Ol' Rusty - FB/EK Sedan

[Errol62]

Went back and read your Carby overhaul. Spot on. I was lucky to find three good ones that didn’t need bushes. Amazing focus you’ve got mate!


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[funkyscooter]

Thanks Clay.
Worth mentioning that I have rebuilt the carbs and replaced the OA7 needles with SW needles. Why? Did a bunch of reading in my SU handbook where I found all the fixed HS6 needles that were used on cars where the capacity per carb was at least 1000cc. I then scraped all the data from https://sucarb.co.uk/technical/needle-comparison which is an online spreadsheet of SU needle data, imported data into excel and made a few hypothetical scenarios and assumptions to come up with this chart of the most likely fixed needles to work as a starting point on a triple carb 1 3/4 HS6, 202 red with a mild cam.

Screenshot 2025-11-23 at 10.28.53 AM.png (145.24 KiB) Viewed 61 times

Should have purchased a range of needles (new OA7 or KU, KO for a leaner profile at lower revs) , but at $66 for a set of 3, that could start to get a bit pricey, so went for the needle that is used as the Rich option on a twin carb 2138cc Triumph TR4.
The richness down low on the SW was a bit off putting, but I did some internet research on lumpy cams which suggested a richer needle at low revs is preferred due to overlap.
It is at this point that I can confidently say I know nuffin bout nuffin when it comes to engines and cams, so worse case the old OA7's can go back on if these SW needles don't work. Or I can have a crack at re-profiling them. But that is all a long way off - need to rebuild the engine first.

[Errol62]

I went with recommendations from a guy I know on the GMH Torana forum and afr dyno-ed flat 12.5 800-6000rpm wot. I think needles are TW. Red springs. ATF damping.


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[funkyscooter]

You discussion on the Torrie forum was part of my research . In the graph I have included the TW. 12.5 seems like a good result.
Went RED springs too for the dampers. Also ended up mixing and matching the piston dampers till I got them all in the recommended 5-7sec window for the piston drop test.