this is going to sound stupid but which direction closes the choke on the round top carbs?

On the choke handle inside? Forward.

ahhh ok thought so. been trying to get it to run with out backfireing threw that carb and didnt know if the choke was off or on...

Thats almost like one of those questions from the IQ test you sent me Keith. The chokes are Closed when the handle is toward the rear. They are off/open/not in use when the handle is forward.

"Open", "closed" Isn't good terminology for SU's The chokes don't work that way. "Up" or "Down" could work better, but not clearly. Pulling the handle lowers the nozzle, a juicy pool of gas forms at the top of the lowered nozzle ready to be sucked up by a cold L motor.

Even with Mikunis, "open" would describe when the choke is engaged, as the choke "starting circuit" is open when you pull the handle and "closed" for normal operation.

But, "Close the chokes" is still accepted as engage the chokes. After all, the iconic symbol for choke is a butterfly valve closing a venturi. Looking down the throat of all my old American steel, it was easy to see if the chokes were closed.

Pulling the handle lowers the nozzle, a juicy pool of gas forms at the top of the lowered nozzle ready to be sucked up by a cold L motor.

Sounds almost sexual. Good description. Victor.

Victor, you're right. I've learned alot about these SUs lately, and by pulling the cable you are pulling the nozzle jet down and this changes the fuel level at the bridge. And yep, the gas is richened for a cold start,and is slightly pooled at the bottom of the carb. You can't see this unless you have your air filter off, and carb apart. If you have someone pull the cable you can watch the linkage pull the nozzle jet down under the carb. No butterflys doing work here. Your throttle cable / pedal works the butterfly in the carb.

My Z has the choke cable removed (nozzle springs still there)smog, vaccum lines and anything else that is not required on the track. Not street driven, to bad, but sure looks better with all the garbage off.

Sounds almost sexual. Good description.

Is there anything not sexy about a sweet running Z car?