SU fast idle adjuster

[Howard Wright]

Hi All

I’ve been playing around with an H series 1 1/4 SU and to avoid using a fuel pump and as suggested in an earlier thread (Solex 26FV) I have mounted it under the manifold in a semi updraft fashion. To do this I’ve swapped the float chamber and throttle levers to opposite sides of the carb body.  This leaves the float chamber level. The choke levers fit in their original position as there is no room to swap those over too.  Unfortunately this means that with the throttle lever on the “wrong” side the fast idle adjusting screw sits in mid air on the opposite side to the cam  .

How critical is the fast idle mechanism?  I plan to retain the steering wheel levers and it seems to me  that the “gas” lever does almost exactly what the fast idle mechanism does only manually?

I’d also welcome comments on whether I need a heat shield as the float chamber is quite close to the exhaust manifold.

Cheers

Howard

[bob46320]

I think you may have to have a hefty heat shield between float chamber and exhaust.

[Alan]

It looks like the fuel level is going to be too high. I think you will need to lower the float chamber. When I’ve used semi updraft SUs I’ve always contrived a little bracket to drop the attachment point by about an inch.

[Duncan Logan]

Definitely will need a heat shield. that carby is going to cop heat from all directions.

[Howard Wright]

Thanks all

Particularly Alan who pointed out that the float chamber was too high.  I’ve made a new long banjo bolt for the float chamber and will fit a 1” tubular spacer to make the float level about the same height as the top of the jet. I can adjust the height by changing the spacer once I get the car running. 

The lower float chamber also allows me to use of the fast idle mechanism  .  

I can make an aluminium shield and stick heat shield material on it.

Cheers

Howard

[Alan]

Howard, fuel level isn’t that critical to within 50 thou or so, but with the jet fully lowered by pulling the choke lever, the fuel should just cover the jet.

[Howard Wright]

Thanks Allan