SU Carburettor

[Chris Sealy]

I've restored around thirty Solex carbs over the last ten years or so. Mostly AHD/G 30's for vintage cars, and half a dozen AHD 26's; three of which are currently adorning my fellow members Mk1's
Provided that they aren't corroded; they can almost always be restored to, as new, performance.
They work better than an Amal, because the near constant vacuum of a four cylinder engine causes accelerated wear of the slide and body, which can lead to jamming of the slide. An unpleasant experience, so I am told.
The only real peculiarity the Solex has, is to make the engine 'surge' a little, if the throttle is opened and then rapidly closed, causing a momentary rich mixture.
The main Solex problems are stripped threads, a worn float chamber needle valve; and as Paul says, a worn throttle spindle.
The worn needle valve causes either, no fuel to get through, or way too much. A worn spindle causes a generally weak mixture, leading to an engine that already runs too hot, to run even hotter. I've seen cylinder heads where the valve guides have dropped down. It also causes erratic idling.
I use stainless steel inserts to repair the threads. The needle valve can be disassembled and cleaned up in a lathe.
The throttle spindle is a little more complex, because some wear is of the spindle, and some of the hole that it rotates in. Ideally side play should be zero.
Bushes are available, but they only fix half of the wear. My preferred fix is to machine a groove near to both ends of the spindle and fit Viton O-rings.
This seals the spindle against air ingress and centres it in the pivot hole near enough for correct operation. This has to be done carefully by trial and error, so that the spindle is neither too tight nor too loose. I also add a bit of silicone grease to reduce wear of the O-rings.
I have a few spare parts, including floats, refurbished needle valves, and throttle body assemblies, fitted with Viton O-rings available for members only.
Cheers, Chris.

[will_curry]

Chris,

PM sent.

Will.

[KenM]

Thanks guys. I'll give the Solex a go