problem with P505, 32/35 tmima carburettor.
- Thread starter 2pac
- Start date
Has it a strong smell of petrol, or does it smell of something else? Being unhappy with constant speed is a classic symptom of a lean mixture, but that wouldn't go with a strong petrol smell. Lean mixtures also can give a smelly exhaust -- perhaps if we were both wine tasters we could communicate at that level ("strong turpentines with fish and chip shop colours and a burning rubber finish") -- but I'm not, so let's not.
Not sure what to make of the "valve" noise. Pinging can have a clattery sound which can be mistaken for valve rattle, but we've already done plenty on ignition timing.
Like Peter, I think it'd be helpful to have a better picture under various conditions. When is it ok, when does it play up. You've driven it round the yard. Does it seem to behave itself under a heavier load? If you try a standing start in second, does it work as it should, or miss and play up?
Have fun,
Rob.
Not sure what to make of the "valve" noise. Pinging can have a clattery sound which can be mistaken for valve rattle, but we've already done plenty on ignition timing.
Like Peter, I think it'd be helpful to have a better picture under various conditions. When is it ok, when does it play up. You've driven it round the yard. Does it seem to behave itself under a heavier load? If you try a standing start in second, does it work as it should, or miss and play up?
Have fun,
Rob.
That is what I would expect any engine to do. You have unburnt fuel being burnt. What driving condition do you do that ever has you travelling at 4000rpm then you drop down to idle or you take your foot off the accelerator pedal? If you drive your car down a hill turn the key off & then turn it back on again you will get an even bigger explosion from unburnt fuel. You are trying to fix a problem that doesn't exist. Drive the car and see if there are any problems then. Check the spark plugs afterwards to see if there is any fouling if you have problems
I reckon you'd know whether or not it's running correctly.
I still wonder if the fuel is lean. From your description it sounds like the engine is pinging which would mean that the timing is wrong or the mixture is too lean or possibly other causes. Google "pinging" or "pinking" for more info. If the car is driveable, go for a short run down the road and see what it does under load and at different speeds.
I still wonder if the fuel is lean. From your description it sounds like the engine is pinging which would mean that the timing is wrong or the mixture is too lean or possibly other causes. Google "pinging" or "pinking" for more info. If the car is driveable, go for a short run down the road and see what it does under load and at different speeds.
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problem found- it's the economiser. the ball valve doesn't sit tight in its hole, so fuel is flowing constantly from there into the engine. the hole probably wore out because i tried another valve and it's the same, while in another carby they sit very tight, so now the question is how to fix it...
Glad you have a diagnosis.
A long time since I've had a Solex apart but I take it the seat is the carburettor body itself. Perhaps a machinist could ream out the seat and machine up a new one in brass? Not 100% sure, but the ball part is probably an on/off switch, with the extra fuel actually going through a true jet to determine how much extra fuel the engine gets at low vacuum. So the machining of ball and seat is not all that critical.
Against that, if the fuel was properly metered later in the circuit, your car would have run pretty well -- just with poor economy. Running so badly suggests unmetered fuel getting in. No puncture in the diaphragm?
Have fun,
Rob.
A long time since I've had a Solex apart but I take it the seat is the carburettor body itself. Perhaps a machinist could ream out the seat and machine up a new one in brass? Not 100% sure, but the ball part is probably an on/off switch, with the extra fuel actually going through a true jet to determine how much extra fuel the engine gets at low vacuum. So the machining of ball and seat is not all that critical.
Against that, if the fuel was properly metered later in the circuit, your car would have run pretty well -- just with poor economy. Running so badly suggests unmetered fuel getting in. No puncture in the diaphragm?
Have fun,
Rob.
didn't quite understand you, because unmetered fuel getting in is just what happens now. the diaphragm is new, but a puncture in it would give the same result- unmetered fuel getting in.
the seat is the carb body, the valve is a ball and a spring inside a brass jet.
i'll just seal around the valve with Permatex No. 1 which resists gasoline. it's too delicate for a machinist job.
You're definitely in the best place to know what to do. Best place to do it too!
To explain what I meant, the point of the economiser circuit is to deliver extra fuel when vacuum is low (i.e. throttle opened up -- other carb. makers call it a power valve instead of economiser). This extra amount is metered through a jet -- the ball just turns this additional metered fuel on and off. It's not all that much extra fuel so I'm surprised it runs so poorly. That's more what you'd expect if truly unmetered fuel was getting in.
If there's a path around the valve that doesn't go through the jet then you're absolutely right. And the Permatex idea sounds like that's what you're seeing. So go ahead and don't mind me.
Hope it works well.
Have fun,
Rob.
To explain what I meant, the point of the economiser circuit is to deliver extra fuel when vacuum is low (i.e. throttle opened up -- other carb. makers call it a power valve instead of economiser). This extra amount is metered through a jet -- the ball just turns this additional metered fuel on and off. It's not all that much extra fuel so I'm surprised it runs so poorly. That's more what you'd expect if truly unmetered fuel was getting in.
If there's a path around the valve that doesn't go through the jet then you're absolutely right. And the Permatex idea sounds like that's what you're seeing. So go ahead and don't mind me.
Hope it works well.
Have fun,
Rob.
The idle jet which is a press fit in its holder needs to be partially pushed into the holder, when screwed into its 'ole the jet will seat correctly. If not seated fuel will by-pass causing rich running. No amount of idle mixture adjustment will reduce this.
in the TMIMA there are 2 idle jets which are screwed in, no press fit.
2pac,
Apologies, I can only blame the Christmas pudding. My post was directed mainly at the Weber carb fitting.
Apologies, I can only blame the Christmas pudding. My post was directed mainly at the Weber carb fitting.
If you don't think it's still running correctly, what are the symptoms?
I didn't fix it yet.
