Mark Maras

What do the other plugs look like and how did the car run?

DITTO

Oliver's email address is zman@zspecialties.com

@240260280 Glad you brought that up. I couldn't remember how far to lift the pistons. I looked for the proper distance but couldn't find it except a British SU site. What is the proper distance?

@jalexquijano Prior to checking the mixture two things must be done first. The valve adjustment and ignition timing MUST BE CORRECT. Checking mixture. Use the piston lifting pin located under the side of the carbs. to check the fuel air mixture. With the engine running at working temperature, use the piston lifting pin to raise the piston about 1 mm (1/32"). If, while the piston is raised 1 mm, the engine speed increases briefly, then returns to normal, the mixture is correct. If the engine speed raises and stays high, the mixture is too rich. If, when the piston is lifted the engine speed drops or the engine dies, the mixture is too lean. Let us know what you discover.

@Redwing I'll check with Oliver to see if he has the right side and the long rubber center piece.

It would be better to see where the fuel level is before readjusting. Pull the domes and pistons (not the float covers). When you pull the choke on, the nozzles will lower and you'll be able to see the fuel level above the nozzles. Look and see if the rear carb fuel level is close to the front carb level.

Did it stay at the scene of the accident and call 911?

Yes. Then start it up, shut it down and check the fuel levels again in both carbs at 2 1/2 turns to be sure the fuel level isn't too high and pooling on top of the nozzles.

Canards?

@jalexquijano I agree with Cliff. Raise the fuel level in the rear carb to the same level as the front carb. Reset the mixture screws to 2 1/2 turns, check to be sure that fuel isn't pooling on top of the nozzles and drive it. When the engine is warm, if the engine seems like it lacks power under acceleration, SLOWLY pull the choke while accelerating. If the fuel mixture was too lean, adding choke will richen up the mixture and you'll feel the performance boost under acceleration. If adding a little choke improves performance, drop the mixture screws 1/2 turn and try it again. @siteunseen Tick tock, tick tock! Time keeps on slip'n, slip'n, slip'n, into the future. Fly like an eagle.

I'd reuse it.

@jalexquijano Where are your mixture screws now and how is it running?

I've been considering this possibility and It could be that minor variations in the fuel height don't make much difference. It could be that this float level discussion is "much ado about nothing." Then I thought about a lower fuel level and how it would affect the choke. Pulling the choke on will have less effect if the fuel level is low. Dropping the nozzles and allowing fuel to puddle on top of the nozzles is the choke action. It would probably only affect cold starting if the fuel level was low and the temps were frigid. Like trying to start your Z in the garage in the dead of winter.

I think we're all hoping for some clarity on this. Thanks in advance.

Will the rpms drop if you pull up on the pedal? I'd start raising the mixture screws in 1/2 turn increments to see if the dark plugs will clear up.

I agree. that's why the 1/16" (1.58 mm, 1 1/2 turns) below the nozzle top. It allows adjustment without fuel puddling on top of the nozzle.

Actually Jalex reported some progress. In post #283, in his last performance description. He said that the car was running better than before, albeit at 3 1/2 turns. That tells me the float (fuel) level needs to go up another mm and recheck the nozzles at 2 1/2 turns.

All I can gather from this is the fuel level isn't critical, which I know is BS. In group A, we have the 23 mm fuel level with the nozzles at 2 1/2 mm, leaving the fuel level FAR below the nozzle top. In group B, we have the 1/16" below the nozzle top at 2 1/2 turns. Both groups say they have had success using these settings. I have no explanation for group A's float setting. @jalexquijano, Keep raising your floats to 1/16" below the top of the nozzle at 2 1/2 turns down.

I agree, unfortunately I don't have the computer skills to do that.

@240260280 I read Brian's write-up on setting floats 10 turns down, 23 mm fuel level. All seems good until you read his opening paragraph under "Setting SU Float Bowl Levels". He says 2 1/2 turns down is the proper setting. Note in his instructions that he doesn't return his mixture screws to 2 1/2 turns. It can't be both ways.

I put a dab of red RTV on those spots that are prone to leakage.

Found it. '72 SU Float Level 2/20/12. "When all is said and done and the nozzles are where ya like' em, the fuel level as viewed down in the nozzle should be about a 1/16 of an inch below the top of the nozzle. Puddling up on top of the nozzle, things'll get fat and contrary to that if the fuel level is too far down the nozzle things'll be lean." That statement comes from Bruce Palmer. If "where ya like'em" is 2 1/2 turns the fuel level should be 1/16" or so below the top of the nozzle. There's no way, IMO, that the fuel level is supposed to be 10 turns down UNLESS the 10 turns down (23 mm) fuel level is with the float removed. The fuel level raises 7 1/2 turns when the float is installed putting it at 2 1/2 turns down. Anyone?

@rossiz You rebuilt your carbs a few years ago and your Z runs great. Where is your fuel level?

That's not another worm in the can. I use that method to set needles too. Another worm in the can is when we start pulling the SM needles out of the pistons a bit to clean up the idle. But that worm is down the road.