Ported vacuum advance cd175

I am surprised that the carb v12 has vac retard and no vac advance.

Apparently this is (any of/ all?) for some emissions reason, to give a faster warm up or to smoothen the idle.

There are lots of variations in the actual system depending on the market. Here in oz, no emissions control was mandated until 76, yet the earlier cars still had the retard system

This must mean that part throttle timing is not ideal (advance only centrifugal).

Iā€™m interested in the idea of modifying one carb to give a ported vac (perhaps copying a range rover carb).

I note that there is a JLM520 vac canister that might give the best of both worlds - cruise advance and idle retard

any experience/ advice?

Rob Medynski is the guy you need to contact. He did my '72 E . It works great !

Rob converted/ported one of my carbs ā€“ after Joe Curto did his restore/refurbish/rebuild magic.
This is what I got back from Rob

Rob also restored/rebuilt my original dizzy and converted it to Vacuum Advance. It included a handwritten data sheet for fine tuning

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