SU carb/ running issues

[Mark Maras]

 In the first post, you mention "completed the basic fuel mixture setting on the SU's 2 1/2 turns down". The 2 1/2 turns down is a secondary, fine tune, adjustment. The float height adjustment is the primary mixture adjustment. 

[Blitzed]

Hi All,

You all are brilliant. The 240 roared back to life after a very long sleep.

Adjusted all the linkage to neutral, high revs gone. I'm out about 3 3/4 - 4 turns on the air mixture nut. Backfiring and stalling gone, engine will hold a 700 - 800 idle.

New issue, can't rev the engine, front carb backfires with the introduction of air and fuel. Rear carb reacts fine. Engine is now dieseling at shut off. These SU devil's are tricky to tune.

Thanks for all the advice, Cheers. 

[240Znomad]

Blitzed,

I recently went through many of the same issues getting my '71 240Z back up and running after sitting idle in the garage for 28 years.  As Mark just mentioned, the mixture adjustment nuts are just for fine tuning the mixture, you've got to get the float bowl level set correctly first for the adjustment nuts to work properly.  If you're down 4 turns and still backfiring out the front carb, it sounds like the front carb needs the float level checked and adjusted to "richen" it up.

I noticed your location says Placentia, is that Placentia, California?  If so, I am just a few miles away in Orange.  Let me know, I would be happy to stop by and give you a hand.  I am by no means an expert, but two eyes may be better than one to help get it sorted out.

[Blitzed]

Hi Nomad,

That would be awesome. Love to see your car and your vision moving forward. Give me a call this weekend if you have the time. 

send me your contact info we'll and set a time. anwhiteford@att.net

Thanks,

[Blitzed]

Hi All,

Big "Thank You" to Nomad, took the time to help another Datsun nut. 10 mins in my garage looking at the engine and discovered my throttle linkage was still slightly engaged, fixed. Pulled the distributor and adjusted the plate bolt so we had additional advancement on the timing and showed up with a set of SU, so he could explain the internal issues and working of the carbs. Engine is purring and we took the car out for it's maiden voyage (around the corner). 

Still need minor adjustments to the float levels as engine is running slightly lean but it's running. 

Where can I locate a new/used (working) vacuum advance for the distributor? VA is currently moving but too weak to advance the plate. 

Thanks to all who have given great direction on SU's. 

[Patcon]

@240Znomad

Kudos to you!!!