----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]----
Ed Robbins wrote:
> You've always been
a proponent of a mixture control. I'm
> now convinced and
would like to plan some trips over the
> mountains to
>
> What unit would you
recommend I look at for my mechanic to install?
Ed,
The .pdf article supplied by James Beach
Brennan is golden. I’ve saved a copy for future reference. Reading
through all the mixture control info, it all looked good and right to me. And,
I doubled or tripled my knowledge of the Stromberg carbs.
I’d make four additions to what the
article says:
- The
article mentions that the air passages through the carb, used by the
mixture air, can get clogged with carbon. I had those passages get
clogged in flight by fibers from a washed air filter. Blocking the air
passage caused excessive leanness and very rough operation. Pulling carb
heat to richen up the mixture helped and I only had about 6-10 miles to go
to the destination airport when this manifested. It’s worth never
cleaning and reusing the air filter IMHO.
- When
hooking up the mixture control for first use, my very good mechanic pulled
the carb out the plane when I landed after the incident above in #1. He
cleaned out the air passages. I asked for the mixture to be hooked up.
He found the mixture mechanism filthy from 10-30 years of no maintenance.
He cleaned all parts, stropped the two plates together (the moving and
non-moving ones) put it all together and hooked up a cable. It worked
fine ever after though I would recommend that you get that mechanism
cleaned periodically.
- I
found that the Stromberg carb works accurately. However, since it works
through the change in air pressure in the float chamber, it seemed to take
a few seconds for changes to be seen. Be patient. Make a change and
watch to see the results.
- I
liked using an accurate EGT for leaning. It makes me happy. I guess, if
the manufacturer of the engine says you can do it by RPM, you can do it
that way. For me, I got very little rpm increase or decrease as I changed
the mixture in cruise. However, I could clearly see the change in EGT
using my highly accurate K&S gauge. And, I could clearly see the
difference in fuel consumption and high-altitude climb.
I recommend the use of a
digital EGT gauge in these modern times. Then, you can clearly see the peak
and control how many degrees rich you make the setting. By some reference book(s),
I learned that best power is 100° rich of peak, usual cruise is 50° rich of
peak. There may be newer or better information on the preferred EGT
temperature settings. You shouldn’t have any problem getting a form 337
approved for even a non-TSOed EGT gauge – I think.
Definitely read that entire .pdf that Beach
provided. (I’ve asked permission to put it on my website or to get a
link to its permanent web location.)
All the best,
http://edburkhead.com
ed -at-
edburkhead???.com (change -at- to @ and remove "???")
============================================================================== To leave this forum go to: http://ercoupers.com/lists.htm Search the archives on http://escribe.com/aviation/coupers-tech/
