Thanks for your responses!

1200rallycar: Fair call, but I come from a reasonably mild climate in Newcastle (just north of Sydney…). I’ve recently moved to Melbourne though, so the problem may get worse!
I think I’ll look for the Hitachi or SU option. Depending on what I can source and prices of each. It will probably largely depend on availability of what inlet manifold I can source too. I’d prefer to buy new stuff when it comes to the carb, but I’ll certainly look at second hand for the manifold.

Thanks for the previous post too. I’m pretty confident I’ve eliminated the risk of air leaks through throttle shaft bushes. The primary shaft did have a small amount of play until I got it re bushed recently. There was no change to engine running after the rebuild, but it’s good to know everything is working as it should.

Benny: I hear what you’re saying about the idle jets. Similarly, I’ve tried increasing the float level to further richen the idle circuit. Not the best idea though as it messes all your circuits obviously. I mainly did it just to see if it made a difference. I’ve played around with a few idle jet sizes, but could probably try a larger one. I think I’ve had a 70 in the primary side before. They’re available up to 80 though if I’m not wrong. The only noticeable difference from memory was a poorer idle. I haven’t tried it again with the coolant hot box though, so might be worth a try again.

I recently fitted a new accelerator pump diaphragm and it’s working well. I’m thinking that the relatively large amount of non atomized fuel being delivered by the pump is potentially causing me the most grief, in that I’m not getting the full benefit of all the extra fuel from acc. Pump as it’s struggling to keep up with the air along the inlet runners as it makes its way to the engine. As I said, of all the things I’ve tried messing with as far as jetting/acc. Pump etc, the best improvement by far has been heating the inlet manifold. I’ll definitely try the larger idle jet again though now that I’ve got at least a little bit of heat in the manifold, so thanks for the idea!

Cheers,

Stu