Get rid of the Holley. They are shocking carbies, pretty much without exception. You can usually get them tuned well within about a 1,000rpm range, anything outside that they'll run like a dog. Good for sitting on top of a boat engine thats running flatout constantly, not much else.
At the very least, it sounds like the carb is massively too big for the engine anyways - Notice any streams of black smoke when you give it a boot down the road?
Like Gav said, go for an early set of 240 SU carbs if you can get them, else look for a pair (or even 3! :twisted: :twisted: :twisted: ) of mikunis/webers. Have a look on www.ozdat.com, there are normally a couple of sets of zed carbies with manifolds at any given time.
If you are really desperate, I have a pair of working Hitachi carbs with manifold sitting on the L26 I pulled out of my 260, but they aren't particularly fantastic either....
*QUICK BROWSE OF OZDAT*
"260Z manifold with Round top Pre Poll SU-Hitachi Carbs fitted $200, 240Z Carb set up Orig carbs with orig colour Red Air Box $600
bird_davidj@hotmail.com Dave 039802 5806
M 0400 343301
Location: Burwood Vic Vic
Contact: Dave Email: bird_davidj@hotmail.com
Phone: 039802 5806 "
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There you go - they've been up for a little while, both decent options - obviously the 240Z carbs would be preferable (Not least since they have an airbox which you'll probably need!) But the round SU copies should be fine too, I think - I can maybe supply an airbox for those, if you need it.
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"twin solex mikunis Twin 40mm solex carbs on redline manifold can test on running car $250.
Price: from $80 Location: daylesford Vic
Contact: lauree Phone: 0408 519746"
Manifold is for a 1600, but the carbies should be okay on a stock L26 - my alfa was a 2 litre that run rich on twin 40mm dellortos (stock).