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I remember reading somewhere that the L series engines did not run so well on down draft carbs. Yes many people has Webber DGVs which are down drafts and the car runs very well.

The SUs are side draft and that's what came stock on the car so maybe Datsun knew this when the cars were build.

Is there really one that is type that is best for these engines? Is there one carb that is considered to be the best for the Z cars? Or does it really make any difference as long as what ever is on the car is properly sized and tuned?

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I guess it depends on what you want to do.

Power? Reliability? Efficientcy? Streetability? Low cost?

Best L6 with all those features would probably be a turbo engine from an 83ZX. So carbs are NOT the way to go if you want all of the above features.

Only reason I can see for carbs would be for simplicity. A simple carb would be to go with the Holley 390 4 barrel downdraft. Good American carb that's simple and has good support (and the Datsun runs great on it). Just a thought.

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Really? I remember reading that putting a 4 barl. on these does not make them run very well. Reason being is that cyl 1 & 6 tend to run too lean and cyl. 3 & 4 tend to run too rich; or something like that. It has to do with the design of the intake and where the carb sits. After seeing a pic of the intake I can understand this as the carb sits right on top of the pipes that go to cyl. 3 & 4 and there's a ways to travel to get to cyl. 1 & 6. Now keeping in mind I'm far from knowedgable, thus my question; this is only what I read.

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but thats me, and i have yet to see any car making real power use the 4 barrel conversion, i would either go with round top su's or if you have the engine, and the cams and set up for it go with the triples.

you will never get the power you can out of efi but thats another subject.

heres another thought, norm from north carolina, built and runs daily a 71 240Z with su's on his and i mean this very literally junkyard stroker motor and his best time at the track is 12.8 or 12.9 im not sure which but that is on ALL MOTOR and SU's.

so take it from there.

me personally i like the very simple and effective su's

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