Well,
here's the definitive answer: Yes. Absolutely! Use oil in your
carbs! Beyond that, everyone has a different opinion. Actually, I've
got 20wt in mine right now... Having said that-
The damper oil, variable venturi and dashpot act as a reverse
accelerator pump. Vacuum opens the venturi, and the needle below
adjusts the fuel flow accordingly. The problem is, when you pop the
throttle open, vacuum spikes instantly, opening the venturi, but the
engine takes time to spin up and draw large volumes of air. The oil
controls the opening speed of the venturi, preventing the dashpot from
rising too fast and dumping a bunch of gas into the (still
slowly-moving) intake air. It also acts as a shock, keeping it from
oscillating and bouncing around...
So if the oil's too thick, it'll just take forever for the dashpot to
open, and your engine to develop full power. If it's too thin, however,
you'll bog down when you floor the throttle from low speeds. So there's
no real harm in experimenting, really. I run 20wt in the 1600, and on a
cold day, it's way too thick. But on a hot day, after a long run, it's
pretty good. The 122 (with 1 3/4" carbs) does fine with ATF as long as
I don't floor it from idle.
I'm sure others have more to add...
Toby B
currently a captive of Paul Allen's musical ego...
> Date: Sun, 19 Mar 2000 08:40:08 -0800
> From: "Jon Wissler" <Jon_Wissler@pngc.com>
> Subject: SU Carb Oil Question
>
> Here is another classic neophyte (aka stupid) question concerning
> which oil to use in SU carbs. I have told to use 10W, 30W, and ATF from
> various sources. What does this learned list have to say on the subject,
> and are there different conditions to warrant the use of different fluids.
> Thanks in advance for the advice.
>
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