Tuesday, December 18, 2012

Goodbye EFI, hello carbs!

Now that we have the exterior of our Z project looking the part, the time has come to address a few other problems that need fixing before we can get the car certified and road legal. Although the L28 was running prior to its stay at GT Refinishers earlier this month, unfortunately it failed to start once it was parked back up in the garage! The ancient Bosch Jetronic fuel injection system had given us problems before, and it looked like it was doing it again - the more we looked into diagnosing the problem, the more tired and broken parts we kept finding. Would it even be worth fixing? After all a cert plate shows either fuel injection or carb, and we were also always planning on switching to triple carbs and a high-compression motor rebuild next year. If we got the car certified now we would have to get it re-certified again (in theory, anyway) when we did this. It suddenly made a lot more sense to switch to carbs now rather than later, to get the engine running again (reliably!) and save us money down the track.

After a bit of research, it seemed like early round top twin SU carbs would be the way to go for now, and thankfully our friend Mikey had just pulled out a set when he took the L24 out of his 240z, and agreed to sell them to us. It was a pretty simple switch over - gaskets, fuel pump, fuel filter and a few other bits and pieces. Though the aftermarket headers we already had were hitting the bottom of the carbs to start with, amongst a few other issues.

It's amazing that the manifolds and carbs bolt straight up and after a bit of messing round with a few bizarre problems (a sensor in the airflow meter tells the fuel pump to run, for example!) it fired straight up.

A quick drive around the block showed that it both idles and drives perfectly fine, which seems crazy! We will get the carbs tuned properly of course once the car is back on the road to make sure it's not running too lean, but for now, we're just happy it's moveable!


  1. Ahh so you when the carb way. Kudos to you girl I don't even wanna mess with carbs sense my motor choice for my 260z but than again I don't have the stock motor otherwise I'd Probly keep. Keep up the killer work your decisions in ur builds never fail to amaze me

  2. Twin SUs are the way to go for daily drivers. Triple Weber carbs look amazing and sound amazing but should be thought about later. They are meant for racing applications/top end and don't like being driven slow. Get a filter on there! Excited to see what you do next with your Z. I am going the opposite way with my Z, first engine which Ive just about finished and now I am concentrating on the body/interior with some nice additions.


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