Float Level
The Rochester 2 barrel carburetor can have 1 of 2 types of floats, Nitrophyl & Brass. The Nitrophyl is not plastic and is actually solid. The Nitrophyl can only be weighed in grams. We are moving away from Nitrophyl because we have noticed the new manufactures floats are not holding up to ethanol.
If you notice black flakes in the float bowl, then the Nitrophyl might be the problem.
Pump Rod Adjustment
The pump adjustment is important because too much pump travel, or not enough pump travel will cause some hesitation or bog, possible hard starting and not enough fuel being pumped.
- Back out idle speed screw
- Completely close throttle valves in bore
- Measure from top of air horn ring to top of pump rod with adjustable t-scale
- Bend the pump rod at lower angle to obtain specified dimension
Choke Ajustments
- Hold choke valve completely open
- With the thermostatic coil rod disconnected from the upper lever, push downward on rod to end of travel
- With the rod in the fully downward position, the top of rod should cover 1/2 diameter of hole as shown in above image
- To adjust, bend rod at angle where shown
- Turn idle stop screw in until it just contacts the bottom step of the fast idle cam.
- Then turn screw in one more full turn
- Place the idle screw on second step of the fast idle cam against should of high step
- With idle screw in this position, hold the choke valve towards closed position with a rubber band and check the clearance between the upper edge of choke valve and inside air horn wall
- Adjust to specified dimension by bending tang on upper choke lever
Vacuum Break Adjustment
- Push the vacuum break disphragm plunger in until seated (use an outside vacuum source to hold plunger seated if available)
- Start engine or install a vacuum source
- Hold the choke valve towards closed position with a rubber band
- Bend vacuum break link, as shown, so that the specified gauge will fit between the upper edge of the choke valve and inside of air horn
Unloader Adjustment
- Position the throttle valves held wide open
- Hold the choke valve towards the closed position with a rubber band
- Bend the unloader tang on the throttle lever to obtain specified clearance between the upper edge of choke valve and inside air horn wall
