Lagondaforum

Subject: Solex Carbs verses SU

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Have managed to get the Solex Carbs to perform very well. Tickover is excellent as is the delivery of power. However, the left hand carb floods when descending log hills (of which there are many in Derbyshire) & subsequently dies sometimes. Has anyone experienced similar & could it be linked to vacuum?
If I wanted to go over to SU carbs is it possible & what would I need to do? Has anybody done twin or triple SU's on their car?

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Subject: Re: Solex Carbs verses SU

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Guy, records show that several Rapides have or had either a 2-SU or 3-SU set up, of the HD8 type as for a DB4 standard or vantage or DB5 standard engine, for example triples are in 118 (the Wills racer) and 128 in France or twins were in 152 before it fell apart. Interesting also that 146 which is owned by Works Service had 3 SU when they bought it but now has Solex. In the Aston set up the carbs had UN or UJ jets, but you might have to experiment with the Rapide because it has different (softer) cam profiles. And if you were to fit 3, you'd need to know that the float heights are different and not as per the workshop manual. I've had plenty of issues with the Solex on my car over the last 10 years, but mostly petrol leaks (usually from the front carb), not the symptoms you describe despite much touring in the Cambrian Hills etc. There are I fear not many people who really know how to diagnose faults with the Solex and to set them up correctly. When my car was fresh out of rebuild 10 years ago, it would not idle smoothly and lacked power, so Andy Chapman (who used to look after my cars when new at AML) set the carbs up properly, and it took him 6 hours including road testing etc, and even then he did not set up the choke mechanism, which I have actually found no need to use even in winter. And they have hardly needed adjustment since despite 10000 miles. So my view would be that there is a set-up problem or fault with your rear carb, rather than a design issue. I'm sorry but I don't have the knowledge to specify a vacuum problem; Christian who has personally rebuilt his car's carbs may be able to recall the theory of operation and offer diagnoses; we will I am sure be interested to learn from his experience of setting up the carbs on the engine once running. It also occurs to me to ask if there might be an unintended "issue" arising from your car's installation of the 4-speed gearbox and revised kick-down mechanism from GW Autos?

Subject: Re: Solex Carbs verses SU

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Sorry, I can't give any useful guidence as to why one of your 44's is flooding when going downhill. My knowlegde of these carbs is theoretical and I know how to rebuild them. I assume as you let you foot off the accelerator the carbs are not restricting the fuel flow adequately, the float chamber valve?

Personnally I would not change them to SU's as when working correctly I believe they are very reliable. I also think that they're one of the distinctive parts of the Rapide which set it apart from the rest.

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