2025-09-04 Carb Cleanup

Had a couple of hours after getting home from the office, so went to the shop to see if there was a task that could be done in that time.  Checked the suspension parts in the paint box and needed to do a bit of touch-up.   Okay, that means the strut was not going back together.  

Time to investigate the carbs and the rich mixture issue.  I figure, like all Zenith-Stromberg carbs, the piston diaphragm will be worn out or torn.   Off comes the airbox.   Disconnect the vacuum hoses.  At least the ones that were attached.  Will get back to this later.  

There is an oil leak somewhere.  This is much more than the average LBC, so I needed to trace it back.  Ugh, it is grimy.  

 Is there something supposed to be in this hole?

Z-S Carbs 

Pull off the dome and piston of the front carb.  Normal rich mixture appearance.  Break it down 

At the very least, the needle is in perfect shape.

Not overly bad base.  

From the front

With both domes off, a little carb and parts cleaner, then wipe down the front carb.   Big difference.  But this is on the initial clean

After a quick sonic clean of the domes and pistons 

Now the piston edge can get a proper cleanup with a 3m pad.  I really need to clean the edge for the diaphragm.   

After this round of cleaning.  Test the movement of the piston in the dome.  In this case, there was a little resistance.  

In my opinion, you should be able to spin the dome on the piston to ensure it is a smooth operation.  Well, I used a little liquid polishing compound on the piston shaft and run it up and down and around.  

After, clean the shaft with parts cleaner.  This is the amount of crap that came out.

Time for the spin test. 

The last thing is to adjust the needle level, and this is the only tool.  BUT it turns out the internal screw is stuck.   Some penetrating oil and leave it overnight.  Hopefully,  it will soak into the rubber part and free up 

 The tool 

Oil "Leak"

While the airbox and carbs are apart in the sonic cleaner time to look at the oil build up.  All I can do is spray down with cleaner and see if I can find the leak.  It is not subtle 

I need to find a vacuum map cause there are some lines disconnected that I do.  Messy.

That is enough for tonight.