[NSRCA-discussion] Mintor 1.70 Question

[patterndude at comcast.net]

Tim,
Gray is right in that the pump is capable of spewing fuel if set at 1/4 throttle and hit with a starter - if the pump pressure is too high.  Your symptoms sound like a lean engine.  Backfiring is a lean symptom on this engine.
  You made a statement about the pump mod that worries me.  I never recommended removing the plastic insulator.  Quite the contrary.  The mod detailed on our website shows how to use one long screw to pass thru the pump, insulator to the backplate instead of the old factory setup.  The new engines are already done properly (as by my suggestions).  The insulator is very effective at preventing boiling fuel due to overheating (leading to lean engine symptoms).
  Please review the tuning tips on the website if you havent already.  Another tip: too much pump pressure will dump fuel into the engine as a liquid and cause the engine to overheat (need the vaporization from the carb).  Amazingly this engine will run when others won't so you can get an engine that runs hot due to this.  Which could lead to heated fuel if you've removed the insulator which leads to unstable fuel delivery.
  The needle should be about 1 to 1.25 turns out.  The pump screw should be just inside of flush.  You can damage the pump if you screw the pressure adjustment all the way in to its stops.  The pump adj threads are all the way through the backplate, but the adjustment is pressing a spring into a flexible diaphram. If you over screw the pump it will permanently distort the diaphram.  I state several times that pump adjustments should be +- 1.5 turns or you have some other problem.

Feel free to contact me directly if you like or we can stay on this list.
--Lance

--
District 6 AVP 
www.aeroslave.com

-------------- Original message -------------- 
From: Gray E Fowler <gfowler at raytheon.com> 

Tim 

I am going to guess that it is a pump problem. My reasoning is that if you have increased the pressure, and the pump is working, when you are at idle with high pressure, and spin the engine with a starter, no glow attached, it will flow massive amounts of fuel out of the carb. Also with higher pressure and a properly functioning pump, you would be required to lean the idle mixture alot. 
Other than the over heating of the pump without an insulator, these engines have not experienced many pump problems. 
Contact Lance, he can help you trouble shoot.  Lots of people treat engine "A" like they did engine "B" because they think all engines and brands are the same, which is not true, and then they chalk up failure to "Bad Engine", because we all know that their experience and knowledge are without question. How do I know this? Just ask them, they will tell you. 

Contact Lance at  patterndude at comcast.net  he will get you fixed up. 

Signed, 

The "mean half" of AeroSlave


Gray Fowler
Senior Principal Chemical Engineer
Radome and Composites Engineering
Raytheon 
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From: Gray E Fowler <gfowler at raytheon.com>
Subject: Re: [NSRCA-discussion] Mintor 1.70 Question
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