Just a guess:
When the engine revs won't come down quickly in most cases it is overriched
mixture.
Does your butterflies move freely?
Does the linkage block on full throttle?
I ran the Weber DCOE's only one time without soft mounting and they didn't
perform well.
I use overdrive springs for the anti-vibration mounting. They are stiff enough
and last.
Sorry that I can't help more.
Chris
----- Original Message -----
From: "Joe Guinan" <joeg@neb.rr.com>
To: <fot@autox.team.net>
Sent: Thursday, December 07, 2006 5:08 AM
Subject: [FOT] Dellorto/Weber Fuel Foaming?
> I'm running dual Dellorto DHLA40 carbs on my street/autocross Spitfire, and
> am having some troubles. These are quite similar to the Weber DCOE, using
> the same manifolds and filters but different jets (which of course have to
> be ordered from Europe) - so I'm hoping someone running DCOEs has run into
> something like this problem. I swapped from one set to another and found I
> had a several of the Thackery spring washers broken. I simply replaced
them
> with nuts an bolts with lock washers. Now I'm having a hard time getting
> the engine revs to drop back down. When I shift, the revs actually climb.
> I am using the plastic anti-vibration mounts with the large O Rings front
> and back. I put on some new return springs, and the butterflies snap
closed
> on both carbs. I don't seem to have any air leaks around the manifold to
> carb junction. When running the engine without the vent covers on the
> carbs, I observe some "splashing" of fuel above the jets. That might be
the
> source of extra fuel, but I still think I must have to find a source of air
> getting through as well.
>
> My question is, "What are the typical symptoms associated with fuel foaming
> from vibration of the carbs?" I may not actually be getting foaming, but
> simply getting some sloshing around that ends up with extra fuel draining
> into the throats of the carbs somehow. I do have another set of thackery
> washers, so will probably put those on first and see if the problem goes
> away. If it still acts the same way, I'm going to have to pull this set of
> carbs off the car and see if I can figure out what is going on. Maybe
> someone could point me in the right direction?
>
> I searched the FoT archives because I remembered a short discussion of
> thackery spring washers vs. rubber cushion washers. Mark B mentioned
using
> the rubber washers on the top bolts where they won't get destroyed by
> gasoline, and the thackery washers on the bottom mounts. Sounds sensible,
> and I'll be doing that when I find a source of rubber washers. Will try
> Fastenal tomorrow.
>
> Joe Guinan
> Fremont, NE
> Spitfires
>
>
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