[NSRCA-discussion] Mintor 1.70 Question

[Dean Pappas]

Hello Tim,
Let me see if I can offer a couple of experiments.
1) Can you fatten the idle mixture? That will help.
2) Your pipe is long, and long pipes lean the midrange, while short pipes fatten the midrange.
3) If you disassembled and re-assembled the engine, even a tiny bit of overtightening of the four screws holding the cylinder to the case will cause piston skirt and bottom end heating which will do ugly things to the base compression after warmup. This will cause leaning in both suction-fed and pumped engines. I forget the torque spec, but it was in the Mintor 140 review article in MA several years ago.
 
Hope that helps,
                    Dean 
Dean Pappas 
Sr. Design Engineer 
Kodeos Communications 
111 Corporate Blvd. 
South Plainfield, N.J. 07080 
(908) 222-7817 phone 
(908) 222-2392 fax 
d.pappas at kodeos.com 

-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Pascoe,Tim [Burlington]
Sent: Thursday, August 03, 2006 10:02 AM
To: nsrca-discussion at lists.nsrca.org
Subject: [NSRCA-discussion] Mintor 1.70 Question



Hey List,

        I've been setting up a Mintor 1.70 in a new plane, and am running into some minor difficulties. I first started running the engine last fall, and has some mechanical trouble which lead to some major needle twisting. After getting the mechanical trouble out of the way, I've found myself trying to get the pump/needles back to where they should be, with varying levels of success.

        The original symptoms seemed to indicate a lean mid-range on the engine; dying on throttle up after a down line, the odd backfire when spooling up from idle in the flat. I've been constantly richening the pump in an attempt to solve these issues, and it seemed to work at first. Better mid-range, no dead sticks. However, I am still getting the odd backfire, and I'm really afraid that I'm going to start busting stuff. I am now well in on the pump screw, much further than another Mintor 1.70 flier running the same fuel, and a long way past flush with the screw housing. The mid-range needle is also on the rich side of the setting.

        Any suggestions would be appreciated. The lines have all been checked, and they are fine (pretty much new anyway). The tank clunk is free, and the vent line is clear. Is it possible the backfire issue is in fact a too rich mixture, and I'm chasing the problem the wrong way?

        It's getting frustrating, as the engine is great in many other ways - very easy to start, phenomenal power, good throttle response. I'm running a 17x13 prop (soon to switch to the new 18.1x10) on an Aeroslave carbon pipe set approx ¼ to ½ inch longer than the Aeroslave recommended length, with Cool Power 15% for fuel.

Tim Pascoe

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.nsrca.org/pipermail/nsrca-discussion/attachments/20060803/40149f19/attachment.html