Hesitant on initial throttle application

[nistri]

I agree with Tim's message: carbs are often blamed when the problem is somewhere else. Andrea

[andyps]

That is really helpful David, thanks.

I can't see fast idle jets from that eBay seller but will have a search and see if I can find them somewhere.

They have what ever you need. Just email them. They do a kit containing 8 jets - 4 of one size 4 of another. Suggest you order +5 and +7.5 to start. However as I said before real hesitation (a “hole”) is likely to be something else underlying.

I haven't had chance to try the cable tie measuring you suggested, hopefully will have a chance this week. The timing chain might take longer to investigate and sort.

[roddy]

I see an earlier post of mine from some years ago has been resurrected, and it is perhaps relevant to revise my views.  Richening the slow running jets did effect some sort of remedy at the time but it was not the proper solution. Almost by accident, when the carbs were off the engine, I noticed that there was quite a lot of 'play' in the butterfly spindle shafts in the their bushes. I did have a pair of overhauled Solexes on the shelf that had had new bushes and spindles fitted, and swapped them over.  Instantly the problem of faltering on pick-up was gone and I had to revert to the standard size of jets to avoid fouling plugs.  I can only surmise that the worn spindles/bushes were allowing air to enter the manifold that had not flowed through the venturi to pick up the requisite amount of fuel dispensed by the slow running jets. Once the butterflies were opened further and the main jets operating, the fuel/air ratio sorted itself out.

Hope of some interest / use?  Regards -

 

[lancialulu]

Andy

It seemed to go alright on  your video

https://www.youtube.com/watch?v=PY0LKThzh84

Tim

[andyps]

Andy

It seemed to go alright on  your video

https://www.youtube.com/watch?v=PY0LKThzh84

Tim

Thanks for watching my video. I understand what it does well enough now for me to be able to drive around it and it not be an issue, I'd just rather not have to do that! Once past that hesitation it does go well.

[andyps]

I see an earlier post of mine from some years ago has been resurrected, and it is perhaps relevant to revise my views.  Richening the slow running jets did effect some sort of remedy at the time but it was not the proper solution. Almost by accident, when the carbs were off the engine, I noticed that there was quite a lot of 'play' in the butterfly spindle shafts in the their bushes. I did have a pair of overhauled Solexes on the shelf that had had new bushes and spindles fitted, and swapped them over.  Instantly the problem of faltering on pick-up was gone and I had to revert to the standard size of jets to avoid fouling plugs.  I can only surmise that the worn spindles/bushes were allowing air to enter the manifold that had not flowed through the venturi to pick up the requisite amount of fuel dispensed by the slow running jets. Once the butterflies were opened further and the main jets operating, the fuel/air ratio sorted itself out.

Hope of some interest / use?  Regards -

Thanks Roddy, I did a rebuild of my carbs and couldn't detect play in the spindles but maybe should take them off again and check again.

[Spider2]

My carburation problems solved. All jets ultrasonically cleaned and I changed one float valve as it felt a bit “gritty” when pushed up.
The car now runs the best ever. It revs to eternity and back instead of running out at 5,000 rpm. I can really recommend investing in an ultrasonic cleaning tank. They are cheap and they work!

[Mikenoangelo]

Well done and thanks for the ultra sonic  tip.

Mike

[davidwheeler]

I see an earlier post of mine from some years ago has been resurrected, and it is perhaps relevant to revise my views.  Richening the slow running jets did effect some sort of remedy at the time but it was not the proper solution. Almost by accident, when the carbs were off the engine, I noticed that there was quite a lot of 'play' in the butterfly spindle shafts in the their bushes. I did have a pair of overhauled Solexes on the shelf that had had new bushes and spindles fitted, and swapped them over.  Instantly the problem of faltering on pick-up was gone and I had to revert to the standard size of jets to avoid fouling plugs.  I can only surmise that the worn spindles/bushes were allowing air to enter the manifold that had not flowed through the venturi to pick up the requisite amount of fuel dispensed by the slow running jets. Once the butterflies were opened further and the main jets operating, the fuel/air ratio sorted itself out.

Hope of some interest / use?  Regards -

 Interesting...    I had thought that my carbs were the ones I had had rebushed but perhaps they were in the other Fulvia.    The car is currently off the road with bodywork work so I shall have another look.     Ultrasonic cleaning also worth investigating.

[HenryTennant]

Hello All, Read this thread with interest. I have been chasing a flat spot between 1800-2000rpm on my S3 coupe, very late 1976 car. I have 55 slow running jets, which helped but not completely. Pertronix points and a higher output coil also helped.
But the following might be of interest. By the way my car is very low mileage, 18000 from new!
My carbs are Solex C35PHH E3 (the E3 stamped on the top cover). The standard jets for these (as confirmed in the car handbook) are Slow running 52, main jet 115 air corrector 180. I changed the 52 to 55 with some improvement as mentioned.
The slow running screws have M5 x 0.8 threads and a very fine point, more or less parallel 1mm for the last 4mm, not like the conical "biro" tip shown on the cross section drawings I have found for the C35PHH carbs. I'll try to add a photo.So I am thinking the tuning advice given in R C Pack's Brooklands Books manual may not apply i.e. unscrew these about 2 turns as a starting point. Mine are at 3 turns out now and I will try more.
Where does anyone else with the E3 carbs find they have to set them?
Then as to fuel level and emulsion tubes. As per a forum comment of a good few years ago, mine have the open ended tubes. 4 pairs of cross drillings, the top ones 20mm below the tube seating flange. The "tide line" fuel level is 17 mm below the flange - so above all the cross holes. Confirmed by the "cable tie" dipstick method. The tubes screw into brass bushes in the carb body, not directly into the alloy. The float arms have not been bent, and weigh 10gm.
So is this correct for fuel level? I have never seen a fuel level given in the Solex literature, only comments in the forum that it should be 19mm below the alloy body surface. If I take account of the brass bush thickness about 1.7mm mine would be 15.3mm. But this level must surely depend on the type of emulsion tube, so maybe all is correct on mine.
I'll add a few photos. Any comments would be very welcome, particularly on number of turns for the slow running screws. And for recommendations regarding good Solex books or manuals.
Henry.

[dhla40]

You are correct that most of the information and settings available refer to the earlier carbs. I have the E3 carbs on both my cars and use 55 idle jets on one and 57 on the other, the mixture screws are at least 4 turns out maybe more depending on any air leaks. I measured the emulsion tube inserts at 2mm so to check a fuel level of 19mm I make a bend in a bit of wire to leave a leg of 21mm to poke down the well  till it touches the fuel surface. I am experimenting with 125 main jets to try and improve a sensation of weakness during transition at 3000rpm, feels like an improvement and AFR is in the 13's but needs more road testing.

Sean

[nistri]

My experience is that E3 Solex carbs are troublesome and, if possible in terms of cost and availability, they should be replaced by earlier carbs. Andrea

[lancialulu]

for what it is worth I attach the data sheet for the C35PHHE 3. It does not show a brass shoulder for the emulsion tube housing but the data sheet could be wrong....

I agree with Andrea best solution is to change to earlier non emission solex's.

[dhla40]

The diagram is a generic version of the early carb just to show where the main components are. The E3 body has many differences, the idle jets feed from the well not the float chamber, the top cover has extra screws and return spring, the mixture screws have narrow taper, the pump membrane is bigger, there are vacuum ports and the idle bleeds are 2mm.  The emulsion tube inserts are compensated by a longer tube which lets the 19mm fuel level fall just below the top hole.

Sean

[HenryTennant]

Thanks for the above info everyone. Its very helpful to know what others have actually done.
I do not want to change the carbs, mine are in good condition and I'm sure worked well when the car was new.
I have been out for a test run today after resetting slow running to 3 1/2 turns out. It idles nicely, but sounds a bit rich at 4 turns, no increase or decrease in idle speed though, so I left them at 3 1/2. It goes well, pulls well through the offending range so I'm pleased and will leave it like that without doing anything else.
Does that mean you think the fuel level in mine is right or too high. The E3 spec sheet has 19mm so I suspect mine actually is too high.
Has anyone checked the weight of their floats? I may get a pair of new floats at some point.
Henry.