Received yet another book, the Haynes manual on Japanese vehicle carbs. Quickly flipped it open, only to find out that it didn't deal with pre '80 vehicles :/ Fortunately I can return it.
I spent a lot of time looking for info on Hitachi SU-style carbs. I also took the time to study the pic of my carbs and found out that I have the dreaded "flat tops" (referring to the flat shape of the air valve suction (bell) chamber)! Flat tops were designed to accommodate the stringent anti-pollution laws introduced in the 1970s, not for performance or driveability. Typically, these later carbs were difficult to tune, caused hard starting, flooding, vapour locking, and poor low-end power. All of these problems can be resolved by installing earlier round tops.
According to the not so holy Haynes Datsun 240Z repair manual, "Later 240Z models (with or without emission control systems) are fitted with twin SU side draught carburettors made under licence by Hitachi (type HJG46W)." These HJG46W's are round tops but according to other sources, later 240Z models are definitely not equipped with those.
Fortunately, a few shops offer refurbished sets of round tops that can be bolted on without any probs. However, these shops work on exchange basis. Meaning that you hand in your old round tops in return for the refurbished set. But since you haven't got those in the first place, you need to hunting for an old set, or pay a core charge IF they offer that possibility. Paltech Micropolishing LLC however, does one better. They actually offer conversion from flat top to round top carbs, built like the non-US setups. You have the choice of keeping the emissions equipment or use an early intake without any emissions equipment if you don't need to pass emissions tests. I asked them a few questions and will most probably go with this option.
Oh yes, last night I won the bid on a faux wood wheel from a 1971 240Z. Can't believe I won it for $13.50 :) However, seller still hasn't reacted on my two messages so I figure the plonker ain't too happy nor willing to sell it. Hey, his fault by not specifying a reserve. We wants it!
