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Engine basics => Engine set up tips => Topic started by: Allen Eshleman on May 04, 2011, 04:47:06 AM

Title: B-40 NVA problem
Post by: Allen Eshleman on May 04, 2011, 04:47:06 AM

Tuesday evening I took my reworked Nobler - reworked after a horrific crash - beautiful rebuild by my brother - to the field for the first time.  Balance and flying qualities were better than ever.  It has a Brodak 40 in it which has been a wonderful engine for me.

However, on the third start up - the Needle Valve would no longer adjust the engine speed.  Later, it started to move around without being touched.  It seems to be tight now that it's on the table.  Any ideas?

Title: Re: B-40 NVA problem
Post by: Balsa Butcher on May 04, 2011, 08:05:38 AM

Idea...yes. Some B-40 spray bars have "burr" in the threads that causes the NV to jam before closing all the way. It is common. Remove the NV assembly and carefully thread the NV back in. It may take a few times but once you hit the correct threads and it should go in further and work correctly. You can test by hooking up a piece of fuel tubing to the spray bar. When you blow through it the NV should cut off the air flow. You could also replace the NV assembly with a PA NV assembly...problem solved forever. 8)