[Spridgets] Why Does Engine Like to Run Rich?
peter at nosimport.com
Tue May 26 10:24:32 MDT 2009
If you pull the bell and piston/damper assembly off, you can
look down the jet and see the fuel level. You do not take off the
float chamber lid. I suspect your float level is too low. Maybe you
have that run of needle and seats that are too long? If you have a
mechanical pump, you can use the priming lever, if not, run the
starter. Electric pump, let it run.
Hope that's clear.
At 10:29 AM 5/26/2009, Doug Altman wrote:
>Needle shoulders are flush with bottom of pistons per instructions. Jet
>adjusting nut is all the way up, entirely compressing the spring when I start
>to turn them down. This has always been my starting point. I'll check the
>jet height when the nuts are all the way up. When I do have the carbs leaned
>out to where the Colortune says they should be, I get nice, gray colored, dry
>plugs. How do you see the fuel level in the float bowl to compare it to the
>position of the top of the jet? If you take the top off the carb, the float
>comes out too and the fuel level changes (?).
>From: Peter Caldwell <peter at nosimport.com>
>To: Doug Altman <doug_altman at yahoo.com>; spridgets at autox.team.net
>Tuesday, May 26, 2009 11:08:13 AM
>Subject: Re: [Spridgets] Why Does Engine
>Like to Run Rich?
>Real quick coupla things.
>Number of flats down is from the
>point where the jet is level with
>the bridge.... it's not 12 flats from all
>the way up. You should see
>fuel about a 1/4 below the top of the jet when the
>bowl is full to
>the float shut-off.
>The needle's shoulder must be flush with
>the bottom of the piston,
>not up inside, or protruding.
>Soot may not be from
>richness, aka unburned FUEL, but from deposits
>of the unburned (and
>unburnABLE) additive in today's unstorable fuel.
>Fuel for thought. Gotta run
>At 09:17 AM 5/26/2009, Doug Altman wrote:
> >Stock 948 with good
>rings, stock rebuilt H-1 1 1/8" SU's. I've adjusted the
> >carbs per the
>workshop manual, used Colortune, and even Frank's trick of a
> >standard 2 1/2
>turns down (15 flats) on the jet adjusting nuts several times
> >over the past
>couple of years and they all point to running a lot leaner than
> >where the
>engine runs best. The engine starts, runs, and accelerates best at
> >25 flats
>down (over 4 turns) on both carbs. Right now it seems to accelerate
>when the front carb is even at 30 flats (5 turns) down. I've tried rich
> >needles but it runs for crap with these. Spark plugs are always black and
> >sooty. Why does it like rich?
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