Round Tops Fuel Systems
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A BETTER CARBURETOR for the datsun z...

Round Tops SU Carburetor Z

It all started when…

I couldn't get my Datsun 240Z started on a cold morning.  I tried fiddling with the choke, spraying carburetor cleaner in to the intake, and cranking till I wore out the battery.  "There has to be a better option!" I thought to myself.  After about 2 hours of trying, I gave up.

Round Top Fuel Systems was born from frustration with the old hitachi carburetor set up, tons of hours of trial and error, and a strong desire to make a better carburetor for the community of classic Z lovers.  This one's for you!


Why Round tops?

100% Brand spanking new genuine SU carburetor.

The first dedicated carburetor set for Classic Z cars, for us by us. 

Handmade to order, quality craftsmanship and dedicated support.

Track tested, mother approved!

Round Tops SU Carburetor Z Laid Out


Improved materials are now able to accommodate ethanol mixed gasoline.

Adjustable metering allows a selection of fuel types, either for highway use or racetrack.

Round Tops SU Carburetor Z Comes With


Internal float system is more stable with cornering forces.

Bi-metallic thermally compensating mixture adjustment adjusts for temperature changes.

Improved manufacturing technology and materials for more reliability.

Flow through fuel bowl eliminates vapor lock.

Round Tops SU Carburetor Z Upside Down


The cold start on the HIF has the advantage of being an enclosed enrichment valve and not repositioning the jet as on the HS carb. This leads to fueling being more reliable over the life of the carb between servicing.

Performs better in dyno testing than original equipment.



Round Tops SU Carburetor Z Sideways


A huge selection of needle/seats to for any climate, and any standard configuration.  The flexibility to accommodate changes in camshaft /valve /manifold /ignition with 'off the shelf' components. 

Access to linkage, filters, and accessories available from SU and other after market suppliers.

Round Tops SU Carburetor Z Bottom


 100% New genuine SU carburetor manufactured in the U.K. handmade to order.

Improved technology and the benefit of over 50 years of manufacturing performance practices to create a superior carburetor.

Includes a manufacturer warranty and factory support.