[6pack] SU needle for TR6 Conversion?

[Tomislav Marincic]

I'm thinking of switching to SU carbs on my TR6. Moss sells the conversion kit with the BAG needle, presumably for the stock TR6 engine.

Has anyone played with the needles already and found a better one to start with for a TR6 with the usual mods? (9.5:1 CR, GP-2 cam, header/exhaust, flowed head, 1.65:1 RR)

As a reference, I've tried 4 needles in the ZS carbs:

B1E (jag) :pulled like crazy above 3k, totally undriveable around town (rich). Would not idle.
B1AQ (stag) better around town, still too rich. Lumpy, high idle.
B1AF (TR6) Nice consistent idle, too lean above 3k, pings from 2200-3000 at more than 1/2 throttle, no power above 4k

I'm currently running B2Y (TR250) needles that I converted to adjustable-type by using the needle housings from my B1AF's. The idle is good, the plugs are whitish-tan, but the car still pings 2200-3000 RPM unless I retard the timing, and the power above 4k is not what it should be for a modded engine. I know the engine is capable if much more.

I'm betting that SU's with adjustable jets would give me a greater range of adjustment and a wider selection of available needles. I'd also like to eliminate the variable of the temperature compensators on the ZS.

I'm sure some of you have been down this path? Any tips?

Cheers, Tom

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