I had asked several questions recently about switching from my stock ZS carb
to a Weber DGV. Well, I've finished with the project and thought I'd share
back with the group some of my experiences since some others were going to
be making the same change soon. Now that the project is complete all is
working well and I'm extremely pleased with the improved performance.
The Basics - I have a 1979 Spitfire and replaced the stock ZS with a Weber
DGV with an electric choke and a Cannon Manifold.
Oil out the Dipstick Tube - I initially hooked up the valve cover vent hose
to the base of the air filter as per the design and got the dreaded "oil out
the dipstick tube" as others have had who've replaced the ZS with a DGV. I
tapped a hose nipple fitting into the Cannon manifold in the center just
below the carburetor and attached the valve cover vent directly to this. I
also put in a PCV valve in this line as I'd seen someone suggest. The guys
from Autozone helped me pick out a valve from a similar sized small engine.
That seemed to do the trick and stopped the oil coming out the dipstick
tube. I noticed that Vic Whitmore just posted a note saying he did the same
thing and it was successful for him too.
Hood Hitting the Air Filter - On the first test drive the hood rattled
against the air filter which I also understand is a common problem for some
with the Weber DGV with the Cannon manifold (but not with the Pierce
manifold). I solved this by placing some pieces of wood between the hood
stiffening bar and the hood. There are some foam pieces glued to the hood
at this point between the hood and the stiffening bar and maybe these get
compressed which might explain why some people have trouble with clearance
with the Cannon and others don't. I wedged some flat pieces of wood about
1/4" to 1/2" inch thick between the pads and the stiffening bar and this
helped to raise the hood up just enough keep it from bouncing on the air
filter. I'm also thinking one of the those Longflo airfilters would be good
too as it is rounded on the sides and thus not as high as the box shaped
Weber stock airfilter on the front and would be less likely to hit the hood
on the front of the airfilter where the hood is starting to curve down.
EGR Valve - I removed this. The cannon manifold did not have any pre
drilled points to attach this into. From the looks of the rubber diaphragm
on the valve (cracked and stiff) I doubt it was doing much good. I plugged
the EGR valve hole in the outlet header with a metric sized oil pan drain
plug.
Gulp Valve - As I remember this allows air from the air pump into the inlet
header during deceleration. I removed this since there wasn't a spot on the
cannon manifold for it. I suppose I could have tapped a hole into the
manifold, but thought I'd try it first without it.
Bob Bollinger
79 Spitfire
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