Kevin,
Waaaayyyyy back when, I started out with a
Weber TB – no jets, but it had four fuel injector positions. It was dual
throat with each throat being 50MM in diameter.
After 2 years of flying with it, I took
the Weber TB off and build my own “Dynamic Chamber” intake.
Performance improved dramatically. I went from a top speed of 186 MPH in my
RV-6A to 196 MPH and my ROC increased by over 300 -400 fpm.
The lesson I learned was that what was
supposed to be the “cats Meow” for an RX-7 Turning 9000+ rpm did
not work well for aircraft application. If you are using TB with electronic
Fuel injection – then the diameter is probably not as critical a factor,
but tuning a carb the airflow velocity is much more critical and therefore so
is the diameter, ventures, air values, etc. That is one reason I went with
electronic fuel injection – I think it is a whole lot easier to tune than
jets. But, if you have an expert (someone who has done it successfully –
like Ken Welters) then you may get it sorted out.
But, it does sound like your engine is swallowing
too much fuel – I presume you have an air/fuel ratio indictor of some
sort? What was it showing – rich? Lean?
Ed
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Tracy Crook
Sent: Friday, April 02, 2010 7:27
AM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: my weber
- dcoe52mm
Welcome to the world of
carb tuning. Hopefully Ken or Lynn can point the way. It took me 2
months of fiddling with the Mikunis to get them right but that info won't help
on the Webbers.
Why 52mm? Have you been talking to Paul L? Mighty big for an airplane
motor. YMMV
Tracy
On Fri, Apr 2, 2010 at 12:43 AM, kevin lane <n3773@comcast.net> wrote:
my engine runs, roughly, hard to start, but
I can make it run. stock jets are F7/180 and F8/65. I'd guess
these are running quite rich. [went thru the ˝ gallon of fuel really
quickly, even tho' engine ran but a few minutes, max] thought I'd ask the
group before I start changing things. ken welter said he'd help since
he's been thru all of this before.
I also need to mix up a new batch of
fuel. guessed at the first, because I didn't have a way to measure ˝ oz.
of oil to add to a ˝ gallon of gas , and probably put WAY too much in.
still haven't gotten a timing light to check how my DIS is actually firing.