DamBest Carb Modification
This page is for some of the modifications I did to
my DamBest Carb. It is a "Dirt 358 Open Carb"
Model good for 500-750Hp. I had a few issues with
the camshaft that was in The Ripper, and had to
modify the carburetor to make the idle adjustments
work better as well as some improvements in fuel
control when closed throttle. All were simple.

The modifications include adding an air bleeds jets
to richen up the idle circuit, adding secondary jet for
better fuel control and finally throttle blade holes to
help bring the throttles back closed so they are in
the idle circuit and not drawing off the main.

I just followed John's directions and all in all carb
worked great, idle was easy to adjust and all
seemed well.
The DamBest Dirt 358 Open Carb in all its glory
First change was to put in a jet for the 3rd Level Idle circuit.
The Jets are actually 3/16" 8-32 brass allen set screws. A
quick check for a part number from McMaster Carr and I
had them the next day. The jetting that was suggested
was a 0.052" hole in all four corners of the 3rd Level Idle.

I didn't get a picture of the Idle Air Bleeds but they also got
the same treatment, a 0.052" Air bleed. Nothing was in the
carb as shipped, so this served to fatten up the Idle circuit
a bit.

I made a little jig threaded for 8-32 screws out of a block of
aluminum and put the set screws in, and just drilled them
out. Pretty simple, no broken bits either!
After that task I moved onto the throttle blades. This
modification would allow more air to pass without having
to open the throttle past the point of the idle circuit control.
With the low vacuum at idle the throttle blades were too far
open for good idle mixture control so this fix allowed me to
close the throttle blades back to a good position to allow
the idle circuits to work properly (and be adjustable). John
suggested a 0.125" hole located close to the idle fuel hole
(or what ever it's called). You can see each blade has its
hole offset to the idle fuel passage.

I used Blue tape to seal up any exposed holes and slots
so none of the drilling bits could get in. Then a shop vac
did the rest.
A bit closer shot to see what I'm talking about. I'm
guessing that this will promote better mixing of the fuel
with the incoming air stream from the hole in the blade.
The Bottom view, all back together. The DamBest carb
comes with nice reusable gaskets. It came apart clean
and easy. Another nice thing is the fuel bowls have a  
sight glass to help with float adjustment (not shown). I
think most parts of the carb are made by DamBest except
for the fuel bowls. The carb is also much lighter then the
Holley 830 Nascar version it replaced, and looks a ton
better. Hopefully it makes more power too, but that being
said, it definitely more responsive then the larger 830.

One interesting thing about blowing the engine, the spark
plugs show the last wide open run until it broke. I don't
think I have had a car run with as clean of a set of plugs
as what came out of the car. I'll post some pics and you
can let me know if they are spot on or not!