Date: Wed, 16 Aug 2006 17:31:37 -0700
Reply-To: Mike Rouby <mikerouby@YAHOO.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Mike Rouby <mikerouby@YAHOO.COM>
Subject: Re: Carb conversions?
In-Reply-To: <000001c6c192$5b270e30$6400a8c0@MASTERPC>
Content-Type: text/plain; charset=iso-8859-1
Dennis,
Many valid points. Some of those you make sound a lot worse than it really is, but granted the 'potential' is there for such issues.
As for the "preheat" issue with center mounted carbs, Weber makes a remote snorkel to suck heated air and resolve this issue. If you live in a cold or rainy climate, I would highly recommend one. Plus in the Vanagon application it may allow for better fitment anyway.
http://www.jameng.com/products/images/99217.090.jpg
I take it you're an EFI fan. Thanks for the counterpoints. Most appreciated.
Dennis Haynes <dhaynes@OPTONLINE.NET> wrote:
I have had experience with many carb set ups for many cars over the years.
While carburetors appear to be an easy solution to FI issues there are many
drawbacks. Worse, most conversions do not address issues that OEM carb set
ups used as early as the 60's. Most kits are strictly, make it run, limited
use fair weather installations. Here is a list of features most kits for
VW's are lacking.
Throttle Dashpot or positioner! When the throttle is closed for idle, direct
vacuum is used to draw a fuel mix through the idle circuit. If over running
the engine such as going down hill, this device delays throttle closing or
may even hold it open so that fuel is not directly sucked into the engine
without some air for it to burn. Can we say backfire, raw fuel in cylinders,
black smoke?
Choke pull off/Heater! Moist after market either do not have chokes, or the
choke is operated by heater element, not engine temperature. Further, start
engine for short time, shut off while choke is still closed and throttle
held open and gravity will empty the fuel bowl directly into the cylinder
with an open valve. On the type 2, this is real fun as the entire fuel tank
can drain into the engine. BTDT! Can we say Hydro-Lock?
Idle Shut Off Solenoid! I like the lack of this one. Yea, go turn off the
engine. After a long hard run, Hope you a manual trans so you can pop the
clutch in gear and get it to stop Dieseling!
Manifold heat! This is a real problem in winter with center mounted carb
kits. The fuel will sort of puddle in the manifold. Can we say flat spot?
Oh, no intake air preheat either. You drive along for 10-15 miles and the
engine just stops. You coast to the side and a few minutes later it runs
again like nothing ever happened, for another 10 miles. Vaporizing fuel +
what? Refrigeration. Add moisture in air and can we say carburetor icing?
EGR ports! Air cooled Vanagons will miss this one. Excess NOx, burned
pistons.
How about proper porting for 2 stage distributor advance?
Crankcase Breather the works?
Fuel Vapor control!
Air filter with adequate flow and the ability to trap dirt!
Oh, I can go on.
Dennis
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