Hitachi Dual SU's (bell top)

[YO510]

I was wondering how much of a power difference I can get from replacing my carbs to dual SU's. I'm currently running all stock, but have a set of dual SU's lying around; will I even get a noticeable amount of power increase, or should I just go ahead and sell it?

For the future, I plan on swapping an l20b or an NA sr20.

[okayfine]

I'm currently running all stock, but have a set of dual SU's lying around; will I even get a noticeable amount of power increase, or should I just go ahead and sell it?

It will be noticeable. Some additional tuning will be necessary to get the most from them, but stock for stock you could see 10% more power or so. www.datsuns.com has a couple dyno charts you could use for comparison, if you were so inclined.

For the future, I plan on swapping an l20b or an NA sr20.

I've run SUs on both!

A bit more work still, but doable, in case you were wondering...

[YO510]

Didn't want to start up a new thread, so:
I've been waiting to buy an l20 first before I swap carb's, but I'm going to go ahead and put them on my l16 and most likely put them on an l20 when I get one.
A very very elementary explanation would be great because I'm not too great with cars (in general).

The carbs are rebuilt and complete. What is the best way to split the fuel line going from single to dual carbs? How hard is it linking the throttle from stock to these su's? How much tuning would I have to do after? and how hard is it? Would I have to make any changes to timing?

[okayfine]

What is the best way to split the fuel line going from single to dual carbs?

Best way is to use the factory SU fuel pipe, which does the splitting. Beyond that, anything that will connect to your fuel hose and is fuel safe (such as brass tees) will do the job.

How hard is it linking the throttle from stock to these su's?

If your car's linkage is complete and your SU linkage is complete, the easiest way is:

DQ Volume 11 Issue 2 - Tech How-To: SU Linkage Bracket — Plans for building a small bracket to correct the alignment of the throttle linkage when using SUs on an L20B.

How much tuning would I have to do after?

Minor to major, depending on the state of the carbs, your experience, your engine build (L16 sure, but bone stock?) and the parts on the carbs such as the needles. It could take an experienced hand as little as 15 minutes to dial in your carbs. Too many unknowns to give you a concrete answer.

Would I have to make any changes to timing?

Depends on what your timing is now. Generally it isn't required, but timing is more to do with your gas quality, cam, and ignition curve than carb type, IMO.