Dellorto DHLA40 Needle Valve Issue

[Hardway]

I have a set of triple DHLA40 carbs on my 240z.  I have the fuel pressure set at only 2.5psi and the front carb started dripping fuel out of the bore.  Thinking the needle valve was not closing all the way I took the top off and using my vac. gauge at the fuel entry port, it will hold vacuum with the float all the way up.  However, just the slightest drop in the in the float releases the vacuum.  I sprayed some carb cleaner down the fuel entry port and around the needle valve itself.  It did not help any so I bent the floats a little so it force the floats to sit higher and ensured they were not rubbing against the body of carb.  This helped but I noticed when try to adjust the idle a little bit of fuel started to creep out of the bore of the carb.  I went ahead and did some idle tuning but when I would rev the engine the front carb would pop/spit when revving up.  I believe this is because the floats are now too high and starving the carb of fuel.  Does this prove the needle valve is not working properly?  Is there anything else I should be looking at?

[Mark Maras]

I agree with your diagnosis. The needle valve appears to be the problem.

[Hardway]

Thank you Mark.  Been researching if I should go with Viton tipped needle valves or just stick with brass.  I see pros and potential cons for each.  I have read a few instances where users have indicated the Viton tips have come off and plugged the fuel port. However, there are lots of users who have had great success with them.  The research continues!

[Mark Maras]

 I've used both types over the years. Never had a problem with either as long as the fuel is clean.