damn right about those pesky slivers of rubber! Or more like little crumbs. Is there an opinion on whether this issue is likely to re-occur randomly... or once clear does it tend to stay clear if nothing is disturbed? Thanks for all the help so far... getting somewhere now

Ha yes... initially it will need to be instead. I do not have long enough studs and imagine it would end up interfering with the bonnet if it keeps going up!!

Fab. I have just made a purchase. I didn’t know that existed

Could i take out the drain tube from the manifold and try to tap a vacuum gauge there? ot could i take off the vacuum advance feed on bottom of carb?

Today. I have learned some more. Firstly, after my long run at the weekend, and following use of a colourtune plug today i have determined that the mixture is running rich both at idle and at higher revs. My neighbour also watched me off up the road and said there was a small black puff from the exhaust as i accelerated away and changed from first to second. Also when half way through my 150 mile trip at the weekend i stopped and inspected number 4 plug and whilst not the worst i have seen it was definitely a bit sooty, rather than a nutty brown. This was after 90 miles of relatively high speed (i use the term loosely)running. given the limited number of adjustments available... does this support the notion that the level in the float is high? or could a timing/ spark issue give the same? anything else? Valve adjustments re checked and found to be spot on.

Thanks for that... I have ordered a new pump and fuel pipe kit. Will try to set everything back to standard.

My connection from copper pipe to flexible hose is now leaking... so I will need to sort that out first 😳

If I need to buy an original fuel pump, some olives and new copper pipe... where would you get them from?

Yes I will do this. I will try my shim under the float valve first. next I may try to clamp the fuel out from the regulator and see if it still happens. finally I will see if I can get an original mechanical fuel pump band a new run of copper fuel pipe. thanks for the ideas... keep em coming 😀👍

I shall work it out... it will be a process of trial and error... as a friend of mine tells me.. something will happen .... something always does 👍👍😀

Ta muchly ... I am optimistic that in the right path now! Any info is useful 😀😀👍

I may be into the right track... it seems that today’s fuel is a significantly different specific gravity which results in the float floating higher in the fuel... which in turn raises the level of fuel in the float chamber. therefore I plan to put an additional washer under the valve to lower the fuel level a bit and see if it has an effect. Does this sound like a sensible idea??

Out of interest... is there any way to know that the float valve is seated at the correct height? Can it be measured relative to the edge of the carb body/lid? I have read about the need for different washers depending upon whether it is a plastic or brass float. In my case it is a plastic float. if the specific gravity of a modern fuel is sufficiently different from the old stuff... could the weight of the float now be incorrect? just a thought. I have now read severalrelated threads online, unfortunately none have reported a solution to the problem. Most just agree it is a problem associated with new fuels. with this in mind i filled up with the essohigh performance petrol which according to the essay web site does not contain any ethanol. thouughts?

Yes tank is venting ... not sure about the pump. I will try to get a decent photo of it. I know it isn’t the original and irritatingly I cannot find it in my ‘bitsa’ box... but the pressure regulator in the filter is adjusted and working. there is no evidence of it dripping fuel while the engine is running... only starts a few minutes after cutting motor. I am pretty sure that this isn’t heat related because I have seen it do it even when engine is still cold/cool even after a long run today it was pretty cool to the touch. Is there any way for fuel from the accelerator pump circuit to disperse into the swan neck... I did witness this although some was also coming from the bridge.

Thanks for the distributor info Colin

I have just returned from an impromptu 150 mile trip. The car drives pretty well and fuel economy is much improved (around 45 per gallon now). Acceleration is still a bit lacking .... Contact gap set 0.015” giving 39 degrees dwell angle and valve clearances all adjusted. Set to 15 degrees advance at around 700 rpm with vacuum removed and blanked. Two remaining problems with the carb are... 1) drip of fuel from spindle under the float chamber even when. It isn’t more than warm. One drip every 10-20 seconds starts about 3-5 minutes after stopping engine. Some fuel draining from the manifold drain too. This stops after around 20 minutes or so. I did try leaving the stopped car with the choke out in the hope that this would open the throttle butterfly sufficiently to allow any fuel in the throat to drain through the manifold drain. I am puzzled as to the cause. But most concerned about the drip of fuel onto a hot manifold. 2)Throttle mechanism reluctant to return spindle to idle position so idle revs appear high (around 11-1300 at a gues). A quick blip on the throttle and it will usually then settle onto the idle stop. Definitely improved from yesterday!

Well... I started to get a problem with percolation and also leaking from the paper top gasket ... having changed the fuel pump. At the time I didn’t really equate the two events. After a refurb, the carb still had a problem. I didnt really have a reliable way of testing the pressure, but a friend said that the super king adjustable filter was a good product and that is what I went with. Whilst the car wasn’t in my ownership the carb was swapped to a Weber which I think was always running a bit rich and the accelerator mechanism was a bit of a botch... hence my interest to return it to ‘standard’. I have just done a really good run of 90 miles and it ran well enough... a bit lacking in the acceleration department ... I will have a tinker with the advance when I get home. Again, I think the dizzy is not original and I have no idea about the curve. I have purchased an old original and intend to send to distributor doctor when enough pennies are put by. 😀😀👍

Well you may be into something there. It isn’t an original pump. However for that reason I put an adjustable filter king in line with just a short run of hose to the carb. As original stated I used a pressure gauge to set output to in between 1.5 and 2 psi. I am going back out to regroup and see if I can find anything amiss. Will take some photos. the frustrating thing is that it is almost there! Happy with electrics... the percolation issue can be tackled in time... I will drive again and see if I can glean anymore info. I think the revs were dropping( stuttering) when under acceleration pulling away. thanks for continued help 😀😀👍

Roger that. Will take the advice 👍👍

Ha yes... I am now well catered for but I imagine they will only get more scarce as the years roll by. 👍

By floating blockage do you meant the float chamber ? I did set the fuel pressure on the lower side of the range given, and of course the pressure gauge that I have could well not be calibrated correctly especially at the low end of the scale. Maybe tweak it up closer to 2 and a bit psi indicated? I agree it is all pretty simple really, however as with the electrics too... everything has to be just so. I think that I might order some new flexible fuel pipe, because although that I am using was meant to be ethanol proof I do wonder if it is giving rise to odd floaters in the carb. in the meantime I am also cleaning up an alternative carb that I have been keeping for a just in case day. 😂😂👍 kitchen smells nice

I didn’t dismantle the accelerator pump yet on the basis that this has nothing to do with the idle circuit and when operated is observed to provide a good squirt from the swan neck.