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My Lomax, which appears to have a Solex 34 PICS carb (why didn't they stamp the model on it?) tends to stall on the throttle back / overrun, as if it were slightly starved of fuel during deceleration. A chap at the Kit Car Show suggested I removed the jet on the side of the float chamber, and took the bore out to 1.1 or 1.2mm. On looking at the carb now, there are two jets, the forward one being externally round, and the aft one a heaxagon. Can someone please advise which I should be tackling? Thanks, as ever, to the really helpful chaps on this forum. Patrick

hotfoothowell,
I have modified my standard carb by drilling hte jets, up one size.
There was an article in Flat Out No 69 regarding mods to the carb done by Keith Bulland Terry Wallis, that I followed and the effect was to loose the stagger on acceloration and backfires.
If you send me your email address I'll send a copy for your info.
My email...billdavies1@yahoo.com
regards Bill D

Thanks, Bill
My email address is hotfoothowell@hotmail.com
Patrick

Patrick,
check on the offside face of the float bowl, just below the top edge and you should find something along the lines of '34 PICS 2' punched into the metal.
Those 2 jets on the nearside are the idle jet (round head) and bypass jet ( hex head) and their drillings will be between 0.4mm and 0.5mm for the idle jet, 0.5mm to 0.55mm for the bypass jet.
Taking them out to 1.1mm or 1.2 mm is likely to throw the idle mixture so far out that it won't idle any more, so I'd suggest a less drastic move might be to take the idle jet out to 0.55mm as a first step.
The idle mixture screw, facing backwards towards the starter motor, will need adjustment afterwards, of course.

However, is it worth asking if you've already tried adjusting the idle mixture screw?
Find the best setting for a steady tickover, then richen it up a shade by turning the idle mixture screw out half a turn...

Ken

hotfoothowell wrote:My Lomax, which appears to have a Solex 34 PICS carb (why didn't they stamp the model on it?) tends to stall on the throttle back / overrun, as if it were slightly starved of fuel during deceleration. A chap at the Kit Car Show suggested I removed the jet on the side of the float chamber, and took the bore out to 1.1 or 1.2mm. On looking at the carb now, there are two jets, the forward one being externally round, and the aft one a heaxagon. Can someone please advise which I should be tackling? Thanks, as ever, to the really helpful chaps on this forum. Patrick

Ken
Thanks for that. My spare carb does indeed have 34 PICS 8 stamped on it, but the one fitted, which is very similar, but not identical, is marked 29K8 25 02 (if my fading eyesight can be trusted) , and does not have an idle mixture adjuster at the back. Can you suggest where to go from there? Patrick

Patrick,
seems very odd that Solex could have got away without fitting an idle mixture screw, unless the anti-tamper plasitc plug is still in place after all these years.
If it is, that can be levered out to give access to the adjusting screw hidden behind it.

Any chance of a photograph of your carburettor, taken from directly behind?

Ken

hotfoothowell wrote:Ken
Thanks for that. My spare carb does indeed have 34 PICS 8 stamped on it, but the one fitted, which is very similar, but not identical, is marked 29K8 25 02 (if my fading eyesight can be trusted) , and does not have an idle mixture adjuster at the back. Can you suggest where to go from there? Patrick

Hi Ken ,it was I that had a chat to Patrick at the Stoneme kit car show last sunday and what he said to me was that his car was suffering from almost stalling at junctions and generally was reluctant to pick up with popping and farting about. So I suggested the mod that you advised me about some years ago which cured similar probs on my car. I explained it in detail ,ie, drilling the horizotal jet in the right hand float chamber,even to
the point of how to get the jet out,how best to drill etcetera. But it seems as though he is somewhat confused as to what jets are what? He is in our Cotswold section and if he wanted to pay me a visit I would gladly help him. Hope things go well for you old friend ,regards ,Badger.

Hallo Gordon
Thanks for the time you spent advising at Stoneleigh. I suppose I should have taken you over to my car then, as when I got home, I realised that the jetting arrangement on my carb was a bit different from what you were describing.
Ken, I have tried to attach a photo, but the website says that it is too big for the 500kb limit. A bit surprised, as I have seen photos on site before, am I doing something wrong? Anyway, yes, there is a plastic plug behind and to the bottom of my carb, which is not yielding easily; presumably this is concealing the idle mixture screw, as you describe? But I am no nearer to discovering the exact model of Solex it is, and unwilling to dismantle until I know that, as Sod's Law then decrees that the gasket you haven't got is then broken!
Patrick

Patrick,
let's try using the photographs the other way round, with me posting one...


Solex 34 PICS 6 - choke return spring by slcchassis, on Flickr

This is the only one I can find at the moment for a Solex 34 and Sod's Law dictates that this isn't the same model as yours.
Is there what looks like a tube, 16mm long, projecting near the base of your carburettor, with a black plastic plug around 6mm in diameter blocking the end?
Once that plug is out, there's access to a slotted screw inside the tube, turn it outwards ( anti-clockwise) to enrich the idle mixture, but make any adjustments only when the engine is at running temperature.
If that doesn't cure the problem, next step would be to check that the accelerator pump is working correctly.
After that, check the main jet, a 165 seems to work best on these single barrel carbs, if I recall correctly.

Ken

hotfoothowell wrote:Hallo Gordon
Thanks for the time you spent advising at Stoneleigh. I suppose I should have taken you over to my car then, as when I got home, I realised that the jetting arrangement on my carb was a bit different from what you were describing.
Ken, I have tried to attach a photo, but the website says that it is too big for the 500kb limit. A bit surprised, as I have seen photos on site before, am I doing something wrong? Anyway, yes, there is a plastic plug behind and to the bottom of my carb, which is not yielding easily; presumably this is concealing the idle mixture screw, as you describe? But I am no nearer to discovering the exact model of Solex it is, and unwilling to dismantle until I know that, as Sod's Law then decrees that the gasket you haven't got is then broken!
Patrick

Ken
Thanks, I will look again; meantime, can you give me your email address, and I will attach a photo of the carb as fitted. Patrick